hbase-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Yu Li (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-18085) Prevent parallel purge in ObjectPool
Date Tue, 23 May 2017 07:46:04 GMT

    [ https://issues.apache.org/jira/browse/HBASE-18085?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16020775#comment-16020775

Yu Li commented on HBASE-18085:

To summarize, volatile boolean is not suitable for this usage since this is not a "single
thread updating, multiple thread reading" case, while AtomicBoolean and ReentrantLock#tryLock
have similar performance according to JMH.

In theory AtomicBoolean is more light-weight, but JMH shows a similar perf, and in our project
tryLock is more frequently used for similar scenario, such as the {{BucketCache#freeSpaceLock}}
and {{MemstoreLABImpl#lock}}, etc. So I still suggest to follow the old way to use tryLock
here, but please feel free to raise different voice. Thanks.

> Prevent parallel purge in ObjectPool
> ------------------------------------
>                 Key: HBASE-18085
>                 URL: https://issues.apache.org/jira/browse/HBASE-18085
>             Project: HBase
>          Issue Type: Bug
>            Reporter: Yu Li
>            Assignee: Yu Li
>         Attachments: e89l05465.st3.jstack, HBASE-18085.patch
> Parallel purge in ObjectPool is meaningless and will cause contention issue since {{ReferenceQueue#poll}}
has synchronization (source code shown below)
> {code}
>     public Reference<? extends T> poll() {
>         if (head == null)
>             return null;
>         synchronized (lock) {
>             return reallyPoll();
>         }
>     }
> {code}
> We observed threads blocking on the purge method while using offheap bucket cache, and
we could easily reproduce this by testing the 100% cache hit case in bucket cache with enough
reading threads.
> We propose to add a purgeLock and use tryLock to avoid parallel purge.

This message was sent by Atlassian JIRA

View raw message