diff --git a/conda/bcolz/meta.yaml b/conda/bcolz/meta.yaml
index 7b785622..5e81384d 100644
--- a/conda/bcolz/meta.yaml
+++ b/conda/bcolz/meta.yaml
@@ -29,9 +29,9 @@ source:
 requirements:
   build:
     - python
-    - setuptools
+    - setuptools >18.0
     - numpy x.x
-    - setuptools_scm
+    - setuptools_scm >1.5.4
     - cython ==0.22.1
 
   run:
@@ -42,7 +42,7 @@ test:
   # Python imports
   imports:
     - bcolz
-#    - bcolz.tests
+    - bcolz.tests
 
   # commands:
     # You can put test commands to be run here.  Use this to test that the
@@ -52,9 +52,9 @@ test:
   # You can also put a file called run_test.py in the recipe that will be run
   # at test time.
 
-#  requires:
-#    - mock
-#    - unittest2 ; python_version < 2.7
+  requires:
+    - mock
+    - unittest2 # [py26]
     # Put any additional test requirements here.  For example
     # - nose
 
diff --git a/etc/requirements.txt b/etc/requirements.txt
index a90571c8..7ffa9527 100644
--- a/etc/requirements.txt
+++ b/etc/requirements.txt
@@ -33,9 +33,6 @@ cyordereddict==0.2.2
 # faster array ops.
 bottleneck==1.0.0
 
-# lru_cache
-functools32==3.2.3.post2;python_version<'3.0'
-
 contextlib2==0.4.0
 
 # networkx requires decorator
diff --git a/setup.py b/setup.py
index edddf402..c7e5594d 100644
--- a/setup.py
+++ b/setup.py
@@ -140,8 +140,9 @@ def _filter_requirements(lines_iter, filter_names=None,
         yield line
 
 
-# We don't currently have any known upper bounds.
-REQ_UPPER_BOUNDS = {}
+REQ_UPPER_BOUNDS = {
+    'bcolz': '<1'
+}
 
 
 def _with_bounds(req):
diff --git a/tests/test_algorithm.py b/tests/test_algorithm.py
index 700818d0..bc89e5f9 100644
--- a/tests/test_algorithm.py
+++ b/tests/test_algorithm.py
@@ -1081,10 +1081,10 @@ class TestBeforeTradingStart(TestCase):
             cls.trading_days[-1], 2, 50
         )
 
-        cls.minute_reader = BcolzMinuteBarReader(cls.tempdir.path)
-        cls.adj_reader = cls.create_adjustments_reader()
+        minute_reader = BcolzMinuteBarReader(cls.tempdir.path)
+        adj_reader = cls.create_adjustments_reader()
 
-        cls.daily_path = cls.tempdir.getpath("testdaily.bcolz")
+        daily_path = cls.tempdir.getpath("testdaily.bcolz")
         dfs = {
             1: create_daily_df_for_asset(cls.env, cls.trading_days[0],
                                          cls.trading_days[-1]),
@@ -1094,7 +1094,7 @@ class TestBeforeTradingStart(TestCase):
                                          cls.trading_days[-1])
         }
         daily_writer = DailyBarWriterFromDataFrames(dfs)
-        daily_writer.write(cls.daily_path, cls.trading_days, dfs)
+        daily_writer.write(daily_path, cls.trading_days, dfs)
 
         cls.sim_params = SimulationParameters(
             period_start=cls.trading_days[1],
@@ -1105,9 +1105,9 @@ class TestBeforeTradingStart(TestCase):
 
         cls.data_portal = DataPortal(
             env=cls.env,
-            equity_daily_reader=BcolzDailyBarReader(cls.daily_path),
-            equity_minute_reader=cls.minute_reader,
-            adjustment_reader=cls.adj_reader
+            equity_daily_reader=BcolzDailyBarReader(daily_path),
+            equity_minute_reader=minute_reader,
+            adjustment_reader=adj_reader
         )
 
     @classmethod
@@ -1131,15 +1131,15 @@ class TestBeforeTradingStart(TestCase):
         # Mergers and Dividends are not tested, but we need to have these
         # anyway
         mergers = pd.DataFrame({}, columns=['effective_date', 'ratio', 'sid'])
-        mergers.effective_date = mergers.effective_date.astype(int)
-        mergers.ratio = mergers.ratio.astype(float)
-        mergers.sid = mergers.sid.astype(int)
+        mergers.effective_date = mergers.effective_date.astype(np.int64)
+        mergers.ratio = mergers.ratio.astype(np.float64)
+        mergers.sid = mergers.sid.astype(np.int64)
 
         dividends = pd.DataFrame({}, columns=['ex_date', 'record_date',
                                               'declared_date', 'pay_date',
                                               'amount', 'sid'])
-        dividends.amount = dividends.amount.astype(float)
-        dividends.sid = dividends.sid.astype(int)
+        dividends.amount = dividends.amount.astype(np.float64)
+        dividends.sid = dividends.sid.astype(np.int64)
 
         adj_writer.write(splits, mergers, dividends)
 
@@ -1147,6 +1147,8 @@ class TestBeforeTradingStart(TestCase):
 
     @classmethod
     def tearDownClass(cls):
+        del cls.data_portal
+        del cls.env
         cls.tempdir.cleanup()
 
     def test_data_in_bts_minute(self):
@@ -1478,6 +1480,7 @@ class TestAlgoScript(TestCase):
 
     @classmethod
     def tearDownClass(cls):
+        del cls.data_portal
         del cls.env
         cls.tempdir.cleanup()
         teardown_logger(cls)
@@ -1867,6 +1870,7 @@ class TestGetDatetime(TestCase):
 
     @classmethod
     def tearDownClass(cls):
+        del cls.data_portal
         del cls.env
         teardown_logger(cls)
         cls.tempdir.cleanup()
@@ -1946,6 +1950,7 @@ class TestTradingControls(TestCase):
 
     @classmethod
     def tearDownClass(cls):
+        del cls.data_portal
         del cls.env
         cls.tempdir.cleanup()
 
@@ -2362,6 +2367,7 @@ class TestAccountControls(TestCase):
 
     @classmethod
     def tearDownClass(cls):
+        del cls.data_portal
         del cls.env
         cls.tempdir.cleanup()
 
@@ -2529,6 +2535,7 @@ class TestFutureFlip(TestCase):
 
     @classmethod
     def tearDownClass(cls):
+        del cls.data_portal
         cls.tempdir.cleanup()
 
     @skip
@@ -2648,6 +2655,7 @@ class TestOrderCancelation(TestCase):
 
     @classmethod
     def tearDownClass(cls):
+        del cls.data_portal
         cls.tempdir.cleanup()
 
     @classmethod
diff --git a/tests/test_api_shim.py b/tests/test_api_shim.py
index d33c3e23..b04fb09d 100644
--- a/tests/test_api_shim.py
+++ b/tests/test_api_shim.py
@@ -164,6 +164,11 @@ class TestAPIShim(TestCase):
             env=cls.env
         )
 
+    @classmethod
+    def tearDownClass(cls):
+        del cls.adj_reader
+        cls.tempdir.cleanup()
+
     @classmethod
     def build_daily_data(cls):
         path = cls.tempdir.getpath("testdaily.bcolz")
@@ -203,24 +208,20 @@ class TestAPIShim(TestCase):
         # Mergers and Dividends are not tested, but we need to have these
         # anyway
         mergers = pd.DataFrame({}, columns=['effective_date', 'ratio', 'sid'])
-        mergers.effective_date = mergers.effective_date.astype(int)
-        mergers.ratio = mergers.ratio.astype(float)
-        mergers.sid = mergers.sid.astype(int)
+        mergers.effective_date = mergers.effective_date.astype(np.int64)
+        mergers.ratio = mergers.ratio.astype(np.float64)
+        mergers.sid = mergers.sid.astype(np.int64)
 
         dividends = pd.DataFrame({}, columns=['ex_date', 'record_date',
                                               'declared_date', 'pay_date',
                                               'amount', 'sid'])
-        dividends.amount = dividends.amount.astype(float)
-        dividends.sid = dividends.sid.astype(int)
+        dividends.amount = dividends.amount.astype(np.float64)
+        dividends.sid = dividends.sid.astype(np.int64)
 
         adj_writer.write(splits, mergers, dividends)
 
         return SQLiteAdjustmentReader(path)
 
