[kafka] branch trunk updated: KAFKA-7660: Fix child sensor memory leak (#5974)

[gu...@apache.org]

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guozhang pushed a commit to branch trunk
in repository https://gitbox.apache.org/repos/asf/kafka.git


The following commit(s) were added to refs/heads/trunk by this push:
     new b7d95da  KAFKA-7660: Fix child sensor memory leak (#5974)
b7d95da is described below

commit b7d95da88df3a521870fa4f6d6e53cee7e679d40
Author: John Roesler <vv...@users.noreply.github.com>
AuthorDate: Thu Nov 29 22:10:24 2018 -0600

    KAFKA-7660: Fix child sensor memory leak (#5974)
    
    A heap dump provided by Patrik Kleindl in https://issues.apache.org/jira/browse/KAFKA-7660 identifies the childrenSensors map in Metrics as keeping references to sensors alive after they have been removed.
    
    This PR fixes it and adds a test to be sure.
    
    Reviewers: Jason Gustafson <ja...@confluent.io>, Guozhang Wang <wa...@gmail.com>
---
 .../java/org/apache/kafka/common/metrics/Metrics.java    |  5 +++++
 .../java/org/apache/kafka/common/metrics/Sensor.java     | 10 ++++++++--
 .../org/apache/kafka/common/metrics/MetricsTest.java     | 16 ++++++++++++++++
 3 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/clients/src/main/java/org/apache/kafka/common/metrics/Metrics.java b/clients/src/main/java/org/apache/kafka/common/metrics/Metrics.java
index a6da9f9..9e2b6f1 100644
--- a/clients/src/main/java/org/apache/kafka/common/metrics/Metrics.java
+++ b/clients/src/main/java/org/apache/kafka/common/metrics/Metrics.java
@@ -41,6 +41,8 @@ import java.util.concurrent.ScheduledThreadPoolExecutor;
 import java.util.concurrent.ThreadFactory;
 import java.util.concurrent.TimeUnit;
 
+import static java.util.Collections.emptyList;
+
 /**
  * A registry of sensors and metrics.
  * <p>
@@ -446,6 +448,9 @@ public class Metrics implements Closeable {
                             removeMetric(metric.metricName());
                         log.debug("Removed sensor with name {}", name);
                         childSensors = childrenSensors.remove(sensor);
+                        for (final Sensor parent : sensor.parents()) {
+                            childrenSensors.getOrDefault(parent, emptyList()).remove(sensor);
+                        }
                     }
                 }
             }
diff --git a/clients/src/main/java/org/apache/kafka/common/metrics/Sensor.java b/clients/src/main/java/org/apache/kafka/common/metrics/Sensor.java
index ccbe8aa..1af9419 100644
--- a/clients/src/main/java/org/apache/kafka/common/metrics/Sensor.java
+++ b/clients/src/main/java/org/apache/kafka/common/metrics/Sensor.java
@@ -22,7 +22,6 @@ import org.apache.kafka.common.utils.Time;
 import org.apache.kafka.common.utils.Utils;
 
 import java.util.ArrayList;
-import java.util.Collections;
 import java.util.HashSet;
 import java.util.LinkedHashMap;
 import java.util.LinkedList;
@@ -32,6 +31,9 @@ import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.TimeUnit;
 
+import static java.util.Arrays.asList;
+import static java.util.Collections.unmodifiableList;
+
 /**
  * A sensor applies a continuous sequence of numerical values to a set of associated metrics. For example a sensor on
  * message size would record a sequence of message sizes using the {@link #record(double)} api and would maintain a set
@@ -133,6 +135,10 @@ public final class Sensor {
         return this.name;
     }
 
+    List<Sensor> parents() {
+        return unmodifiableList(asList(parents));
+    }
+
     /**
      * Record an occurrence, this is just short-hand for {@link #record(double) record(1.0)}
      */
@@ -291,7 +297,7 @@ public final class Sensor {
     }
 
     synchronized List<KafkaMetric> metrics() {
-        return Collections.unmodifiableList(new LinkedList<>(this.metrics.values()));
+        return unmodifiableList(new LinkedList<>(this.metrics.values()));
     }
 
     /**
diff --git a/clients/src/test/java/org/apache/kafka/common/metrics/MetricsTest.java b/clients/src/test/java/org/apache/kafka/common/metrics/MetricsTest.java
index 3184aeb..98b468a 100644
--- a/clients/src/test/java/org/apache/kafka/common/metrics/MetricsTest.java
+++ b/clients/src/test/java/org/apache/kafka/common/metrics/MetricsTest.java
@@ -16,6 +16,8 @@
  */
 package org.apache.kafka.common.metrics;
 
+import static java.util.Collections.emptyList;
+import static java.util.Collections.singletonList;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotNull;
@@ -203,6 +205,20 @@ public class MetricsTest {
     }
 
     @Test
+    public void testRemoveChildSensor() {
+        final Metrics metrics = new Metrics();
+
+        final Sensor parent = metrics.sensor("parent");
+        final Sensor child = metrics.sensor("child", parent);
+
+        assertEquals(singletonList(child), metrics.childrenSensors().get(parent));
+
+        metrics.removeSensor("child");
+
+        assertEquals(emptyList(), metrics.childrenSensors().get(parent));
+    }
+
+    @Test
     public void testRemoveSensor() {
         int size = metrics.metrics().size();
         Sensor parent1 = metrics.sensor("test.parent1");