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From "Josh Elser (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (ACCUMULO-4405) GC collection cycle stuck on waitForFlush RPC to Master
Date Mon, 15 Aug 2016 18:21:20 GMT

    [ https://issues.apache.org/jira/browse/ACCUMULO-4405?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15421415#comment-15421415
] 

Josh Elser commented on ACCUMULO-4405:
--------------------------------------

Welp, I guess this got busted with the Java changes by infra. I'll have to revisit.

> GC collection cycle stuck on waitForFlush RPC to Master
> -------------------------------------------------------
>
>                 Key: ACCUMULO-4405
>                 URL: https://issues.apache.org/jira/browse/ACCUMULO-4405
>             Project: Accumulo
>          Issue Type: Bug
>          Components: gc, master
>    Affects Versions: 1.7.1, 1.7.2
>            Reporter: Josh Elser
>            Assignee: Josh Elser
>             Fix For: 1.7.3, 1.8.1
>
>         Attachments: ACCUMULO-4405.001-1.7.patch
>
>
> While testing out 1.8.0rc1, all of the TabletServers had crashed due to an OOME, I believe,
because I temporarily ran out of HDFS space because HDFS trash was enabled (trash could not
be cleaned up fast enough for Accumulo generating more trash). I came back to the system after
restarting the TabletServers and found that the GC had not run a new cycle after restarting
the TabletServers. In a jstack of the GC, I saw:
> {noformat}
> "gc" #13 prio=5 os_prio=0 tid=0x00000000021f3800 nid=0x4dd5 runnable [0x00007f6f1ebc0000]
>    java.lang.Thread.State: RUNNABLE
>         at java.net.SocketInputStream.socketRead0(Native Method)
>         at java.net.SocketInputStream.socketRead(SocketInputStream.java:116)
>         at java.net.SocketInputStream.read(SocketInputStream.java:170)
>         at java.net.SocketInputStream.read(SocketInputStream.java:141)
>         at java.io.BufferedInputStream.fill(BufferedInputStream.java:246)
>         at java.io.BufferedInputStream.read1(BufferedInputStream.java:286)
>         at java.io.BufferedInputStream.read(BufferedInputStream.java:345)
>         - locked <0x00000000f5b4b750> (a java.io.BufferedInputStream)
>         at org.apache.thrift.transport.TIOStreamTransport.read(TIOStreamTransport.java:127)
>         at org.apache.thrift.transport.TTransport.readAll(TTransport.java:86)
>         at org.apache.thrift.transport.TFramedTransport.readFrame(TFramedTransport.java:129)
>         at org.apache.thrift.transport.TFramedTransport.read(TFramedTransport.java:101)
>         at org.apache.thrift.transport.TTransport.readAll(TTransport.java:86)
>         at org.apache.accumulo.core.client.impl.ThriftTransportPool$CachedTTransport.readAll(ThriftTransportPool.java:270)
>         at org.apache.thrift.protocol.TCompactProtocol.readByte(TCompactProtocol.java:634)
>         at org.apache.thrift.protocol.TCompactProtocol.readMessageBegin(TCompactProtocol.java:501)
>         at org.apache.thrift.TServiceClient.receiveBase(TServiceClient.java:77)
>         at org.apache.accumulo.core.master.thrift.MasterClientService$Client.recv_waitForFlush(MasterClientService.java:209)
>         at org.apache.accumulo.core.master.thrift.MasterClientService$Client.waitForFlush(MasterClientService.java:190)
>         at org.apache.accumulo.core.client.impl.TableOperationsImpl._flush(TableOperationsImpl.java:820)
>         at org.apache.accumulo.core.client.impl.TableOperationsImpl.compact(TableOperationsImpl.java:758)
>         at org.apache.accumulo.core.client.impl.TableOperationsImpl.compact(TableOperationsImpl.java:727)
>         at org.apache.accumulo.core.client.impl.TableOperationsImpl.compact(TableOperationsImpl.java:721)
>         at org.apache.accumulo.gc.SimpleGarbageCollector.run(SimpleGarbageCollector.java:592)
>         at org.apache.accumulo.gc.SimpleGarbageCollector.main(SimpleGarbageCollector.java:160)
>         at org.apache.accumulo.gc.GCExecutable.execute(GCExecutable.java:34)
>         at org.apache.accumulo.start.Main$1.run(Main.java:120)
