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https://issues.apache.org/jira/browse/FLINK-8876?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16389793#comment-16389793
]
ASF GitHub Bot commented on FLINK-8876:
---------------------------------------
Github user StephanEwen commented on a diff in the pull request:
https://github.com/apache/flink/pull/5645#discussion_r172911926
--- Diff:
flink-formats/flink-avro/src/main/java/org/apache/flink/formats/avro/typeutils/AvroSerializer.java
---
@@ -163,8 +224,19 @@ public T copy(T from, T reuse) {
@Override
public void copy(DataInputView source, DataOutputView target) throws
IOException {
- T value = deserialize(source);
- serialize(value, target);
+ if (CONCURRENT_ACCESS_CHECK) {
+ enterExclusiveThread();
+ }
+
+ try {
+ T value = deserialize(source);
--- End diff --
An alternative would be to do the following, but I would honestly not do
that. This is a heuristic anyways (otherwise we would need to use CAS on the
`currentThread` field).
```java
private void enterExclusiveThread() {
Thread previous = currentThread;
Thread thisThread = Thread.currentThread();
if (previous == null) {
reEntranceDepth = 1;
currentThread = thisThread;
}
else if (previous == thisThread) {
reEntranceDepth++;
}
else {
throw new IllegalStateException(
"Concurrent access to KryoSerializer. Thread 1:
" + thisThread.getName() +
" , Thread 2: " +
previous.getName());
}
}
private void exitExclusiveThread() {
if (--reEntranceDepth == 0) {
currentThread = null;
}
}
```
> Improve concurrent access handling in stateful serializers
> ----------------------------------------------------------
>
> Key: FLINK-8876
> URL: https://issues.apache.org/jira/browse/FLINK-8876
> Project: Flink
> Issue Type: Improvement
> Components: Core
> Reporter: Stephan Ewen
> Assignee: Stephan Ewen
> Priority: Major
> Fix For: 1.5.0, 1.6.0
>
>
> Some stateful serializers produce incorrect results when accidentally
> accessed by multiple threads concurrently.
> To better catch these cases, I suggest to add concurrency checks that are
> active only when debug logging is enabled, and during test runs.
> This is inspired by Kryo's checks for concurrent access.
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