jiajunwang commented on a change in pull request #1000:
URL: https://github.com/apache/helix/pull/1000#discussion_r435452708
##########
File path:
helix-core/src/main/java/org/apache/helix/manager/zk/CallbackHandler.java
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@@ -200,6 +208,37 @@ protected void handleEvent(NotificationContext event) {
logger.warn("Exception in callback processing thread. Skipping
callback", e);
}
}
+
+ public boolean queueIsEmpty() {
+ return _eventQueue.isEmpty();
+ }
+ }
+
+ class RefreshTask implements Runnable {
+ @Override
+ public void run() {
+ try {
+ while (true) {
+ long currentTime = System.currentTimeMillis();
+ long remainingTime = _lastEventTime +
_periodicRefreshTriggerInterval - currentTime;
+ if (remainingTime <= 0) {
+ // If there is no event in the queue, meaning this long idle time
could be due to lack of events
+ // Otherwise, if there is event in the queue, this long idle time
is due to slow process of events
+ if (_batchCallbackProcessor == null ||
_batchCallbackProcessor.queueIsEmpty()) {
+ NotificationContext changeContext = new
NotificationContext(_manager);
+ changeContext.setType(Type.CALLBACK);
+ changeContext.setChangeType(_changeType);
+ enqueueTask(changeContext);
Review comment:
The problem of parallelism here is not 2 threads try to run at the same
time. As you mentioned it is protected by synchronization.
The concern is out of order. I mentioned this scenario during the
discussion. But I guess the argument that it won't make it worse since we are
basically doing a similar batch mode processing here.
Meaning, whatever potential issues that we saw in the batch mode may appear
in this refresh.
Let's put this concern aside. Since if any problem, we will need to fix it
for the batch mode anyway.
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