hbase-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Anoop Sam John (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-18085) Prevent parallel purge in ObjectPool
Date Mon, 22 May 2017 07:59:04 GMT

    [ https://issues.apache.org/jira/browse/HBASE-18085?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16019246#comment-16019246
] 

Anoop Sam John commented on HBASE-18085:
----------------------------------------

Reading the code in ReentrantLock#tryLock(), I can see it uses a state variable up in the
layer in AbstractQueuedSynchronizer which is declared volatile.
{code}
/**
     * The synchronization state.
     */
    private volatile int state;
{code}
So we ourselves using a boolean volatile will be better any way right?  Pls check once whether
I misread some code path,

> 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
(v6.3.15#6346)

Mime
View raw message