[GitHub] [pulsar] 315157973 commented on pull request #11183: Fix the dead lock when using hasMessageAvailableAsync and readNextAsync

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

315157973 commented on pull request #11183:
URL: https://github.com/apache/pulsar/pull/11183#issuecomment-872699118


   Great work! This is very difficult to troubleshoot, thanks penghui
   When the Future has been completed, use future.whenComplete at this time, and the current thread will be used. A thread switch causes a deadlock. Here is a Demo:
   ```
           CompletableFuture<Void> future = new CompletableFuture<>();
           ScheduledExecutorService executorService = new ScheduledThreadPoolExecutor(1,
                   new BasicThreadFactory.Builder().namingPattern("metrics-schedule-pool-%d").build());
           executorService.execute(() -> {
               System.out.println("executorService:" + Thread.currentThread().getName());
               future.complete(null);
           });
           Thread.sleep(5000);
   
           future.whenComplete(((unused, throwable) -> {
               System.out.println("whenComplete:" + Thread.currentThread().getName());
           }));
           System.out.println("out:" + Thread.currentThread().getName());
   ```
   
   ![image](https://user-images.githubusercontent.com/9758905/124219362-d1d04d00-db2e-11eb-8fde-cb25641bd261.png)
   


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