-    @classmethod
-    def tearDownClass(cls):
-        cls.tempdir.cleanup()
-
     def setUp(self):
         self.data_portal = DataPortal(
             self.env,
@@ -229,6 +230,9 @@ class TestAPIShim(TestCase):
             adjustment_reader=self.adj_reader
         )
 
+    def tearDown(self):
+        del self.data_portal
+
     @classmethod
     def create_algo(cls, code, filename=None, sim_params=None):
         if sim_params is None:
diff --git a/tests/test_bar_data.py b/tests/test_bar_data.py
index bec4d34b..08ae9fdb 100644
--- a/tests/test_bar_data.py
+++ b/tests/test_bar_data.py
@@ -131,6 +131,8 @@ class TestMinuteBarData(TestBarDataBase):
 
     @classmethod
     def tearDownClass(cls):
+        del cls.data_portal
+        del cls.adjustments_reader
         cls.tempdir.cleanup()
 
     @classmethod
@@ -564,6 +566,8 @@ class TestDailyBarData(TestBarDataBase):
 
     @classmethod
     def tearDownClass(cls):
+        del cls.data_portal
+        del cls.adjustments_reader
         cls.tempdir.cleanup()
 
     @classmethod
diff --git a/tests/test_benchmark.py b/tests/test_benchmark.py
index a0f6757b..2b2960f4 100644
--- a/tests/test_benchmark.py
+++ b/tests/test_benchmark.py
@@ -100,6 +100,7 @@ class TestBenchmark(TestCase):
 
     @classmethod
     def tearDownClass(cls):
+        del cls.data_portal
         del cls.env
         cls.tempdir.cleanup()
 
diff --git a/tests/test_finance.py b/tests/test_finance.py
index 142272a7..5ba73a96 100644
--- a/tests/test_finance.py
+++ b/tests/test_finance.py
@@ -286,7 +286,7 @@ class FinanceTestCase(TestCase):
             else:
                 alternator = 1
 
-            tracker = PerformanceTracker(sim_params, self.env, data_portal)
+            tracker = PerformanceTracker(sim_params, self.env)
 
             # replicate what tradesim does by going through every minute or day
             # of the simulation and processing open orders each time
diff --git a/tests/test_history.py b/tests/test_history.py
index b205e34a..bb59ee03 100644
--- a/tests/test_history.py
+++ b/tests/test_history.py
@@ -108,11 +108,18 @@ class HistoryTestCaseBase(TestCase):
 
         cls.create_data()
 
+    @classmethod
+    def tearDownClass(cls):
+        del cls.adj_reader
+        cls.tempdir.cleanup()
+
     def setUp(self):
         self.create_data_portal()
 
-    @classmethod
-    def create_data_portal(cls):
+    def tearDown(self):
+        del self.data_portal
+
+    def create_data_portal(self):
         raise NotImplementedError()
 
     @classmethod
@@ -169,10 +176,6 @@ class HistoryTestCaseBase(TestCase):
             }
         })
 
-    @classmethod
-    def tearDownClass(cls):
-        cls.tempdir.cleanup()
-
     @classmethod
     def create_adjustments_reader(cls):
         path = cls.tempdir.getpath("test_adjustments.db")
@@ -470,12 +473,11 @@ MINUTE_FIELD_INFO = {
 
 
 class MinuteEquityHistoryTestCase(HistoryTestCaseBase):
-    @classmethod
-    def create_data_portal(cls):
-        cls.data_portal = DataPortal(
-            cls.env,
-            equity_minute_reader=BcolzMinuteBarReader(cls.tempdir.path),
-            adjustment_reader=cls.adj_reader
+    def create_data_portal(self):
+        self.data_portal = DataPortal(
+            self.env,
+            equity_minute_reader=BcolzMinuteBarReader(self.tempdir.path),
+            adjustment_reader=self.adj_reader
         )
 
     @classmethod
@@ -1016,15 +1018,14 @@ class MinuteEquityHistoryTestCase(HistoryTestCaseBase):
 
 
 class DailyEquityHistoryTestCase(HistoryTestCaseBase):
-    @classmethod
-    def create_data_portal(cls):
-        daily_path = cls.tempdir.getpath("testdaily.bcolz")
+    def create_data_portal(self):
+        daily_path = self.tempdir.getpath("testdaily.bcolz")
 
-        cls.data_portal = DataPortal(
-            cls.env,
+        self.data_portal = DataPortal(
+            self.env,
             equity_daily_reader=BcolzDailyBarReader(daily_path),
-            equity_minute_reader=BcolzMinuteBarReader(cls.tempdir.path),
-            adjustment_reader=cls.adj_reader
+            equity_minute_reader=BcolzMinuteBarReader(self.tempdir.path),
+            adjustment_reader=self.adj_reader
         )
 
     @classmethod
diff --git a/tests/test_memoize.py b/tests/test_memoize.py
index 75996e05..c1621249 100644
--- a/tests/test_memoize.py
+++ b/tests/test_memoize.py
@@ -1,6 +1,8 @@
 """
 Tests for zipline.utils.memoize.
 """
+from collections import defaultdict
+import gc
 from unittest import TestCase
 
 from zipline.utils.memoize import remember_last
@@ -32,3 +34,63 @@ class TestRememberLast(TestCase):
         # Calling the old value should still increment the counter.
         self.assertEqual((func(1), call_count[0]), (1, 3))
         self.assertEqual((func(1), call_count[0]), (1, 3))
+
+    def test_remember_last_method(self):
+        call_count = defaultdict(int)
+
+        class clz(object):
+            @remember_last
+            def func(self, x):
+                call_count[(self, x)] += 1
+                return x
+
+        inst1 = clz()
+        self.assertEqual((inst1.func(1), call_count), (1, {(inst1, 1): 1}))
+
+        # Calling again with the same argument should just re-use the old
+        # value, which means func shouldn't get called again.
+        self.assertEqual((inst1.func(1), call_count), (1, {(inst1, 1): 1}))
+
+        # Calling with a new value should increment the counter.
+        self.assertEqual((inst1.func(2), call_count), (2, {(inst1, 1): 1,
+                                                           (inst1, 2): 1}))
+        self.assertEqual((inst1.func(2), call_count), (2, {(inst1, 1): 1,
+                                                           (inst1, 2): 1}))
+
+        # Calling the old value should still increment the counter.
+        self.assertEqual((inst1.func(1), call_count), (1, {(inst1, 1): 2,
+                                                           (inst1, 2): 1}))
+        self.assertEqual((inst1.func(1), call_count), (1, {(inst1, 1): 2,
+                                                           (inst1, 2): 1}))
+
+        inst2 = clz()
+        self.assertEqual((inst2.func(1), call_count),
+                         (1, {(inst1, 1): 2, (inst1, 2): 1,
+                              (inst2, 1): 1}))
+        self.assertEqual((inst2.func(1), call_count),
+                         (1, {(inst1, 1): 2, (inst1, 2): 1,
+                              (inst2, 1): 1}))
+
+        self.assertEqual((inst2.func(2), call_count),
+                         (2, {(inst1, 1): 2, (inst1, 2): 1,
+                              (inst2, 1): 1, (inst2, 2): 1}))
+        self.assertEqual((inst2.func(2), call_count),
+                         (2, {(inst1, 1): 2, (inst1, 2): 1,
+                              (inst2, 1): 1, (inst2, 2): 1}))
+
+        self.assertEqual((inst2.func(1), call_count),
+                         (1, {(inst1, 1): 2, (inst1, 2): 1,
+                              (inst2, 1): 2, (inst2, 2): 1}))
+        self.assertEqual((inst2.func(1), call_count),
+                         (1, {(inst1, 1): 2, (inst1, 2): 1,
+                              (inst2, 1): 2, (inst2, 2): 1}))
+
+        # Remove the above references to the instances and ensure that
+        # remember_last has not made its own.
+        del inst1, inst2
+        call_count.clear()
+        while gc.collect():
+            pass
+
+        self.assertFalse([inst for inst in gc.get_objects()
+                          if type(inst) == clz])
diff --git a/tests/test_perf_tracking.py b/tests/test_perf_tracking.py
index 11b3886e..4174ea52 100644
--- a/tests/test_perf_tracking.py
+++ b/tests/test_perf_tracking.py
@@ -50,7 +50,7 @@ from zipline.utils.serialization_utils import (
     loads_with_persistent_ids, dumps_with_persistent_ids
 )
 from zipline.testing.core import create_data_portal_from_trade_history, \
-    create_empty_splits_mergers_frame, FakeDataPortal
+    create_empty_splits_mergers_frame
 
