[HDDS-7349] Flaky integration test have memory leak for RatisDropwizardExports

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 1.4.0
• Labels: pull-request-available
• Assignee: Sumit Agrawal
• Reporter: Sumit Agrawal
• Created: 18/Oct/22 04:08
• Updated: 11/Nov/22 06:30
• Resolved: 26/Oct/22 18:12

Description

Memory leak observed in flaky integration test causing OutOfMemory multiple times, and causing the cancel of the case.

1. registeration of RatisDropwizardExports is done multiple time, even its registered.
– This is called by Ratis CopyOnWrite when another metrics get registered.
– Since the track of above object is lost, no way to cleanup later

------------------stack showing registeration-----------
  at io.prometheus.client.CollectorRegistry.register(Lio/prometheus/client/Collector;)V (CollectorRegistry.java:60)
  at org.apache.hadoop.hdds.server.http.RatisDropwizardExports.registerDropwizard(Lorg/apache/ratis/metrics/RatisMetricRegistry;Ljava/util/Map;)V (RatisDropwizardExports.java:75)
  at org.apache.hadoop.hdds.server.http.RatisDropwizardExports.lambda$registerRatisMetricReporters$0(Ljava/util/Map;Lorg/apache/ratis/metrics/RatisMetricRegistry;)V (RatisDropwizardExports.java:53)
  at org.apache.hadoop.hdds.server.http.RatisDropwizardExports$$Lambda$384.accept(Ljava/lang/Object;)V (Unknown Source)
  at org.apache.ratis.metrics.impl.MetricRegistriesImpl.lambda$null$0(Lorg/apache/ratis/metrics/RatisMetricRegistry;Ljava/util/function/Consumer;)V (MetricRegistriesImpl.java:72)
  at org.apache.ratis.metrics.impl.MetricRegistriesImpl$$Lambda$618.accept(Ljava/lang/Object;)V (Unknown Source)
  at java.util.concurrent.CopyOnWriteArrayList.forEach(Ljava/util/function/Consumer;)V (CopyOnWriteArrayList.java:895)
  at org.apache.ratis.metrics.impl.MetricRegistriesImpl.lambda$create$1(Lorg/apache/ratis/metrics/MetricRegistryInfo;)Lorg/apache/ratis/metrics/RatisMetricRegistry; (MetricRegistriesImpl.java:72)
------------------------------------

2. after stop of Datanode, still ratis registeration going on causing to get accumulated.

This is observed that Datanode is stopped, but still Datanode having "ratisMetricsMap" having new metrics registered.

Issue Links

• is related to: HDDS-7473 Ratis integration for support of remove registeration
• links to: GitHub Pull Request #3858