jon-wei commented on a change in pull request #6724: Fix issue that tasks
failed because of no sink for identifier
URL: https://github.com/apache/incubator-druid/pull/6724#discussion_r244906073
##########
File path:
server/src/main/java/org/apache/druid/segment/realtime/appenderator/AppenderatorImpl.java
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@@ -485,8 +486,12 @@ public void clear() throws InterruptedException
final List<Pair<FireHydrant, SegmentIdentifier>> indexesToPersist = new
ArrayList<>();
int numPersistedRows = 0;
long bytesPersisted = 0L;
- for (SegmentIdentifier identifier : sinks.keySet()) {
- final Sink sink = sinks.get(identifier);
+ Iterator<Map.Entry<SegmentIdentifier, Sink>> iterator =
sinks.entrySet().iterator();
+
+ while (iterator.hasNext()) {
Review comment:
@QiuMM
> I have never observed any exceptions caused by this. And I think there is
no need to worry about it because the program will wait for any outstanding
pushes to finish, then abandon the segment inside the persist thread:
I believe you're right that `push` is okay.
In the `persistAll` case I'm guessing what's happening is something like:
1. Task does an incremental publish for some sequence
2. Publish completes, `driver.registerHandoff` adds a callback after handoff
finishes that calls `appenderator.drop` -> `abandonSegment`
3. Task does another incremental publish for another sequence
4. Task calls `persistAll` which iterates through all Sinks, but during this
iteration, the handoff callback from the previous incremental publish finishes
and removes a Sink
For `push`, the input Sinks are read from the Sequence->Segments map instead
of looking at the entire set of Sinks, and `StreamAppenderatorDriver.publish`
removes the sequence's segments after the publish, so on the next incremental
publish, it doesn't have the same problem of accessing Sinks that were
handled/dropped as part of the previous incremental publish
Does that sound correct given what you're seeing?
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