CODEWITHSUNDEEP
javaweb-applicationsmemory-leaksheap-memoryjetty-9
Sonny
Sonny

Reputation: 2133

Jetty webapp continues to grow into heap space: (OutOfMemoryError Java heap space)

I have a memory leak in my Jetty webapp (9.3.6) (java.lang.OutOfMemoryError: Java heap space error).

A quick note for the moderators, this is NOT a PermGen problem which seems to have documented solutions. I tried a number of SO searches and this problem did not seem to be asked about in any of the related questions.

It is a websocket application, and I am profiling it with JVisualVM, and I see that there are a large number of Strings that get allocated that don't ever get removed, and I have no idea how or what to do with that problem. In addition, I see both org.eclipse.jetty.websocket.server.WebSocketServerFactory#1 and org.eclipse.jetty.webapp.WebAppClassLoader#1 grow steadily (rapidly?) in size. To fix that problem (or so I thought) I read the memory management page in Jetty here and added the AppContextLeakPreventer to my ${jetty.home}/etc/jetty.xml and that is not helping either (discovered that my redoing my heap dump).

What's the correct way to deal with constantly growing heap in a Jetty webapp? At the moment, I am pre-production and so I am not hot-deploying the server. I have also increased the heap size to -Xmx256M (it is a 1GB RAM AWS instance, so not much elbow room here).

My client applications are at the moment few in number, and I am primarily observing constantly growing memory profile using JVisualVM.

Any input is appreciated. Any pointers as to figuring out exactly what classes are causing this is also appreciated. I currently got the aforementioned information from the heap dump in the "Biggest objects" section of the summary/inspect tab.

(edit, 02/15)

I am adding some testing notes after realizing that this is likely a bug in Jetty 9.3.6 (see http://dev.eclipse.org/mhonarc/lists/jetty-users/msg06666.html). I'd like to add that my current testing environment for this profiling work is firing up Java client sessions in very quick succession using a shell script (i.e., not describing a production environment, but this is clearly an issue for production environments as well). There are only three shells, but they are firing a brand new client session into the websocket server every 5 or so seconds, continuously (but they close the connection before they do it over again).

Upvotes: 3

Views: 1968

Answers (1)

Sonny
Sonny

Reputation: 2133

I confirm that moving to Jetty 9.3.7 removed this issue; I believe the heap space issue I faced has to do with the bug (and the fix) described in here.

Specifically, there was a bug in Jetty 9.3.6 (and, presumably, Jetty 9.3.5 as well), that did not clean up JSR356 (client) Session objects correctly on the Jetty server, resulting in a memory leak for applications whose clients reconnect often (or there are too many of them).

Hope this helps someone.

Upvotes: 3

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