 logger = logging.getLogger('Test Perf Tracking')
 
@@ -167,7 +167,7 @@ def calculate_results(sim_params,
     splits = splits or {}
     commissions = commissions or {}
 
-    perf_tracker = perf.PerformanceTracker(sim_params, env, data_portal)
+    perf_tracker = perf.PerformanceTracker(sim_params, env)
 
     results = []
 
@@ -189,8 +189,10 @@ def calculate_results(sim_params,
         except KeyError:
             pass
 
-        msg = perf_tracker.handle_market_close_daily(date)
-        perf_tracker.position_tracker.sync_last_sale_prices(date, False)
+        msg = perf_tracker.handle_market_close_daily(date, data_portal)
+        perf_tracker.position_tracker.sync_last_sale_prices(
+            date, False, data_portal,
+        )
         msg['account'] = perf_tracker.get_account(True)
         results.append(copy.deepcopy(msg))
     return results
@@ -265,9 +267,7 @@ class TestSplitPerformance(unittest.TestCase):
     def test_multiple_splits(self):
         # if multiple positions all have splits at the same time, verify that
         # the total leftover cash is correct
-        perf_tracker = perf.PerformanceTracker(
-            self.sim_params, self.env, FakeDataPortal()
-        )
+        perf_tracker = perf.PerformanceTracker(self.sim_params, self.env)
 
         asset1 = self.env.asset_finder.retrieve_asset(1)
         asset2 = self.env.asset_finder.retrieve_asset(2)
@@ -1240,11 +1240,10 @@ class TestPositionPerformance(unittest.TestCase):
         txn1 = create_txn(self.asset1, trades_1[0].dt, 10.0, 100)
         txn2 = create_txn(self.asset2, trades_1[0].dt, 10.0, -100)
 
-        pt = perf.PositionTracker(self.env.asset_finder, data_portal,
+        pt = perf.PositionTracker(self.env.asset_finder,
                                   self.sim_params.data_frequency)
         pp = perf.PerformancePeriod(1000.0, self.env.asset_finder,
-                                    self.sim_params.data_frequency,
-                                    data_portal)
+                                    self.sim_params.data_frequency)
         pp.position_tracker = pt
         pt.execute_transaction(txn1)
         pp.handle_execution(txn1)
@@ -1252,7 +1251,7 @@ class TestPositionPerformance(unittest.TestCase):
         pp.handle_execution(txn2)
 
         dt = trades_1[-2].dt
-        pt.sync_last_sale_prices(dt, False)
+        pt.sync_last_sale_prices(dt, False, data_portal)
 
         pp.calculate_performance()
 
@@ -1280,7 +1279,7 @@ class TestPositionPerformance(unittest.TestCase):
                       net_liquidation=1000.0)
 
         dt = trades_1[-1].dt
-        pt.sync_last_sale_prices(dt, False)
+        pt.sync_last_sale_prices(dt, False, data_portal)
 
         pp.calculate_performance()
 
@@ -1333,11 +1332,10 @@ class TestPositionPerformance(unittest.TestCase):
             self.sim_params,
             {1: trades})
         txn = create_txn(self.asset1, trades[1].dt, 10.0, 1000)
-        pt = perf.PositionTracker(self.env.asset_finder, data_portal,
+        pt = perf.PositionTracker(self.env.asset_finder,
                                   self.sim_params.data_frequency)
         pp = perf.PerformancePeriod(1000.0, self.env.asset_finder,
-                                    self.sim_params.data_frequency,
-                                    data_portal)
+                                    self.sim_params.data_frequency)
         pp.position_tracker = pt
 
         pt.execute_transaction(txn)
@@ -1355,7 +1353,7 @@ class TestPositionPerformance(unittest.TestCase):
             shorts_count=0)
 
         # Validate that the account attributes were updated.
-        pt.sync_last_sale_prices(trades[-2].dt, False)
+        pt.sync_last_sale_prices(trades[-2].dt, False, data_portal)
 
         # Validate that the account attributes were updated.
         account = pp.as_account()
@@ -1373,7 +1371,7 @@ class TestPositionPerformance(unittest.TestCase):
                       net_liquidation=1000.0)
 
         # now simulate a price jump to $11
-        pt.sync_last_sale_prices(trades[-1].dt, False)
+        pt.sync_last_sale_prices(trades[-1].dt, False, data_portal)
 
         pp.calculate_performance()
 
@@ -1425,11 +1423,10 @@ class TestPositionPerformance(unittest.TestCase):
             self.sim_params,
             {1: trades})
         txn = create_txn(self.asset1, trades[1].dt, 10.0, 100)
-        pt = perf.PositionTracker(self.env.asset_finder, data_portal,
+        pt = perf.PositionTracker(self.env.asset_finder,
                                   self.sim_params.data_frequency)
         pp = perf.PerformancePeriod(1000.0, self.env.asset_finder,
                                     self.sim_params.data_frequency,
-                                    data_portal,
                                     period_open=self.sim_params.period_start,
                                     period_close=self.sim_params.period_end)
         pp.position_tracker = pt
@@ -1444,7 +1441,7 @@ class TestPositionPerformance(unittest.TestCase):
         # stocks with a last sale price of 0.
         self.assertEqual(pp.positions[1].last_sale_price, 10.0)
 
-        pt.sync_last_sale_prices(trades[-1].dt, False)
+        pt.sync_last_sale_prices(trades[-1].dt, False, data_portal)
 
         pp.calculate_performance()
 
@@ -1544,18 +1541,17 @@ single short-sale transaction"""
             {1: trades})
 
         txn = create_txn(self.asset1, trades[1].dt, 10.0, -100)
-        pt = perf.PositionTracker(self.env.asset_finder, data_portal,
+        pt = perf.PositionTracker(self.env.asset_finder,
                                   self.sim_params.data_frequency)
         pp = perf.PerformancePeriod(
             1000.0, self.env.asset_finder,
-            self.sim_params.data_frequency,
-            data_portal)
+            self.sim_params.data_frequency)
         pp.position_tracker = pt
 
         pt.execute_transaction(txn)
         pp.handle_execution(txn)
 
-        pt.sync_last_sale_prices(trades_1[-1].dt, False)
+        pt.sync_last_sale_prices(trades_1[-1].dt, False, data_portal)
 
         pp.calculate_performance()
 
@@ -1611,7 +1607,7 @@ single short-sale transaction"""
         # simulate a rollover to a new period
         pp.rollover()
 
-        pt.sync_last_sale_prices(trades[-1].dt, False)
+        pt.sync_last_sale_prices(trades[-1].dt, False, data_portal)
 
         pp.calculate_performance()
 
@@ -1665,17 +1661,16 @@ single short-sale transaction"""
         )
 
