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https://issues.apache.org/jira/browse/HBASE-13097?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14336635#comment-14336635
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Jurriaan Mous commented on HBASE-13097:
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I was certainly aware that having multiple connections is heavy. Thats why I
cleaned up a lot of Connections in the past in tests in HBASE-12796. It is
recommended by Netty to recycle EventLoopGroups for all bootstrap creation but
configurations could differ between connections so sharing them is not easy.
Maybe we could detect the usage of the same config options and recycle
RpcClients? The best option seems to be to limit the amount of AsyncRpcClient
and thus Connection creation.
[~Apache9] Are you sure each bootstrap has its own PooledByteBufAllocator?
Since the bootstrap creation links to the default static PooledByteBufAllocator
instance so it should be reused. I think you meant an abundant EventLoopGroup
creation which each has its own Thread pool.
{code:title=AsyncRpcClient.java|borderStyle=solid}
bootstrap.group(eventLoopGroup).channel(socketChannelClass)
.option(ChannelOption.ALLOCATOR, PooledByteBufAllocator.DEFAULT)
{code}
> Netty PooledByteBufAllocator cause OOM in some unit test
> --------------------------------------------------------
>
> Key: HBASE-13097
> URL: https://issues.apache.org/jira/browse/HBASE-13097
> Project: HBase
> Issue Type: Bug
> Components: IPC/RPC, test
> Affects Versions: 2.0.0, 1.1.0
> Reporter: zhangduo
>
> In some unit tests(such as TestAcidGuarantees) we create multiple Connection
> instance. If we use AsyncRpcClient, then there will be multiple netty
> Bootstrap and every Bootstrap has its own PooledByteBufAllocator.
> I haven't read the code clearly but it uses some threadlocal technics and
> jmap shows io.netty.buffer.PoolThreadCache$MemoryRegionCache$Entry is the
> biggest things on Heap.
> See
> https://builds.apache.org/job/HBase-TRUNK/6168/artifact/hbase-server/target/surefire-reports/org.apache.hadoop.hbase.TestAcidGuarantees-output.txt
> {noformat}
> 2015-02-24 23:50:29,704 WARN [JvmPauseMonitor]
> util.JvmPauseMonitor$Monitor(167): Detected pause in JVM or host machine (eg
> GC): pause of approximately 20133ms
> GC pool 'PS MarkSweep' had collection(s): count=15 time=55525ms
> {noformat}
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