[jira] [Created] (FLINK-24302) Direct buffer memory leak on Pulsar connector with Java 11

["Yufan Sheng (Jira)" <ji...@apache.org>]

Yufan Sheng created FLINK-24302:
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             Summary: Direct buffer memory leak on Pulsar connector with Java 11
                 Key: FLINK-24302
                 URL: https://issues.apache.org/jira/browse/FLINK-24302
             Project: Flink
          Issue Type: Bug
          Components: Connectors / Pulsar
    Affects Versions: 1.14.0
            Reporter: Yufan Sheng


Running the Pulsar connector with multiple split readers on Java 11 could throw {{a java.lang.OutOfMemoryError exception}}.

 
{code:java}
Caused by: java.util.concurrent.CompletionException: org.apache.pulsar.client.admin.internal.http.AsyncHttpConnector$RetryException: Could not complete the operation. Number of retries has been exhausted. Failed reason: java.lang.OutOfMemoryError: Direct buffer memory
	at java.base/java.util.concurrent.CompletableFuture.encodeThrowable(CompletableFuture.java:331)
	at java.base/java.util.concurrent.CompletableFuture.completeThrowable(CompletableFuture.java:346)
	at java.base/java.util.concurrent.CompletableFuture$OrApply.tryFire(CompletableFuture.java:1503)
	... 42 more
Caused by: org.apache.pulsar.client.admin.internal.http.AsyncHttpConnector$RetryException: Could not complete the operation. Number of retries has been exhausted. Failed reason: java.lang.OutOfMemoryError: Direct buffer memory
	at org.apache.pulsar.client.admin.internal.http.AsyncHttpConnector.lambda$retryOperation$4(AsyncHttpConnector.java:249)
	... 39 more
Caused by: org.apache.pulsar.shade.io.netty.handler.codec.EncoderException: java.lang.OutOfMemoryError: Direct buffer memory
	at org.apache.pulsar.shade.io.netty.handler.codec.MessageToMessageEncoder.write(MessageToMessageEncoder.java:104)
	at org.apache.pulsar.shade.io.netty.channel.CombinedChannelDuplexHandler.write(CombinedChannelDuplexHandler.java:346)
	at org.apache.pulsar.shade.io.netty.channel.AbstractChannelHandlerContext.invokeWrite0(AbstractChannelHandlerContext.java:717)
	at org.apache.pulsar.shade.io.netty.channel.AbstractChannelHandlerContext.invokeWrite(AbstractChannelHandlerContext.java:709)
	at org.apache.pulsar.shade.io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:792)
	at org.apache.pulsar.shade.io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:702)
	at org.apache.pulsar.shade.io.netty.handler.stream.ChunkedWriteHandler.doFlush(ChunkedWriteHandler.java:303)
	at org.apache.pulsar.shade.io.netty.handler.stream.ChunkedWriteHandler.flush(ChunkedWriteHandler.java:132)
	at org.apache.pulsar.shade.io.netty.channel.AbstractChannelHandlerContext.invokeFlush0(AbstractChannelHandlerContext.java:750)
	at org.apache.pulsar.shade.io.netty.channel.AbstractChannelHandlerContext.invokeWriteAndFlush(AbstractChannelHandlerContext.java:765)
	at org.apache.pulsar.shade.io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:790)
	at org.apache.pulsar.shade.io.netty.channel.AbstractChannelHandlerContext.writeAndFlush(AbstractChannelHandlerContext.java:758)
	at org.apache.pulsar.shade.io.netty.channel.DefaultChannelPipeline.writeAndFlush(DefaultChannelPipeline.java:1020)
	at org.apache.pulsar.shade.io.netty.channel.AbstractChannel.writeAndFlush(AbstractChannel.java:311)
	at org.apache.pulsar.shade.org.asynchttpclient.netty.request.NettyRequestSender.writeRequest(NettyRequestSender.java:420)
	... 23 more
{code}

The reason is that under Java 11, the Netty will allocate memory from the pool of Java Direct Memory and is affected by the MaxDirectMemory limit. Under Java 8, it allocates native memory and is not affected by that setting.

We have to reduce the direct memory usage by using a newer Pulsar client which has a memory-limits configuration.

This issue is addressed on Pulsar, and [PIP-74|https://github.com/apache/pulsar/wiki/PIP-74%3A-Pulsar-client-memory-limits] has been created for resolving this issue.

We should keep this issue open with no resolved versions until Pulsar provides a new client with memory limits.



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