[GitHub] [rocketmq] cserwen edited a comment on issue #3491: [POP] When only consuming but not producing, the pull request may be held by broker

[GitBox <gi...@apache.org>]

cserwen edited a comment on issue #3491:
URL: https://github.com/apache/rocketmq/issues/3491#issuecomment-971255903


   > I agree with you, but I think the main function of this lock is to save the offset scene at the time when the offset is rolled back, which is convenient for checking the problem, it does increase the lock competition. Do you have a better way to balance performance and problem site information?
   
   I don't understand when the offset rollback will happen, so I can't get the effect of this lock. 
   I have a solution that we can use the `PopLongPollingService` thread to scan the requests in the `pollingMap` to determine if the locks corresponding to those requests can be acquired, and if possible, we will `wakeUp` these requests in advance.
   ```java
   if (!PopMessageProcessor.this.queueLockManager.isLock(key)) {  
       totalPollingNum.decrementAndGet();
       wakeUp(first);
       continue;
   }    //above lines.
   
   if (!first.isTimeout()) {
       if (popQ.add(first)) {
           break;
       } else {
           POP_LOGGER.info("polling, add fail again: {}", first);
       }
   }
   ```


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