         # now run a performance period encompassing the entire trade sample.
-        ptTotal = perf.PositionTracker(self.env.asset_finder, data_portal,
+        ptTotal = perf.PositionTracker(self.env.asset_finder,
                                        self.sim_params.data_frequency)
         ppTotal = perf.PerformancePeriod(1000.0, self.env.asset_finder,
-                                         self.sim_params.data_frequency,
-                                         data_portal)
+                                         self.sim_params.data_frequency)
         ppTotal.position_tracker = pt
 
         ptTotal.execute_transaction(txn)
         ppTotal.handle_execution(txn)
 
-        ptTotal.sync_last_sale_prices(trades[-1].dt, False)
+        ptTotal.sync_last_sale_prices(trades[-1].dt, False, data_portal)
 
         ppTotal.calculate_performance()
 
@@ -1778,11 +1773,10 @@ cost of sole txn in test"
         )
 
         txn = create_txn(self.asset3, trades[1].dt, 10.0, 1)
-        pt = perf.PositionTracker(self.env.asset_finder, data_portal,
+        pt = perf.PositionTracker(self.env.asset_finder,
                                   self.sim_params.data_frequency)
         pp = perf.PerformancePeriod(1000.0, self.env.asset_finder,
-                                    self.sim_params.data_frequency,
-                                    data_portal)
+                                    self.sim_params.data_frequency)
         pp.position_tracker = pt
 
         pt.execute_transaction(txn)
@@ -1795,7 +1789,7 @@ cost of sole txn in test"
         # stocks with a last sale price of 0.
         self.assertEqual(pp.positions[3].last_sale_price, 10.0)
 
-        pt.sync_last_sale_prices(trades[-1].dt, False)
+        pt.sync_last_sale_prices(trades[-1].dt, False, data_portal)
         pp.calculate_performance()
 
         self.assertEqual(
@@ -1899,17 +1893,16 @@ single short-sale transaction"""
         trades_1 = trades[:-2]
 
         txn = create_txn(self.asset3, trades[0].dt, 10.0, -1)
-        pt = perf.PositionTracker(self.env.asset_finder, data_portal,
+        pt = perf.PositionTracker(self.env.asset_finder,
                                   self.sim_params.data_frequency)
         pp = perf.PerformancePeriod(1000.0, self.env.asset_finder,
-                                    self.sim_params.data_frequency,
-                                    data_portal)
+                                    self.sim_params.data_frequency)
         pp.position_tracker = pt
 
         pt.execute_transaction(txn)
         pp.handle_execution(txn)
 
-        pt.sync_last_sale_prices(trades[-3].dt, False)
+        pt.sync_last_sale_prices(trades[-3].dt, False, data_portal)
         pp.calculate_performance()
 
         self.assertEqual(
@@ -1969,7 +1962,7 @@ single short-sale transaction"""
         # simulate a rollover to a new period
         pp.rollover()
 
-        pt.sync_last_sale_prices(trades_2[-1].dt, False)
+        pt.sync_last_sale_prices(trades_2[-1].dt, False, data_portal)
         pp.calculate_performance()
 
         self.assertEqual(
@@ -2027,21 +2020,20 @@ single short-sale transaction"""
         )
 
         # now run a performance period encompassing the entire trade sample.
-        ptTotal = perf.PositionTracker(self.env.asset_finder, data_portal,
+        ptTotal = perf.PositionTracker(self.env.asset_finder,
                                        self.sim_params.data_frequency)
         ppTotal = perf.PerformancePeriod(1000.0, self.env.asset_finder,
-                                         self.sim_params.data_frequency,
-                                         data_portal)
+                                         self.sim_params.data_frequency)
         ppTotal.position_tracker = ptTotal
 
         for trade in trades_1:
-            ptTotal.sync_last_sale_prices(trade.dt, False)
+            ptTotal.sync_last_sale_prices(trade.dt, False, data_portal)
 
         ptTotal.execute_transaction(txn)
         ppTotal.handle_execution(txn)
 
         for trade in trades_2:
-            ptTotal.sync_last_sale_prices(trade.dt, False)
+            ptTotal.sync_last_sale_prices(trade.dt, False, data_portal)
 
         ppTotal.calculate_performance()
 
@@ -2144,11 +2136,10 @@ trade after cover"""
 
         short_txn = create_txn(self.asset1, trades[1].dt, 10.0, -100)
         cover_txn = create_txn(self.asset1, trades[6].dt, 7.0, 100)
-        pt = perf.PositionTracker(self.env.asset_finder, data_portal,
+        pt = perf.PositionTracker(self.env.asset_finder,
                                   self.sim_params.data_frequency)
         pp = perf.PerformancePeriod(1000.0, self.env.asset_finder,
-                                    self.sim_params.data_frequency,
-                                    data_portal)
+                                    self.sim_params.data_frequency)
         pp.position_tracker = pt
 
         pt.execute_transaction(short_txn)
@@ -2156,7 +2147,7 @@ trade after cover"""
         pt.execute_transaction(cover_txn)
         pp.handle_execution(cover_txn)
 
-        pt.sync_last_sale_prices(trades[-1].dt, False)
+        pt.sync_last_sale_prices(trades[-1].dt, False, data_portal)
 
         pp.calculate_performance()
 
@@ -2231,13 +2222,12 @@ shares in position"
             self.sim_params,
             {1: trades})
 
-        pt = perf.PositionTracker(self.env.asset_finder, data_portal,
+        pt = perf.PositionTracker(self.env.asset_finder,
                                   self.sim_params.data_frequency)
         pp = perf.PerformancePeriod(
             1000.0,
             self.env.asset_finder,
             self.sim_params.data_frequency,
-            data_portal,
             period_open=self.sim_params.period_start,
             period_close=self.sim_params.trading_days[-1]
         )
@@ -2264,7 +2254,7 @@ shares in position"
             "should have a cost basis of 11"
         )
 
-        pt.sync_last_sale_prices(dt, False)
+        pt.sync_last_sale_prices(dt, False, data_portal)
 
         pp.calculate_performance()
 
@@ -2281,7 +2271,7 @@ shares in position"
         pp.handle_execution(sale_txn)
 
         dt = down_tick.dt
-        pt.sync_last_sale_prices(dt, False)
+        pt.sync_last_sale_prices(dt, False, data_portal)
 
         pp.calculate_performance()
         self.assertEqual(
@@ -2299,11 +2289,10 @@ shares in position"
 
         self.assertEqual(pp.pnl, -800, "this period goes from +400 to -400")
 
-        pt3 = perf.PositionTracker(self.env.asset_finder, data_portal,
+        pt3 = perf.PositionTracker(self.env.asset_finder,
                                    self.sim_params.data_frequency)
         pp3 = perf.PerformancePeriod(1000.0, self.env.asset_finder,
-                                     self.sim_params.data_frequency,
-                                     data_portal)
+                                     self.sim_params.data_frequency)
         pp3.position_tracker = pt3
 
         average_cost = 0
@@ -2317,7 +2306,7 @@ shares in position"
         pp3.handle_execution(sale_txn)
 
         trades.append(down_tick)
-        pt3.sync_last_sale_prices(trades[-1].dt, False)
+        pt3.sync_last_sale_prices(trades[-1].dt, False, data_portal)
 
         pp3.calculate_performance()
         self.assertEqual(
@@ -2351,18 +2340,11 @@ shares in position"
         )
         cost_bases = [10, 10, 0, 8, 9, 9, 13, 13.5]
 
-        trades = factory.create_trade_history(*history_args)
         transactions = factory.create_txn_history(*history_args)
 
-        data_portal = create_data_portal_from_trade_history(
-            self.env,
-            self.tempdir,
-            self.sim_params,
-            {1: trades})
-
-        pt = perf.PositionTracker(self.env.asset_finder, data_portal,
+        pt = perf.PositionTracker(self.env.asset_finder,
                                   self.sim_params.data_frequency)
-        pp = perf.PerformancePeriod(1000.0, self.env.asset_finder, data_portal,
+        pp = perf.PerformancePeriod(1000.0, self.env.asset_finder,
                                     self.sim_params.data_frequency)
         pp.position_tracker = pt
 
