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https://issues.apache.org/jira/browse/ARTEMIS-1996?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16629398#comment-16629398
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ASF GitHub Bot commented on ARTEMIS-1996:
-----------------------------------------
Github user franz1981 commented on a diff in the pull request:
https://github.com/apache/activemq-artemis/pull/2250#discussion_r220720824
--- Diff:
artemis-journal/src/main/java/org/apache/activemq/artemis/core/journal/impl/JournalImpl.java
---
@@ -1796,15 +1826,15 @@ private synchronized JournalLoadInformation
load(final LoaderCallback loadManage
private void checkID(final long id) {
if (id > maxID.longValue()) {
- maxID.set(id);
+ maxID.lazySet(id);
--- End diff --
It's a fair concern, but If we are not single threaded here I'm quite sure
that both set/lazySet are wrong, given that none of them is addressing the
chance that others will do the same concurrently :)
But looking at the code maxID is being created and used with single
threaded semantic here, quoting the comments on the code:
`// AtomicLong is used only as a reference, not as an Atomic value
final AtomicLong maxID = new AtomicLong(-1); final AtomicLong
maxID = new AtomicLong(-1);`
> 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
> Priority: Minor
>
> 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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