[jira] [Created] (ARTEMIS-1996) MappedSequentialFileFactory may cause DirectByteBuffer memory leaks

["tang pu (JIRA)" <ji...@apache.org>]

tang pu created ARTEMIS-1996:
--------------------------------

             Summary: MappedSequentialFileFactory may cause DirectByteBuffer memory leaks
                 Key: ARTEMIS-1996
                 URL: https://issues.apache.org/jira/browse/ARTEMIS-1996
             Project: ActiveMQ Artemis
          Issue Type: Bug
          Components: Broker
            Reporter: tang pu


Because of some customization requirements, the readJournalFile method of JournalImpl needs to be calledmultiple times. 

During the stress test, it was found that almost every 5 hours, the Broker appeared a Full GC.

This is the information about the Full GC in the GC log.

{color:#FF0000}2018-07-25T12:14:07.323+0800: 10089.523: [Full GC (System.gc()) 6767M->253M(16G), 8.7138691 secs]{color}
{color:#FF0000} [Eden: 632.0M(712.0M)->0.0B(816.0M) Survivors: 104.0M->0.0B Heap: 6767.6M(16.0G)->253.9M(16.0G)], [Metaspace: 36323K->35961K(1083392K)]{color}
{color:#FF0000} [Times: user=2.56 sys=0.42, real=8.71 secs] {color}

When the Full GC appears, the thread stack is as follows:

{color:#FF0000}java.lang.System.gc(System.java:993){color}
{color:#FF0000}java.nio.Bits.reserveMemory(Bits.java:666){color}
{color:#FF0000}java.nio.DirectByteBuffer.<init>(DirectByteBuffer.java:123){color}
{color:#FF0000}java.nio.ByteBuffer.allocateDirect(ByteBuffer.java:311){color}
{color:#FF0000}org.apache.activemq.artemis.core.io.mapped.MappedSequentialFileFactory.newBuffer(MappedSequentialFileFactory.java:109){color}
{color:#FF0000}org.apache.activemq.artemis.core.journal.impl.JournalImpl.readJournalFile(JournalImpl.java:463){color}

By analyzing the stack, it should be that the JVM's heap memory cannot be allocated, causing the JVM to call the System.gc() method.

In the Broker, MappedSequentialFileFactory caches off-heap memory through ThreadLocal. Once the thread is evicted by the CompactExecutor(keepalive is 60s) in the Journal, the heap memory is "leaked".

{color:#FF0000}NIOSequentialFileFactory{color} also has the same problem

 

 

 



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