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Posted to dev@zookeeper.apache.org by "Laxman (JIRA)" <ji...@apache.org> on 2011/07/28 11:04:09 UTC
[jira] [Commented] (ZOOKEEPER-954) Findbugs/ClientCnxn: Bug type
JLM_JSR166_UTILCONCURRENT_MONITORENTER
[ https://issues.apache.org/jira/browse/ZOOKEEPER-954?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13072259#comment-13072259 ]
Laxman commented on ZOOKEEPER-954:
----------------------------------
Findbugs description for this says
"This method performs synchronization an object that implements java.util.concurrent.locks.Lock. Such an object is locked/unlocked using acquire()/release() rather than using the synchronized (...) construct."
But in our code[ClientCnxt] we used LinkedBlockingQueue [waitingEvents] which does not implement Lock. Also, from code it looks intentional and appropriate to synchronize waitingEvents explicitly to ensure no event is dropped from processing.
Any other thoughts on this?
> Findbugs/ClientCnxn: Bug type JLM_JSR166_UTILCONCURRENT_MONITORENTER
> --------------------------------------------------------------------
>
> Key: ZOOKEEPER-954
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-954
> Project: ZooKeeper
> Issue Type: Bug
> Components: java client
> Reporter: Thomas Koch
> Priority: Minor
>
> JLM Synchronization performed on java.util.concurrent.LinkedBlockingQueue in org.apache.zookeeper.ClientCnxn$EventThread.queuePacket(ClientCnxn$Packet)
>
> Bug type JLM_JSR166_UTILCONCURRENT_MONITORENTER (click for details)
> In class org.apache.zookeeper.ClientCnxn$EventThread
> In method org.apache.zookeeper.ClientCnxn$EventThread.queuePacket(ClientCnxn$Packet)
> Type java.util.concurrent.LinkedBlockingQueue
> Value loaded from field org.apache.zookeeper.ClientCnxn$EventThread.waitingEvents
> At ClientCnxn.java:[line 411]
> JLM Synchronization performed on java.util.concurrent.LinkedBlockingQueue in org.apache.zookeeper.ClientCnxn$EventThread.run()
>
> Bug type JLM_JSR166_UTILCONCURRENT_MONITORENTER (click for details)
> In class org.apache.zookeeper.ClientCnxn$EventThread
> In method org.apache.zookeeper.ClientCnxn$EventThread.run()
> Type java.util.concurrent.LinkedBlockingQueue
> Value loaded from field org.apache.zookeeper.ClientCnxn$EventThread.waitingEvents
> At ClientCnxn.java:[line 436]
> The respective code:
> 409 public void queuePacket(Packet packet) {
> 410 if (wasKilled) {
> 411 synchronized (waitingEvents) {
> 412 if (isRunning) waitingEvents.add(packet);
> 413 else processEvent(packet);
> 414 }
> 415 } else {
> 416 waitingEvents.add(packet);
> 417 }
> 418 }
> 419
> 420 public void queueEventOfDeath() {
> 421 waitingEvents.add(eventOfDeath);
> 422 }
> 423
> 424 @Override
> 425 public void run() {
> 426 try {
> 427 isRunning = true;
> 428 while (true) {
> 429 Object event = waitingEvents.take();
> 430 if (event == eventOfDeath) {
> 431 wasKilled = true;
> 432 } else {
> 433 processEvent(event);
> 434 }
> 435 if (wasKilled)
> 436 synchronized (waitingEvents) {
> 437 if (waitingEvents.isEmpty()) {
> 438 isRunning = false;
> 439 break;
> 440 }
> 441 }
> 442 }
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