From b291dd44865ace133e5808cc221620b8f3290610 Mon Sep 17 00:00:00 2001
From: Simon Mo <simon.mo@hey.com>
Date: Tue, 15 Dec 2020 09:39:39 -0800
Subject: [PATCH] [Metrics] Call GetMeasureDoubleByName to prevent override
 (#12860)

---
 python/ray/tests/test_metrics_agent.py | 28 ++++++++++++++++++++++++++
 src/ray/stats/metric.cc                | 15 ++++++++++++--
 2 files changed, 41 insertions(+), 2 deletions(-)

diff --git a/python/ray/tests/test_metrics_agent.py b/python/ray/tests/test_metrics_agent.py
index 9386e4f1f..12490dd44 100644
--- a/python/ray/tests/test_metrics_agent.py
+++ b/python/ray/tests/test_metrics_agent.py
@@ -2,6 +2,7 @@ import json
 import pathlib
 import platform
 from pprint import pformat
+import time
 from unittest.mock import MagicMock
 
 import requests
@@ -293,6 +294,33 @@ def test_custom_metrics_edge_cases(metric_mock):
         Count("name", tag_keys=("a"))
 
 
+def test_metrics_override_shouldnt_warn(ray_start_regular, log_pubsub):
+    # https://github.com/ray-project/ray/issues/12859
+
+    @ray.remote
+    def override():
+        a = Count("num_count", description="")
+        b = Count("num_count", description="")
+        a.record(1)
+        b.record(1)
+
+    ray.get(override.remote())
+
+    # Check the stderr from the worker.
+    start = time.time()
+    while True:
+        if (time.time() - start) > 5:
+            break
+        msg = log_pubsub.get_message()
+        if msg is None:
+            time.sleep(0.01)
+            continue
+
+        log_lines = json.loads(ray.utils.decode(msg["data"]))["lines"]
+        for line in log_lines:
+            assert "Attempt to register measure" not in line
+
+
 if __name__ == "__main__":
     import sys
     sys.exit(pytest.main(["-v", __file__]))
diff --git a/src/ray/stats/metric.cc b/src/ray/stats/metric.cc
index 2cfe236b9..4a475a338 100644
--- a/src/ray/stats/metric.cc
+++ b/src/ray/stats/metric.cc
@@ -16,6 +16,7 @@
 
 #include "opencensus/stats/internal/aggregation_window.h"
 #include "opencensus/stats/internal/set_aggregation_window.h"
+#include "opencensus/stats/measure_registry.h"
 
 namespace ray {
 
@@ -78,14 +79,24 @@ bool StatsConfig::IsInitialized() const { return is_initialized_; }
 ///
 /// Metric
 ///
+using MeasureDouble = opencensus::stats::Measure<double>;
 void Metric::Record(double value, const TagsType &tags) {
   if (StatsConfig::instance().IsStatsDisabled()) {
     return;
   }
 
   if (measure_ == nullptr) {
-    measure_.reset(new opencensus::stats::Measure<double>(
-        opencensus::stats::Measure<double>::Register(name_, description_, unit_)));
+    // Measure could be registered before, so we try to get it first.
+    MeasureDouble registered_measure =
+        opencensus::stats::MeasureRegistry::GetMeasureDoubleByName(name_);
+
+    if (registered_measure.IsValid()) {
+      measure_.reset(new MeasureDouble(registered_measure));
+    } else {
+      measure_.reset(
+          new MeasureDouble(MeasureDouble::Register(name_, description_, unit_)));
+    }
+
     RegisterView();
   }