1u0 commented on a change in pull request #9383: [FLINK-13248] [runtime] Adding
processing of downstream messages in AsyncWaitOperator's wait loops
URL: https://github.com/apache/flink/pull/9383#discussion_r315124537
##########
File path:
flink-streaming-java/src/main/java/org/apache/flink/streaming/api/operators/async/Emitter.java
##########
@@ -97,22 +102,18 @@ public void run() {
}
}
- private void output(AsyncResult asyncResult) throws
InterruptedException {
+ /**
+ * Executed as a mail in the mailbox thread. Output needs to be guarded
with checkpoint lock (for the time being).
+ *
+ * @param asyncResult the result to output.
+ */
+ private void output(AsyncResult asyncResult) {
if (asyncResult.isWatermark()) {
- synchronized (checkpointLock) {
- AsyncWatermarkResult asyncWatermarkResult =
asyncResult.asWatermark();
+ AsyncWatermarkResult asyncWatermarkResult =
asyncResult.asWatermark();
Review comment:
This action can be executed by a normal mailbox loop (not the one running in
`AsyncWaitOperator` via `yieldToDownstream()`), that doesn't run letters under
checkpoint lock (yet).
Also, I think you are losing guarantee, that this operation and
`streamElementQueue.poll()` happen atomically.
It may happen, that task checkpoint, then restart and restore would emit
duplicate events.
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