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https://issues.apache.org/jira/browse/HBASE-25899?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Xiaolin Ha resolved HBASE-25899.
--------------------------------
Fix Version/s: 2.5.0
3.0.0-alpha-1
Resolution: Fixed
> Improve efficiency of SnapshotHFileCleaner
> ------------------------------------------
>
> Key: HBASE-25899
> URL: https://issues.apache.org/jira/browse/HBASE-25899
> Project: HBase
> Issue Type: Improvement
> Components: master
> Affects Versions: 3.0.0-alpha-1, 2.0.0
> Reporter: Xiaolin Ha
> Assignee: Xiaolin Ha
> Priority: Major
> Fix For: 3.0.0-alpha-1, 2.5.0
>
> Attachments: 78631.jstack, cleaner-result.png
>
>
> We have met same problems of thousands threads in HBASE-22867, but after this
> issue, the cleaner becomes more inefficient.
> From the jstack we can see that most dir-scan threads are blocked at
> SnapshotHFileCleaner#getDeletableFiles,
> {code:java}
> "dir-scan-pool-19" #694 daemon prio=5 os_prio=0 tid=0x0000000002ab1800
> nid=0x26a7e waiting for monitor entry [0x00007fb0a9913000]
> java.lang.Thread.State: BLOCKED (on object monitor)
> at
> org.apache.hadoop.hbase.master.snapshot.SnapshotHFileCleaner.getDeletableFiles(SnapshotHFileCleaner.java:74)
> - waiting to lock <0x00007fb148737048> (a
> org.apache.hadoop.hbase.master.snapshot.SnapshotHFileCleaner)
> at
> org.apache.hadoop.hbase.master.cleaner.CleanerChore.checkAndDeleteFiles(CleanerChore.java:498)
> at
> org.apache.hadoop.hbase.master.cleaner.CleanerChore.lambda$traverseAndDelete$1(CleanerChore.java:246)
> at
> org.apache.hadoop.hbase.master.cleaner.CleanerChore$$Lambda$41/1187372779.act(Unknown
> Source)
> at
> org.apache.hadoop.hbase.master.cleaner.CleanerChore.deleteAction(CleanerChore.java:358)
> at
> org.apache.hadoop.hbase.master.cleaner.CleanerChore.traverseAndDelete(CleanerChore.java:246)
> at
> org.apache.hadoop.hbase.master.cleaner.CleanerChore.lambda$null$2(CleanerChore.java:255)
> at
> org.apache.hadoop.hbase.master.cleaner.CleanerChore$$Lambda$38/2003131501.run(Unknown
> Source)
> at
> java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
> at java.lang.Thread.run(Thread.java:745){code}
> and all the HFileCleaner threads are waiting at the delete tasks queue,
> {code:java}
> "gha-data-hbase0002:16000.activeMasterManager-HFileCleaner.large.2-1621210982419"
> #358 daemon prio=5 os_prio=0 tid=0x00007fb967fc0000 nid=0x266f2 waiting on
> condition [0x00007fb0c57d6000]
> java.lang.Thread.State: WAITING (parking)
> at sun.misc.Unsafe.park(Native Method)
> - parking to wait for <0x00007fb1486db9f0> (a
> java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
> at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
> at
> java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
> at
> org.apache.hadoop.hbase.util.StealJobQueue.take(StealJobQueue.java:106)
> at
> org.apache.hadoop.hbase.master.cleaner.HFileCleaner.consumerLoop(HFileCleaner.java:264)
> at
> org.apache.hadoop.hbase.master.cleaner.HFileCleaner$1.run(HFileCleaner.java:233)
> {code}
> So it's need to increase the speed of scanning files. But since the
> getDeletableFiles is a synchronized method, increasing the number of scan-dir
> threads can not solve this problem.
> After looking through the codes in SnapshotHFileCleaner and
> SnapshotFileCache, I think the lock granularity in them should be optimized.
>
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