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Posted to commits@rocketmq.apache.org by GitBox <gi...@apache.org> on 2022/10/22 09:19:26 UTC
[GitHub] [rocketmq] codersfarm opened a new issue, #5380: countDownLatch.await in necessary in queryMessage
codersfarm opened a new issue, #5380:
URL: https://github.com/apache/rocketmq/issues/5380
In MQAdminImpl.class, queryMessage method, `CountDownLatch countDownLatch = new CountDownLatch(brokerAddrs.size());` the size is brokerAddrs.size(), and countDownLatch countDown finally. why need this method below `boolean ok = countDownLatch.await(timeoutMillis * 4, TimeUnit.MILLISECONDS);`
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[GitHub] [rocketmq] nowinkeyy commented on issue #5380: countDownLatch.await in necessary in queryMessage
Posted by GitBox <gi...@apache.org>.
nowinkeyy commented on issue #5380:
URL: https://github.com/apache/rocketmq/issues/5380#issuecomment-1287695804
The ```finally{}``` will executes whether or not it catches the exception, the method ```boolean ok = countDownLatch.await(timeoutMillis * 4, TimeUnit.MILLISECONDS);``` just used to block thread until countdownLatch goes to zero. If some broker failed, the countdownLatch cann't return to zero, the method ```await()``` will time out and the thread will log.warn.
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[GitHub] [rocketmq] codersfarm commented on issue #5380: countDownLatch.await in necessary in queryMessage
Posted by GitBox <gi...@apache.org>.
codersfarm commented on issue #5380:
URL: https://github.com/apache/rocketmq/issues/5380#issuecomment-1288281664
Thanks. Main thead is blocked by countDownLatch until sub thead complete. The countDownLatch will goes zero, countDownLatch.await(timeoutMillis * 4, TimeUnit.MILLISECONDS) execute immediately. The query this.mQClientFactory.getMQClientAPIImpl().queryMessage(addr, requestHeader, timeoutMillis * 3 is timeoutMillis * 3,and the countDownLatch.await is timeoutMillis * 4.
2022-10-24_090335
2022-10-24_090408
> Hi @codersfarm , IMO, I think the countDownLatch will goes zero whether the broker failed or not. And i think the purpose of this `await()` method is to wait for the for loop to complete so that the `queryResultList` results of querying all brokers can be retrieved. The `queryResultList` is incomplete without the `await()` method waiting for the completion of the for loop.
>
>  
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[GitHub] [rocketmq] nowinkeyy commented on issue #5380: countDownLatch.await in necessary in queryMessage
Posted by GitBox <gi...@apache.org>.
nowinkeyy commented on issue #5380:
URL: https://github.com/apache/rocketmq/issues/5380#issuecomment-1287988182
Hi @codersfarm ,
IMO, I think the countDownLatch will goes zero whether the broker failed or not. And i think the purpose of this ```await()``` method is to wait for the for loop to complete so that the ```queryResultList``` results of querying all brokers can be retrieved.
The ```queryResultList``` is incomplete without the ```await()``` method waiting for the completion of the for loop.
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[GitHub] [rocketmq] codersfarm commented on issue #5380: countDownLatch.await in necessary in queryMessage
Posted by GitBox <gi...@apache.org>.
codersfarm commented on issue #5380:
URL: https://github.com/apache/rocketmq/issues/5380#issuecomment-1288280929
Thanks. Main thead is blocked by countDownLatch until sub thead complete. The countDownLatch will goes zero, `countDownLatch.await(timeoutMillis * 4, TimeUnit.MILLISECONDS)` execute immediately. The query `this.mQClientFactory.getMQClientAPIImpl().queryMessage(addr, requestHeader, timeoutMillis * 3` is `timeoutMillis * 3`,and the `countDownLatch.await` is `timeoutMillis * 4`.
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[GitHub] [rocketmq] codersfarm commented on issue #5380: countDownLatch.await in necessary in queryMessage
Posted by GitBox <gi...@apache.org>.
codersfarm commented on issue #5380:
URL: https://github.com/apache/rocketmq/issues/5380#issuecomment-1288095767
Thanks
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[GitHub] [rocketmq] codersfarm commented on issue #5380: countDownLatch.await in necessary in queryMessage
Posted by GitBox <gi...@apache.org>.
codersfarm commented on issue #5380:
URL: https://github.com/apache/rocketmq/issues/5380#issuecomment-1287971054
The countDownLatch‘s size equals brokerAddrs.size(), `finally{}` is in for loop(loop size equals brokerAddrs.size())，when for loop executes the countDownLatch goes zero whether the broker failed or not. Is this right?
- if true, the method `boolean ok = countDownLatch.await(timeoutMillis * 4, TimeUnit.MILLISECONDS);` maybe no use.
- if false, even if the broker failed and countDownLatch>=1, the method will execute 24 seconds. for users query message by eByUniqKey
> The `finally{}` will executes whether or not it catches the exception, the method `boolean ok = countDownLatch.await(timeoutMillis * 4, TimeUnit.MILLISECONDS);` just used to block thread until countdownLatch goes to zero. If some broker failed, the countdownLatch cann't return to zero, the method `await()` will time out and the thread will log.warn.
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[GitHub] [rocketmq] codersfarm closed issue #5380: countDownLatch.await in necessary in queryMessage
Posted by GitBox <gi...@apache.org>.
codersfarm closed issue #5380: countDownLatch.await in necessary in queryMessage
URL: https://github.com/apache/rocketmq/issues/5380
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