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https://issues.apache.org/jira/browse/ROCKETMQ-98?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15871352#comment-15871352
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ASF GitHub Bot commented on ROCKETMQ-98:
----------------------------------------

Github user shroman commented on a diff in the pull request:

    https://github.com/apache/incubator-rocketmq/pull/61#discussion_r101699903
  
    --- Diff: common/src/main/java/org/apache/rocketmq/common/BrokerConfig.java 
---
    @@ -47,6 +47,7 @@
         private boolean autoCreateSubscriptionGroup = true;
         private String messageStorePlugIn = "";
     
    +    //thread counts for sending message, if large number threads are 
needed, we suggest setting useReentrantLockWhenPutMessage=true(in 
MessageStoreConfig)
    --- End diff --
    
    Is this suggestion based on observations in RocketMQ production 
environments?


> Risk of unable to release putMessage Lock forever
> -------------------------------------------------
>
>                 Key: ROCKETMQ-98
>                 URL: https://issues.apache.org/jira/browse/ROCKETMQ-98
>             Project: Apache RocketMQ
>          Issue Type: Bug
>    Affects Versions: 4.1.0-incubating
>            Reporter: Jaskey Lam
>            Assignee: vongosling
>             Fix For: 4.1.0-incubating
>
>
> In current implemenation, there are two kind of locks dev can choose. If I 
> choose reentrantLock, and lock it then put message, in this time I change the 
> config through admin interface to use spin lock. When trying to unlock, 
> rocketmq will try to unlock the spin lock though actually the reentrantlock 
> is locked, this will cause the reentrantlock not able to release forever and 
> trying to release the wrong spin lock but actully it is not locked!
>     /**
>      * Spin util acquired the lock.
>      */
>     private void lockForPutMessage() {
>         if 
> (this.defaultMessageStore.getMessageStoreConfig().isUseReentrantLockWhenPutMessage())
>  {
>             putMessageNormalLock.lock();
>         } else {
>             boolean flag;
>             do {
>                 flag = this.putMessageSpinLock.compareAndSet(true, false);
>             }
>             while (!flag);
>         }
>     }
>     private void releasePutMessageLock() {
>         if 
> (this.defaultMessageStore.getMessageStoreConfig().isUseReentrantLockWhenPutMessage())
>  {
>             putMessageNormalLock.unlock();
>         } else {
>             this.putMessageSpinLock.compareAndSet(false, true);
>         }
>     }



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