[xray] Implement timeline and profiling API. (#2306)

* Add profile table and store profiling information there.

* Code for dumping timeline.

* Improve color scheme.

* Push timeline events on driver only for raylet.

* Improvements to profiling and timeline visualization

* Some linting

* Small fix.

* Linting

* Propagate node IP address through profiling events.

* Fix test.

* object_id.hex() should return byte string in python 2.

* Include gcs.fbs in node_manager.fbs.

* Remove flatbuffer definition duplication.

* Decode to unicode in Python 3 and bytes in Python 2.

* Minor

* Submit profile events in a batch. Revert some CMake changes.

* Fix

* Workaround test failure.

* Fix linting

* Linting

* Don't return anything from chrome_tracing_dump when filename is provided.

* Remove some redundancy from profile table.

* Linting

* Move TODOs out of docstring.

* Minor

python/ray/log_monitor.py

@@ -10,6 +10,7 @@ import time
 from ray.services import get_ip_address
 from ray.services import get_port
 from ray.services import logger
+import ray.utils
 
 
 class LogMonitor(object):
@@ -70,7 +71,7 @@ class LogMonitor(object):
                 if len(new_lines) > 0:
                     self.log_files[log_filename] += new_lines
                     redis_key = "LOGFILE:{}:{}".format(
-                        self.node_ip_address, log_filename.decode("ascii"))
+                        self.node_ip_address, ray.utils.decode(log_filename))
                     self.redis_client.rpush(redis_key, *new_lines)
 
             # Pass if we already failed to open the log file.