>         at java.lang.Thread.run(Thread.java:745)
>    Locked ownable synchronizers:
>         - None
> {noformat}
> The Master was also stuck with an active thread/RPC:
> {noformat}
> "ClientPool 23257" #45412 daemon prio=5 os_prio=0 tid=0x00000000049cc000 nid=0x6401 waiting
on condition [0x00007f8462d94000]
>    java.lang.Thread.State: TIMED_WAITING (sleeping)
>         at java.lang.Thread.sleep(Native Method)
>         at org.apache.accumulo.core.client.impl.ThriftScanner.pause(ThriftScanner.java:211)
>         at org.apache.accumulo.core.client.impl.ThriftScanner.scan(ThriftScanner.java:259)
>         at org.apache.accumulo.core.client.impl.ScannerIterator$Reader.run(ScannerIterator.java:79)
>         at org.apache.accumulo.core.client.impl.ScannerIterator.hasNext(ScannerIterator.java:150)
>         at org.apache.accumulo.core.client.IsolatedScanner$RowBufferingIterator.readRow(IsolatedScanner.java:70)
>         at org.apache.accumulo.core.client.IsolatedScanner$RowBufferingIterator.<init>(IsolatedScanner.java:149)
>         at org.apache.accumulo.core.client.IsolatedScanner.iterator(IsolatedScanner.java:238)
>         at org.apache.accumulo.core.client.RowIterator.<init>(RowIterator.java:117)
>         at org.apache.accumulo.master.MasterClientServiceHandler.waitForFlush(MasterClientServiceHandler.java:188)
>         at sun.reflect.GeneratedMethodAccessor8.invoke(Unknown Source)
>         at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
>         at java.lang.reflect.Method.invoke(Method.java:497)
>         at org.apache.accumulo.core.trace.wrappers.RpcServerInvocationHandler.invoke(RpcServerInvocationHandler.java:46)
>         at org.apache.accumulo.server.rpc.RpcWrapper$1.invoke(RpcWrapper.java:74)
>         at com.sun.proxy.$Proxy18.waitForFlush(Unknown Source)
>         at org.apache.accumulo.core.master.thrift.MasterClientService$Processor$waitForFlush.getResult(MasterClientService.java:1436)
>         at org.apache.accumulo.core.master.thrift.MasterClientService$Processor$waitForFlush.getResult(MasterClientService.java:1420)
>         at org.apache.thrift.ProcessFunction.process(ProcessFunction.java:39)
>         at org.apache.thrift.TBaseProcessor.process(TBaseProcessor.java:39)
>         at org.apache.accumulo.server.rpc.TimedProcessor.process(TimedProcessor.java:63)
>         at org.apache.thrift.server.AbstractNonblockingServer$FrameBuffer.invoke(AbstractNonblockingServer.java:518)
>         at org.apache.accumulo.server.rpc.CustomNonBlockingServer$CustomFrameBuffer.invoke(CustomNonBlockingServer.java:106)
>         at org.apache.thrift.server.Invocation.run(Invocation.java:18)
>         at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
>         at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
>         at org.apache.accumulo.fate.util.LoggingRunnable.run(LoggingRunnable.java:35)
>         at java.lang.Thread.run(Thread.java:745)
>    Locked ownable synchronizers:
>         - <0x00000006caeb94d8> (a java.util.concurrent.ThreadPoolExecutor$Worker)
> {noformat}
> It would appear that in the {{waitForFlush}} implementation in MasterClientServiceHandler,
we construct a scanner (with the default timeout) and wrap an IsolatedScanner around that.
We do not set the timeout on the scanner which ends up using a default value of {{Long.MAX_VALUE}}
(essentially, never time out).
> The problem is that in ThriftScanner, the backoff policy for retrying the failed RPC's
starts at 100ms and then, for each subsequent retry loop, doubles the previous value (+/-
10%). In the face of a prolonged inability to scan a Tablet, the value we sleep grows: 100,
~200, ~400, ~800, ~1600ms, etc.
> Because the scan will not time out until Long.MAX_VALUE, we've essentially create an
RPC which never times out. We should apply an upper-limit, on the order of seconds, to the
maximum amount of time that ThriftScanner will sleep before retrying (without needing to change
the overall timeout property)



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