gabriellefu commented on code in PR #23184:
URL: https://github.com/apache/kafka/pull/23184#discussion_r3832966589
##########
streams/src/main/java/org/apache/kafka/streams/state/internals/StoreQueryUtils.java:
##########
@@ -128,29 +128,33 @@ public static <R> QueryResult<R> handleBasicQueries(
final QueryResult<R> result;
final QueryHandler<?> handler =
QUERY_HANDLER_MAP.get(query.getClass());
- synchronized (position) {
- if (handler == null) {
- result = QueryResult.forUnknownQueryType(query, store);
- } else if (context == null || !isPermitted(position,
positionBound, context.taskId().partition())) {
- result = QueryResult.notUpToBound(
- position,
- positionBound,
- context == null ? null : context.taskId().partition()
- );
- } else {
- result = ((QueryHandler<R>) handler).apply(
- query,
- positionBound,
- config,
- store
- );
- }
- if (config.isCollectExecutionInfo()) {
- result.addExecutionInfo(
- "Handled in " + store.getClass() + " in " +
(System.nanoTime() - start) + "ns"
- );
+ // Lock order must match the write paths (store monitor, then
position),
+ // otherwise concurrent put/query can deadlock (KAFKA-19629).
+ synchronized (store) {
Review Comment:
❯ in restore, I changed the lock order to put first, which get the order of
store then position, then we realease the two lock and only get the position
lock, in this case, there won't be a deadlock
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