@@ -2413,22 +2395,8 @@ class TestPositionTracker(unittest.TestCase):
         sim_params = factory.create_simulation_parameters(
             num_days=4, env=self.env
         )
-        trades = factory.create_trade_history(
-            1,
-            [10, 10, 10, 11],
-            [100, 100, 100, 100],
-            oneday,
-            sim_params,
-            env=self.env
-        )
 
-        data_portal = create_data_portal_from_trade_history(
-            self.env,
-            self.tempdir,
-            sim_params,
-            {1: trades})
-
-        pt = perf.PositionTracker(self.env.asset_finder, data_portal,
+        pt = perf.PositionTracker(self.env.asset_finder,
                                   sim_params.data_frequency)
         pos_stats = pt.stats()
 
@@ -2450,7 +2418,7 @@ class TestPositionTracker(unittest.TestCase):
             self.assertNotIsInstance(val, (bool, np.bool_))
 
     def test_position_values_and_exposures(self):
-        pt = perf.PositionTracker(self.env.asset_finder, None, None)
+        pt = perf.PositionTracker(self.env.asset_finder, None)
         dt = pd.Timestamp("1984/03/06 3:00PM")
         pos1 = perf.Position(1, amount=np.float64(10.0),
                              last_sale_date=dt, last_sale_price=10)
@@ -2482,7 +2450,7 @@ class TestPositionTracker(unittest.TestCase):
         self.assertEqual(100 - 200 + 300000 - 400000, pos_stats.net_exposure)
 
     def test_update_positions(self):
-        pt = perf.PositionTracker(self.env.asset_finder, None, None)
+        pt = perf.PositionTracker(self.env.asset_finder, None)
         dt = pd.Timestamp("2014/01/01 3:00PM")
         pos1 = perf.Position(1, amount=np.float64(10.0),
                              last_sale_date=dt, last_sale_price=10)
diff --git a/tests/utils/daily_bar_writer.py b/tests/utils/daily_bar_writer.py
index 344e664f..df69c55c 100644
--- a/tests/utils/daily_bar_writer.py
+++ b/tests/utils/daily_bar_writer.py
@@ -1,6 +1,7 @@
 from numpy import (
     float64,
-    uint32
+    uint32,
+    int64,
 )
 from bcolz import ctable
 
@@ -37,8 +38,9 @@ class DailyBarWriterFromDataFrames(BcolzDailyBarWriter):
             return array.astype(uint32)
         elif colname == 'day':
             nanos_per_second = (1000 * 1000 * 1000)
-            self.check_uint_safe(arrmax.view(int) / nanos_per_second, colname)
-            return (array.view(int) / nanos_per_second).astype(uint32)
+            self.check_uint_safe(arrmax.view(int64) / nanos_per_second,
+                                 colname)
+            return (array.view(int64) / nanos_per_second).astype(uint32)
 
     @staticmethod
     def check_uint_safe(value, colname):
diff --git a/zipline/algorithm.py b/zipline/algorithm.py
index 8e204710..98f75b50 100644
--- a/zipline/algorithm.py
+++ b/zipline/algorithm.py
@@ -492,7 +492,6 @@ class TradingAlgorithm(object):
             self.perf_tracker = PerformanceTracker(
                 sim_params=self.sim_params,
                 env=self.trading_environment,
-                data_portal=self.data_portal
             )
 
             # Set the dt initially to the period start by forcing it to change.
@@ -603,14 +602,17 @@ class TradingAlgorithm(object):
 
         # Create zipline and loop through simulated_trading.
         # Each iteration returns a perf dictionary
-        perfs = []
-        for perf in self.get_generator():
-            perfs.append(perf)
+        try:
+            perfs = []
+            for perf in self.get_generator():
+                perfs.append(perf)
 
-        # convert perf dict to pandas dataframe
-        daily_stats = self._create_daily_stats(perfs)
+            # convert perf dict to pandas dataframe
+            daily_stats = self._create_daily_stats(perfs)
 
-        self.analyze(daily_stats)
+            self.analyze(daily_stats)
+        finally:
+            self.data_portal = None
 
         return daily_stats
 
@@ -1057,7 +1059,7 @@ class TradingAlgorithm(object):
     def updated_portfolio(self):
         if self.portfolio_needs_update:
             self.perf_tracker.position_tracker.sync_last_sale_prices(
-                self.datetime, self._in_before_trading_start)
+                self.datetime, self._in_before_trading_start, self.data_portal)
             self._portfolio = \
                 self.perf_tracker.get_portfolio(self.performance_needs_update)
             self.portfolio_needs_update = False
@@ -1071,7 +1073,7 @@ class TradingAlgorithm(object):
     def updated_account(self):
         if self.account_needs_update:
             self.perf_tracker.position_tracker.sync_last_sale_prices(
-                self.datetime, self._in_before_trading_start)
+                self.datetime, self._in_before_trading_start, self.data_portal)
             self._account = \
                 self.perf_tracker.get_account(self.performance_needs_update)
             self.account_needs_update = False
diff --git a/zipline/data/data_portal.py b/zipline/data/data_portal.py
index 9db60e5c..f8598c38 100644
--- a/zipline/data/data_portal.py
+++ b/zipline/data/data_portal.py
@@ -31,13 +31,12 @@ from zipline.data.us_equity_loader import (
 )
 
 from zipline.utils import tradingcalendar
-from zipline.utils.compat import lru_cache
 from zipline.utils.math_utils import (
     nansum,
     nanmean,
     nanstd
 )
-from zipline.utils.memoize import remember_last
+from zipline.utils.memoize import remember_last, weak_lru_cache
 from zipline.errors import (
     NoTradeDataAvailableTooEarly,
     NoTradeDataAvailableTooLate,
@@ -1091,10 +1090,6 @@ class DataPortal(object):
 
         return data
 
-    @remember_last
-    def _get_market_minutes_for_day(self, end_date):
-        return self.env.market_minutes_for_day(pd.Timestamp(end_date))
-
     def _get_history_daily_window_equities(
             self, assets, days_for_window, end_dt, field_to_use):
         ends_at_midnight = end_dt.hour == 0 and end_dt.minute == 0
@@ -1686,7 +1681,7 @@ class DataPortal(object):
         else:
             return [assets] if isinstance(assets, Asset) else []
 
-    @lru_cache(20)
+    @weak_lru_cache(20)
     def _get_minute_count_for_transform(self, ending_minute, days_count):
         # cache size picked somewhat loosely.  this code exists purely to
         # handle deprecated API.
diff --git a/zipline/data/minute_bars.py b/zipline/data/minute_bars.py
index fbee5f4c..09c9d994 100644
--- a/zipline/data/minute_bars.py
+++ b/zipline/data/minute_bars.py
@@ -163,10 +163,10 @@ class BcolzMinuteBarMetadata(object):
             'first_trading_day': str(self.first_trading_day.date()),
             'market_opens': self.market_opens.values.
             astype('datetime64[m]').
-            astype(int).tolist(),
+            astype(np.int64).tolist(),
             'market_closes': self.market_closes.values.
             astype('datetime64[m]').
-            astype(int).tolist(),
+            astype(np.int64).tolist(),
             'ohlc_ratio': self.ohlc_ratio,
         }
         with open(self.metadata_path(rootdir), 'w+') as fp:
@@ -603,10 +603,10 @@ class BcolzMinuteBarReader(object):
 
         self._market_opens = metadata.market_opens
         self._market_open_values = metadata.market_opens.values.\
-            astype('datetime64[m]').astype(int)
+            astype('datetime64[m]').astype(np.int64)
         self._market_closes = metadata.market_closes
         self._market_close_values = metadata.market_closes.values.\
-            astype('datetime64[m]').astype(int)
+            astype('datetime64[m]').astype(np.int64)
 
