[jira] [Created] (ZOOKEEPER-4360) Avoid NPE during metrics execution if the leader is not set on a FOLLOWER node

["Nicoló Boschi (Jira)" <ji...@apache.org>]

Nicoló Boschi created ZOOKEEPER-4360:
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             Summary: Avoid NPE during metrics execution if the leader is not set on a FOLLOWER node 
                 Key: ZOOKEEPER-4360
                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-4360
             Project: ZooKeeper
          Issue Type: Bug
          Components: metric system
    Affects Versions: 3.6.2
            Reporter: Nicoló Boschi
             Fix For: 3.7.1


On a follower node, we had this error

{code}
ago 20, 2021 1:46:28 PM org.apache.catalina.core.StandardWrapperValve invoke
GRAVE: Servlet.service() for servlet [metrics] in context with path [/metrics] threw exception
java.lang.NullPointerException: Cannot invoke "org.apache.zookeeper.server.quorum.Leader.getProposalStats()" because the return value of "org.apache.zookeeper.server.quorum.LeaderZooKeeperServer.getLeader()" is null
        at org.apache.zookeeper.server.quorum.LeaderZooKeeperServer.lambda$registerMetrics$5(LeaderZooKeeperServer.java:122)
        at magnews.zookeeper.ZooKeeperMetricsProviderAdapter$MetricsContextImpl.lambda$registerGauge$0(ZooKeeperMetricsProviderAdapter.java:91)
{code}

Unfortunately, I'm not able to reproduce this error deterministically
 




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