Memory and CPU issues about aw-watcher-jetbrains

[OlivierMary]

Hi there, it's same error than #4 ?

[jdwil]

@OlivierMary I didn't notice any exception like that, but I need to re-enable the plugin today for some work, so I'll keep an eye out and post again if I see it, or anything else that is new.

[jdwil]

I just saw this error, but I haven't had any more issues with memory or sluggishness.

java.util.ConcurrentModificationException
	at java.base/java.util.ArrayList$Itr.checkForComodification(Unknown Source)
	at java.base/java.util.ArrayList$Itr.next(Unknown Source)
	at fr.mary.olivier.aw.watcher.ReportActivity.sendAllEvents(ReportActivity.java:192)
	at fr.mary.olivier.aw.watcher.ReportActivity.lambda$addAndSendEvent$2(ReportActivity.java:180)
	at com.intellij.openapi.application.impl.ApplicationImpl$1.run(ApplicationImpl.java:311)
	at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source)
	at java.base/java.util.concurrent.FutureTask.run(Unknown Source)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
	at java.base/java.lang.Thread.run(Unknown Source)

[OlivierMary]

Any steps to reproduce it ? Nobody can tell me how to reproduce, I tried many stress test while using IDEA and never had this error..

[jdwil]

Sorry, but I can't seem to reliably reproduce any of the issues. Sometimes I use PyCharm and Webstorm at the same time. Is it possible that that is impacting it?

[Martomate]

While I don't know the cause of the CPU and memory usage, I do have an idea about why the exception is thrown. Here is a stripped down version of the important code:

public static void addAndSendEvent( ... ) {
    ApplicationManager.getApplication().executeOnPooledThread(() -> {
        Event event = new Event( ... );
        getEventsToSend().add(event);
        sendAllEvents();
    });
}

private static synchronized void sendAllEvents() {
    for (Event event : getEventsToSend()) {
        // send the event
    }
}

private static synchronized List<Event> getEventsToSend() {
    return eventsToSend;
}

Imagine the following scenario:

• Thread 1 enters addAndSendEvents.
• A new thread is born, call it thread 2. It adds an event to the list and starts running the for loop.
• Thread 1 goes on to do other things.
• After a while thread 1 runs addAndSendEvents again.
• A new thread is born, call it thread 3. It adds an event to the list, but since thread 1 is still running the for loop, thread 3 cannot enter sendAllEvents. It waits.
• Thread 1 tries to run the next iteration of the for loop, but the list is modified and the exception is thrown.

The fact that ´getEventsToSend´ is synchronized doesn't really do much.

The solution? You can synchronize on the list, like this:

synchronize (eventsToSend) {
    // do things on the list
}

// other code

synchronize (eventsToSend) {
    // do other things on the list
}

If a thread is running one of these clauses, the other clause cannot be run and has to wait.

Hope this helps.

Have a nice day!

[OlivierMary]

@Martomate thanks will look at this !

[OlivierMary]

I post a new version 1.0.8 tell me if problem is solved. You can DL it from release page on github or wait 2-3d on Jetbrains plugins

[Martomate]

It seems to be solved. I haven't seen the error since your fix :)

[OlivierMary]

Great ! I close it :)