         self._ohlc_inverse = 1.0 / metadata.ohlc_ratio
 
@@ -643,7 +643,7 @@ class BcolzMinuteBarReader(object):
         """
         market_opens = self._market_opens.values.astype('datetime64[m]')
         market_closes = self._market_closes.values.astype('datetime64[m]')
-        minutes_per_day = (market_closes - market_opens).astype(int)
+        minutes_per_day = (market_closes - market_opens).astype(np.int64)
         early_indices = np.where(
             minutes_per_day != US_EQUITIES_MINUTES_PER_DAY - 1)[0]
         regular_closes = market_opens[early_indices] + timedelta64(
diff --git a/zipline/finance/performance/period.py b/zipline/finance/performance/period.py
index 1488d666..23a1864c 100644
--- a/zipline/finance/performance/period.py
+++ b/zipline/finance/performance/period.py
@@ -133,7 +133,6 @@ class PerformancePeriod(object):
             starting_cash,
             asset_finder,
             data_frequency,
-            data_portal,
             period_open=None,
             period_close=None,
             keep_transactions=True,
@@ -144,8 +143,6 @@ class PerformancePeriod(object):
         self.asset_finder = asset_finder
         self.data_frequency = data_frequency
 
-        self._data_portal = data_portal
-
         self.period_open = period_open
         self.period_close = period_close
 
diff --git a/zipline/finance/performance/position_tracker.py b/zipline/finance/performance/position_tracker.py
index 88d68dc5..ea1600a1 100644
--- a/zipline/finance/performance/position_tracker.py
+++ b/zipline/finance/performance/position_tracker.py
@@ -119,14 +119,9 @@ def calc_gross_value(long_value, short_value):
 
 class PositionTracker(object):
 
-    def __init__(self, asset_finder, data_portal, data_frequency):
+    def __init__(self, asset_finder, data_frequency):
         self.asset_finder = asset_finder
 
-        # FIXME really want to avoid storing a data portal here,
-        # but the path to get to maybe_create_close_position_transaction
-        # is long and tortuous
-        self._data_portal = data_portal
-
         # sid => position object
         self.positions = positiondict()
         # Arrays for quick calculations of positions value
@@ -316,12 +311,12 @@ class PositionTracker(object):
 
         return net_cash_payment
 
-    def maybe_create_close_position_transaction(self, asset, dt):
+    def maybe_create_close_position_transaction(self, asset, dt, data_portal):
         if not self.positions.get(asset):
             return None
 
         amount = self.positions.get(asset).amount
-        price = self._data_portal.get_spot_value(
+        price = data_portal.get_spot_value(
             asset, 'price', dt, self.data_frequency)
 
         # Get the last traded price if price is no longer available
@@ -372,8 +367,8 @@ class PositionTracker(object):
                 positions.append(pos.to_dict())
         return positions
 
-    def sync_last_sale_prices(self, dt, handle_non_market_minutes):
-        data_portal = self._data_portal
+    def sync_last_sale_prices(self, dt, handle_non_market_minutes,
+                              data_portal):
         if not handle_non_market_minutes:
             for asset, position in iteritems(self.positions):
                 last_sale_price = data_portal.get_spot_value(
diff --git a/zipline/finance/performance/tracker.py b/zipline/finance/performance/tracker.py
index 6307416b..ff98ebb1 100644
--- a/zipline/finance/performance/tracker.py
+++ b/zipline/finance/performance/tracker.py
@@ -78,7 +78,7 @@ class PerformanceTracker(object):
     """
     Tracks the performance of the algorithm.
     """
-    def __init__(self, sim_params, env, data_portal):
+    def __init__(self, sim_params, env):
         self.sim_params = sim_params
         self.env = env
 
@@ -101,15 +101,8 @@ class PerformanceTracker(object):
 
         self.trading_days = all_trading_days[mask]
 
-        self._data_portal = data_portal
-        if data_portal is not None:
-            self._adjustment_reader = data_portal._adjustment_reader
-        else:
-            self._adjustment_reader = None
-
         self.position_tracker = PositionTracker(
             asset_finder=env.asset_finder,
-            data_portal=data_portal,
             data_frequency=self.sim_params.data_frequency)
 
         if self.emission_rate == 'daily':
@@ -132,7 +125,6 @@ class PerformanceTracker(object):
             # initial cash is your capital base.
             starting_cash=self.capital_base,
             data_frequency=self.sim_params.data_frequency,
-            data_portal=data_portal,
             # the cumulative period will be calculated over the entire test.
             period_open=self.period_start,
             period_close=self.period_end,
@@ -152,7 +144,6 @@ class PerformanceTracker(object):
             # initial cash is your capital base.
             starting_cash=self.capital_base,
             data_frequency=self.sim_params.data_frequency,
-            data_portal=data_portal,
             # the daily period will be calculated for the market day
             period_open=self.market_open,
             period_close=self.market_close,
@@ -264,13 +255,13 @@ class PerformanceTracker(object):
         self.cumulative_performance.handle_commission(cost)
         self.todays_performance.handle_commission(cost)
 
-    def process_close_position(self, asset, dt):
+    def process_close_position(self, asset, dt, data_portal):
         txn = self.position_tracker.\
-            maybe_create_close_position_transaction(asset, dt)
+            maybe_create_close_position_transaction(asset, dt, data_portal)
         if txn:
             self.process_transaction(txn)
 
-    def check_upcoming_dividends(self, next_trading_day):
+    def check_upcoming_dividends(self, next_trading_day, adjustment_reader):
         """
         Check if we currently own any stocks with dividends whose ex_date is
         the next trading day.  Track how much we should be payed on those
@@ -280,7 +271,7 @@ class PerformanceTracker(object):
         is the next trading day.  Apply all such benefits, then recalculate
         performance.
         """
-        if self._adjustment_reader is None:
+        if adjustment_reader is None:
             return
         position_tracker = self.position_tracker
         held_sids = set(position_tracker.positions)
@@ -291,10 +282,10 @@ class PerformanceTracker(object):
         if held_sids:
             asset_finder = self.env.asset_finder
 
-            cash_dividends = self._adjustment_reader.\
+            cash_dividends = adjustment_reader.\
                 get_dividends_with_ex_date(held_sids, next_trading_day,
                                            asset_finder)
-            stock_dividends = self._adjustment_reader.\
+            stock_dividends = adjustment_reader.\
                 get_stock_dividends_with_ex_date(held_sids, next_trading_day,
                                                  asset_finder)
 
@@ -310,7 +301,7 @@ class PerformanceTracker(object):
         self.cumulative_performance.handle_dividends_paid(net_cash_payment)
         self.todays_performance.handle_dividends_paid(net_cash_payment)
 
-    def handle_minute_close(self, dt):
+    def handle_minute_close(self, dt, data_portal):
         """
         Handles the close of the given minute. This includes handling
         market-close functions if the given minute is the end of the market
@@ -327,7 +318,7 @@ class PerformanceTracker(object):
             A tuple of the minute perf packet and daily perf packet.
             If the market day has not ended, the daily perf packet is None.
         """
-        self.position_tracker.sync_last_sale_prices(dt, False)
+        self.position_tracker.sync_last_sale_prices(dt, False, data_portal)
         self.update_performance()
         todays_date = normalize_date(dt)
         account = self.get_account(False)
@@ -346,16 +337,18 @@ class PerformanceTracker(object):
         # if this is the close, update dividends for the next day.
         # Return the performance tuple
         if dt == self.market_close:
-            return minute_packet, self._handle_market_close(todays_date)
+            return minute_packet, self._handle_market_close(
+                todays_date, data_portal._adjustment_reader,
+            )
         else:
             return minute_packet, None
 
