mgao0 commented on a change in pull request #1002:
URL: https://github.com/apache/helix/pull/1002#discussion_r424721525
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File path:
helix-core/src/main/java/org/apache/helix/messaging/handling/HelixTaskExecutor.java
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@@ -524,12 +527,27 @@ public void finishTask(MessageTask task) {
private void updateMessageState(List<Message> readMsgs, HelixDataAccessor
accessor,
String instanceName) {
Builder keyBuilder = accessor.keyBuilder();
- List<PropertyKey> readMsgKeys = new ArrayList<>();
+ List<String> readMsgPaths = new ArrayList<>();
+ List<DataUpdater<ZNRecord>> updaters = new ArrayList<>();
for (Message msg : readMsgs) {
- readMsgKeys.add(msg.getKey(keyBuilder, instanceName));
+ readMsgPaths.add(msg.getKey(keyBuilder, instanceName).getPath());
_knownMessageIds.add(msg.getId());
+ /**
+ * We use the updater to avoid race condition between writing message to
zk as READ state and removing message after ST is done
+ * If there is no message at this path, meaning the message is removed
so we do not write the message
+ */
+ updaters.add(new DataUpdater<ZNRecord>() {
+ @Override
+ public ZNRecord update(ZNRecord currentData) {
+ if (currentData == null) {
+ LOG.warn("Message {} targets at {} has already been removed before
it is set as READ on instance {}", msg.getId(), msg.getTgtName(), instanceName);
Review comment:
@jiajunwang I have added the logging. Can you please check if the
message is good?
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