315157973 commented on a change in pull request #8207:
URL: https://github.com/apache/pulsar/pull/8207#discussion_r500909339
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File path:
pulsar-client/src/main/java/org/apache/pulsar/client/impl/ConsumerBase.java
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@@ -677,19 +677,16 @@ protected void notifyPendingBatchReceivedCallBack() {
if (opBatchReceive == null || opBatchReceive.future == null) {
return;
}
- notifyPendingBatchReceivedCallBack(opBatchReceive);
+ synchronized (incomingMessages) {
Review comment:
> can you please explain the reason for this 'synchronized' block ?
The `notifyPendingBatchReceivedCallBack(OpBatchReceive<T> opBatchReceive)`
called in `notifyPendingBatchReceivedCallBack()` is not thread-safe, so locking
is necessary.
But not every call to `notifyPendingBatchReceivedCallBack()` needs to be
locked, only when there is an opBatchReceive that meets the conditions.
The scenarios where thread is not safe are as follows:
Thread A calls incomingMessages.peek(), finds that message A meets the
conditions, can join the Messages collection, and is preparing to poll. At this
time, thread B polls the message A first. The message polled by thread A is
actually message B, but message B does not meet the conditions for joining the
Messages set of thread A.
Look forward to your advice.
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