-    def handle_market_close_daily(self, dt):
+    def handle_market_close_daily(self, dt, data_portal):
         """
         Function called after handle_data when running with daily emission
         rate.
         """
-        self.position_tracker.sync_last_sale_prices(dt, False)
+        self.position_tracker.sync_last_sale_prices(dt, False, data_portal)
         self.update_performance()
         completed_date = self.day
         account = self.get_account(False)
@@ -368,11 +361,12 @@ class PerformanceTracker(object):
             benchmark_value,
             account.leverage)
 
-        daily_packet = self._handle_market_close(completed_date)
-
+        daily_packet = self._handle_market_close(
+            completed_date, data_portal._adjustment_reader,
+        )
         return daily_packet
 
-    def _handle_market_close(self, completed_date):
+    def _handle_market_close(self, completed_date, adjustment_reader):
 
         # increment the day counter before we move markers forward.
         self.day_count += 1.0
@@ -406,7 +400,8 @@ class PerformanceTracker(object):
             return daily_update
 
         # Check for any dividends, then return the daily perf packet
-        self.check_upcoming_dividends(next_trading_day=next_trading_day)
+        self.check_upcoming_dividends(next_trading_day=next_trading_day,
+                                      adjustment_reader=adjustment_reader)
         return daily_update
 
     def handle_simulation_end(self):
diff --git a/zipline/gens/tradesimulation.py b/zipline/gens/tradesimulation.py
index b9200a5b..33a9c432 100644
--- a/zipline/gens/tradesimulation.py
+++ b/zipline/gens/tradesimulation.py
@@ -97,20 +97,9 @@ class AlgorithmSimulator(object):
         Main generator work loop.
         """
         algo = self.algo
-        algo.data_portal = self.data_portal
-        handle_data = algo.event_manager.handle_data
-        current_data = self.current_data
 
-        data_portal = self.data_portal
-
-        # can't cache a pointer to algo.perf_tracker because we're not
-        # guaranteed that the algo doesn't swap out perf trackers during
-        # its lifetime.
-        # likewise, we can't cache a pointer to the blotter.
-
-        algo.perf_tracker.position_tracker.data_portal = data_portal
-
-        def every_bar(dt_to_use):
+        def every_bar(dt_to_use, current_data=self.current_data,
+                      handle_data=algo.event_manager.handle_data):
             # called every tick (minute or day).
 
             self.simulation_dt = dt_to_use
@@ -152,7 +141,8 @@ class AlgorithmSimulator(object):
             self.algo.account_needs_update = True
             self.algo.performance_needs_update = True
 
-        def once_a_day(midnight_dt):
+        def once_a_day(midnight_dt, current_data=self.current_data,
+                       data_portal=self.data_portal):
             # Get the positions before updating the date so that prices are
             # fetched for trading close instead of midnight
             positions = algo.perf_tracker.position_tracker.positions
@@ -183,11 +173,15 @@ class AlgorithmSimulator(object):
             # call before trading start
             algo.before_trading_start(current_data)
 
-        def handle_benchmark(date):
+        def handle_benchmark(date, benchmark_source=self.benchmark_source):
             algo.perf_tracker.all_benchmark_returns[date] = \
-                self.benchmark_source.get_value(date)
+                benchmark_source.get_value(date)
+
+        def on_exit():
+            self.benchmark_source = self.current_data = self.data_portal = None
 
         with ExitStack() as stack:
+            stack.callback(on_exit)
             stack.enter_context(self.processor)
             stack.enter_context(ZiplineAPI(self.algo))
 
@@ -245,8 +239,9 @@ class AlgorithmSimulator(object):
         assets_to_clear = \
             [asset for asset in position_assets if past_auto_close_date(asset)]
         perf_tracker = algo.perf_tracker
+        data_portal = self.data_portal
         for asset in assets_to_clear:
-            perf_tracker.process_close_position(asset, dt)
+            perf_tracker.process_close_position(asset, dt, data_portal)
 
         # Remove open orders for any sids that have reached their
         # auto_close_date.
@@ -257,23 +252,25 @@ class AlgorithmSimulator(object):
         for asset in assets_to_cancel:
             blotter.cancel_all_orders_for_asset(asset)
 
-    @staticmethod
-    def _get_daily_message(dt, algo, perf_tracker):
+    def _get_daily_message(self, dt, algo, perf_tracker):
         """
         Get a perf message for the given datetime.
         """
-        perf_message = perf_tracker.handle_market_close_daily(dt)
+        perf_message = perf_tracker.handle_market_close_daily(
+            dt, self.data_portal,
+        )
         perf_message['daily_perf']['recorded_vars'] = algo.recorded_vars
         return perf_message
 
-    @staticmethod
-    def _get_minute_message(dt, algo, perf_tracker):
+    def _get_minute_message(self, dt, algo, perf_tracker):
         """
         Get a perf message for the given datetime.
         """
         rvars = algo.recorded_vars
 
-        minute_message, daily_message = perf_tracker.handle_minute_close(dt)
+        minute_message, daily_message = perf_tracker.handle_minute_close(
+            dt, self.data_portal,
+        )
         minute_message['minute_perf']['recorded_vars'] = rvars
 
         if daily_message:
diff --git a/zipline/protocol.py b/zipline/protocol.py
index da0d2397..9db94914 100644
--- a/zipline/protocol.py
+++ b/zipline/protocol.py
@@ -16,9 +16,8 @@ import pandas as pd
 
 from .utils.enum import enum
 
-from zipline._protocol import BarData as _BarData
+from zipline._protocol import BarData  # noqa
 
-BarData = _BarData
 
 # Datasource type should completely determine the other fields of a
 # message with its type.
diff --git a/zipline/testing/core.py b/zipline/testing/core.py
index 4a236a3f..8a99b8d2 100644
--- a/zipline/testing/core.py
+++ b/zipline/testing/core.py
@@ -45,7 +45,8 @@ from zipline.utils.tradingcalendar import trading_days
 import numpy as np
 from numpy import (
     float64,
-    uint32
+    uint32,
+    int64,
 )
 
 
@@ -456,8 +457,9 @@ def make_trade_data_for_asset_info(dates,
     sids = asset_info.keys()
     date_field = 'day' if frequency == 'daily' else 'dt'
 
-    price_sid_deltas = np.arange(len(sids), dtype=float) * price_step_by_sid
-    price_date_deltas = np.arange(len(dates), dtype=float) * price_step_by_date
+    price_sid_deltas = np.arange(len(sids), dtype=float64) * price_step_by_sid
+    price_date_deltas = (np.arange(len(dates), dtype=float64) *
+                         price_step_by_date)
     prices = (price_sid_deltas + price_date_deltas[:, None]) + price_start
 
     volume_sid_deltas = np.arange(len(sids)) * volume_step_by_sid
@@ -723,8 +725,9 @@ class DailyBarWriterFromDataFrames(BcolzDailyBarWriter):
             return array.astype(uint32)
         elif colname == 'day':
             nanos_per_second = (1000 * 1000 * 1000)
-            self.check_uint_safe(arrmax.view(int) / nanos_per_second, colname)
-            return (array.view(int) / nanos_per_second).astype(uint32)
+            self.check_uint_safe(arrmax.view(int64) / nanos_per_second,
+                                 colname)
+            return (array.view(int64) / nanos_per_second).astype(uint32)
 
