Exception thrown during RedisClusterClient shutdown

[jdeppe-pivotal]

Bug Report

Current Behavior

While using lettuce against a cluster where nodes are being stopped and restarted, the following exception is thrown when the test shuts down the RedisClusterClient

    java.util.NoSuchElementException
        at java.util.concurrent.ConcurrentHashMap$KeyIterator.next(ConcurrentHashMap.java:3453)
        at io.lettuce.core.AbstractRedisClient.closeResources(AbstractRedisClient.java:551)
        at io.lettuce.core.AbstractRedisClient.shutdownAsync(AbstractRedisClient.java:540)
        at io.lettuce.core.cluster.RedisClusterClient.shutdownAsync(RedisClusterClient.java:1058)
        at io.lettuce.core.AbstractRedisClient.shutdown(AbstractRedisClient.java:504)
        at io.lettuce.core.AbstractRedisClient.shutdown(AbstractRedisClient.java:472)
        at org.apache.geode.redis.internal.executor.CrashAndNoRepeatDUnitTest.cleanup(CrashAndNoRepeatDUnitTest.java:110)```

Input Code

The RedisClusterClient is configured as follows:

    clusterClient = RedisClusterClient.create("redis://localhost:" + redisServerPort1);

    ClusterTopologyRefreshOptions refreshOptions =
        ClusterTopologyRefreshOptions.builder()
            .enableAllAdaptiveRefreshTriggers()
            .enablePeriodicRefresh(Duration.ofSeconds(5))
            .build();

    clusterClient.setOptions(ClusterClientOptions.builder()
        .topologyRefreshOptions(refreshOptions)
        .validateClusterNodeMembership(false)
        .build());

Expected behavior/code

shutdown should not produce any errors.

Environment

• Lettuce version(s): 6.1.3.RELEASE
• Redis version: custom

[mp911de]

I'm currently not sure where the bug is. shutdown isn't thread-safe to be called by multiple threads concurrently. We could copy over the closeable resources to an independent list instead of operating on the actual holder.

[jdeppe-pivotal]

Just to be clear - shutdown is only being called by a single thread.

[mp911de]

That's fixed now. Care to run tests against the latest snapshots (via https://oss.sonatype.org/content/repositories/snapshots/)?

[jdeppe-pivotal]

Looks like it's good now. Thanks again @mp911de !!