[jira] [Created] (ACCUMULO-909) NPE thrown for tablet readahead thread

["Josh Elser (JIRA)" <ji...@apache.org>]

Josh Elser created ACCUMULO-909:
-----------------------------------

             Summary: NPE thrown for tablet readahead thread
                 Key: ACCUMULO-909
                 URL: https://issues.apache.org/jira/browse/ACCUMULO-909
             Project: Accumulo
          Issue Type: Improvement
          Components: tserver
    Affects Versions: 1.5.0
         Environment: CentOS-5.7, Oracle Java 1.6.0_30
            Reporter: Josh Elser
            Assignee: Keith Turner
            Priority: Minor


I've had the below log snippet happen to me a couple of times while running continuous ingest. It doesn't appear to cause any issues, but it pops up annoyingly on the monitor. The context around the stacktrace in the log seems to be a new native map being allocated, a statement about a minor compaction starting, the NPE, and then the deallocation of the previous native map. I don't know enough about what actually is happening (or if my previous understanding is even an accurate cause), but I'd be happy to investigate deeper if someone can provide some guidance/understanding.

{noformat}
2012-12-16 21:02:02,822 [tabletserver.NativeMap] DEBUG: Allocated native map 0x00002aaaee88a8e0
2012-12-16 21:02:02,822 [tabletserver.MinorCompactor] DEBUG: Begin minor compaction /accumulo/tables/n/t-0001idd/F0001ivx.rf_tmp n;3;25
2012-12-16 21:02:02,895 [util.NamingThreadFactory] ERROR: Thread "tablet read ahead 15" died null
java.lang.NullPointerException
        at org.apache.accumulo.server.tabletserver.TabletServer$ThriftClientHandler$NextBatchTask.run(TabletServer.java:959)
        at org.apache.accumulo.cloudtrace.instrument.TraceRunnable.run(TraceRunnable.java:47)
        at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
        at org.apache.accumulo.cloudtrace.instrument.TraceRunnable.run(TraceRunnable.java:47)
        at org.apache.accumulo.core.util.LoggingRunnable.run(LoggingRunnable.java:34)
        at java.lang.Thread.run(Thread.java:662)
2012-12-16 21:02:02,913 [tabletserver.TabletServer] DEBUG: UpSess null 12,565 in 0.547s, at=[0 0 0.00 2] ft=0.464s(pt=0.123s lt=0.184s ct=0.157s)
2012-12-16 21:02:02,907 [tabletserver.TabletServer] DEBUG: UpSess null 12,373 in 0.544s, at=[0 0 0.00 2] ft=0.447s(pt=0.120s lt=0.186s ct=0.141s)
2012-12-16 21:02:02,943 [tabletserver.TabletServer] DEBUG: Failures: 1, first extent n;3;25 successful commits: 0
2012-12-16 21:02:02,955 [tabletserver.TabletServer] DEBUG: Failures: 1, first extent n;3;25 successful commits: 0
2012-12-16 21:02:03,050 [tabletserver.LargestFirstMemoryManager] DEBUG: BEFORE compactionThreshold = 0.627 maxObserved = 644,460,454
2012-12-16 21:02:03,050 [tabletserver.LargestFirstMemoryManager] DEBUG: AFTER compactionThreshold = 0.689
2012-12-16 21:21:55,587 [tabletserver.Compactor] DEBUG: Compaction n;4a81;47c09 45,951 read | 45,951 written | 178,797 entries/sec |  0.257 secs
2012-12-16 21:21:55,590 [tabletserver.Tablet] DEBUG: Logs for memory compacted: n;4a81;47c09 10.10.32.123+9997/ef83a2e7-f6e6-481c-8351-ae8b623c96e6
2012-12-16 21:21:55,595 [log.TabletServerLogger] DEBUG:  wrote MinC finish  36231: writeTime:0ms 
2012-12-16 21:21:55,596 [tabletserver.Tablet] TABLET_HIST: n;4a81;47c09 MinC [memory] -> /t-0001iw3/F0001ixf.rf
2012-12-16 21:21:55,596 [tabletserver.Tablet] DEBUG: MinC finish lock 0.00 secs n;4a81;47c09
2012-12-16 21:21:55,596 [tabletserver.NativeMap] DEBUG: Deallocating native map 0x00002aaab82f71b0
2012-12-16 21:21:55,633 [tabletserver.NativeMap] DEBUG: Deallocating native map 0x00002aab13fe7f10
{noformat}

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