     @staticmethod
     def check_uint_safe(value, colname):
@@ -1198,8 +1201,8 @@ def create_mock_adjustments(tempdir, days, splits=None, dividends=None,
             'pay_date': np.array([], dtype='datetime64[ns]'),
             'record_date': np.array([], dtype='datetime64[ns]'),
             'declared_date': np.array([], dtype='datetime64[ns]'),
-            'amount': np.array([], dtype=float),
-            'sid': np.array([], dtype=int),
+            'amount': np.array([], dtype=float64),
+            'sid': np.array([], dtype=int64),
         }
         dividends = pd.DataFrame(
             data,
@@ -1360,9 +1363,9 @@ def create_empty_splits_mergers_frame():
     return pd.DataFrame(
         {
             # Hackery to make the dtypes correct on an empty frame.
-            'effective_date': np.array([], dtype=int),
-            'ratio': np.array([], dtype=float),
-            'sid': np.array([], dtype=int),
+            'effective_date': np.array([], dtype=int64),
+            'ratio': np.array([], dtype=float64),
+            'sid': np.array([], dtype=int64),
         },
         index=pd.DatetimeIndex([]),
         columns=['effective_date', 'ratio', 'sid'],
diff --git a/zipline/utils/compat.py b/zipline/utils/compat.py
deleted file mode 100644
index d0a037c9..00000000
--- a/zipline/utils/compat.py
+++ /dev/null
@@ -1,7 +0,0 @@
-from six import PY2
-
-
-if PY2:
-    from functools32 import lru_cache  # noqa
-else:
-    from functools import lru_cache  # noqa
diff --git a/zipline/utils/memoize.py b/zipline/utils/memoize.py
index 1b6a4bf1..f0c77f3d 100644
--- a/zipline/utils/memoize.py
+++ b/zipline/utils/memoize.py
@@ -1,8 +1,13 @@
 """
 Tools for memoization of function results.
 """
-from zipline.utils.compat import lru_cache
-from weakref import WeakKeyDictionary
+from collections import OrderedDict, Sequence
+from functools import wraps
+from itertools import compress
+from weakref import WeakKeyDictionary, ref
+
+from six.moves._thread import allocate_lock as Lock
+from toolz.sandbox import unzip
 
 
 class lazyval(object):
@@ -84,4 +89,211 @@ class classlazyval(lazyval):
         return super(classlazyval, self).__get__(owner, owner)
 
 
-remember_last = lru_cache(1)
+def _weak_lru_cache(maxsize=100):
+    """
+    Users should only access the lru_cache through its public API:
+    cache_info, cache_clear
+    The internals of the lru_cache are encapsulated for thread safety and
+    to allow the implementation to change.
+    """
+    def decorating_function(
+            user_function, tuple=tuple, sorted=sorted, len=len,
+            KeyError=KeyError):
+
+        hits, misses = [0], [0]
+        kwd_mark = (object(),)    # separates positional and keyword args
+        lock = Lock()             # needed because OrderedDict isn't threadsafe
+
+        if maxsize is None:
+            cache = _WeakArgsDict()  # cache without ordering or size limit
+
+            @wraps(user_function)
+            def wrapper(*args, **kwds):
+                key = args
+                if kwds:
+                    key += kwd_mark + tuple(sorted(kwds.items()))
+                try:
+                    result = cache[key]
+                    hits[0] += 1
+                    return result
+                except KeyError:
+                    pass
+                result = user_function(*args, **kwds)
+                cache[key] = result
+                misses[0] += 1
+                return result
+        else:
+            # ordered least recent to most recent
+            cache = _WeakArgsOrderedDict()
+            cache_popitem = cache.popitem
+            cache_renew = cache.move_to_end
+
+            @wraps(user_function)
+            def wrapper(*args, **kwds):
+                key = args
+                if kwds:
+                    key += kwd_mark + tuple(sorted(kwds.items()))
+                with lock:
+                    try:
+                        result = cache[key]
+                        cache_renew(key)    # record recent use of this key
+                        hits[0] += 1
+                        return result
+                    except KeyError:
+                        pass
+                result = user_function(*args, **kwds)
+                with lock:
+                    cache[key] = result     # record recent use of this key
+                    misses[0] += 1
+                    if len(cache) > maxsize:
+                        # purge least recently used cache entry
+                        cache_popitem(False)
+                return result
+
+        def cache_info():
+            """Report cache statistics"""
+            with lock:
+                return hits[0], misses[0], maxsize, len(cache)
+
+        def cache_clear():
+            """Clear the cache and cache statistics"""
+            with lock:
+                cache.clear()
+                hits[0] = misses[0] = 0
+
+        wrapper.cache_info = cache_info
+        wrapper.cache_clear = cache_clear
+        return wrapper
+
+    return decorating_function
+
+
+class _WeakArgs(Sequence):
+    """
+    Works with _WeakArgsDict to provide a weak cache for function args.
+    When any of those args are gc'd, the pair is removed from the cache.
+    """
+    def __init__(self, items, dict_remove=None):
+        def remove(k, selfref=ref(self), dict_remove=dict_remove):
+            self = selfref()
+            if self is not None and dict_remove is not None:
+                dict_remove(self)
+
+        self._items, self._selectors = unzip(self._try_ref(item, remove)
+                                             for item in items)
+        self._items = tuple(self._items)
+        self._selectors = tuple(self._selectors)
+
+    def __getitem__(self, index):
+        return self._items[index]
+
+    def __len__(self):
+        return len(self._items)
+
+    @staticmethod
+    def _try_ref(item, callback):
+        try:
+            return ref(item, callback), True
+        except TypeError:
+            return item, False
+
+    @property
+    def alive(self):
+        return all(item() is not None
+                   for item in compress(self._items, self._selectors))
+
+    def __eq__(self, other):
+        return self._items == other._items
+
+    def __hash__(self):
+        try:
+            return self.__hash
+        except AttributeError:
+            h = self.__hash = hash(self._items)
+            return h
+
+
+class _WeakArgsDict(WeakKeyDictionary, object):
+    def __delitem__(self, key):
+        del self.data[_WeakArgs(key)]
+
+    def __getitem__(self, key):
+        return self.data[_WeakArgs(key)]
+
+    def __repr__(self):
+        return '%s(%r)' % (type(self).__name__, self.data)
+
+    def __setitem__(self, key, value):
+        self.data[_WeakArgs(key, self._remove)] = value
+
+    def __contains__(self, key):
+        try:
+            wr = _WeakArgs(key)
+        except TypeError:
+            return False
+        return wr in self.data
+
+    def pop(self, key, *args):
+        return self.data.pop(_WeakArgs(key), *args)
+
+
+class _WeakArgsOrderedDict(_WeakArgsDict, object):
+    def __init__(self):
+        super(_WeakArgsOrderedDict, self).__init__()
+        self.data = OrderedDict()
+
+    def popitem(self, last=True):
+        while True:
+            key, value = self.data.popitem(last)
+            if key.alive:
+                return tuple(key), value
+
+    def move_to_end(self, key):
+        """Move an existing element to the end.
+
+        Raises KeyError if the element does not exist.
+        """
+        self[key] = self.pop(key)
+
+
+def weak_lru_cache(maxsize=100):
+    """Weak least-recently-used cache decorator.
+
+    If *maxsize* is set to None, the LRU features are disabled and the cache
+    can grow without bound.
+
+    Arguments to the cached function must be hashable. Any that are weak-
+    referenceable will be stored by weak reference.  Once any of the args have
+    been garbage collected, the entry will be removed from the cache.
+
+    View the cache statistics named tuple (hits, misses, maxsize, currsize)
+    with f.cache_info().  Clear the cache and statistics with f.cache_clear().
+
+    See:  http://en.wikipedia.org/wiki/Cache_algorithms#Least_Recently_Used
+
+    """
+    class desc(lazyval):
+        def __get__(self, instance, owner):
+            if instance is None:
+                return self
+            try:
+                return self._cache[instance]
+            except KeyError:
+                inst = ref(instance)
+
+                @_weak_lru_cache(maxsize)
+                @wraps(self._get)
+                def wrapper(*args, **kwargs):
+                    return self._get(inst(), *args, **kwargs)
+
+                self._cache[instance] = wrapper
+                return wrapper
+
+        @_weak_lru_cache(maxsize)
+        def __call__(self, *args, **kwargs):
+            return self._get(*args, **kwargs)
+
+    return desc
+
+
+remember_last = weak_lru_cache(1)