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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