[jira] [Commented] (WICKET-6944) Memory leak in WicketEndpoint

["Thomas Heigl (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/WICKET-6944?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17472208#comment-17472208 ] 

Thomas Heigl commented on WICKET-6944:
--------------------------------------

[~mgrigorov]: Do you have any idea how to best solve this?

I think we should keep the listener in a field and remove it when the connection is closed.

> Memory leak in WicketEndpoint
> -----------------------------
>
>                 Key: WICKET-6944
>                 URL: https://issues.apache.org/jira/browse/WICKET-6944
>             Project: Wicket
>          Issue Type: Bug
>          Components: wicket-native-websocket
>    Affects Versions: 9.7.0
>            Reporter: Thomas Heigl
>            Assignee: Thomas Heigl
>            Priority: Major
>         Attachments: image-2022-01-10-18-52-42-193.png
>
>
> Our application OOMed yesterday after about 2-3 weeks of continuous uptime. We normally deploy every other day, so we never noticed this issue before.
> The heap dump identified the possible culprit as {{{}WicketEndpoint$ApplicationListener{}}}:
> !image-2022-01-10-18-52-42-193.png!
> Every new websocket connection registers a new instance of this application listener and after a while we ended up with millions of these listeners:
> {code:java}
> @Override
> public void onOpen(Session session, EndpointConfig endpointConfig)
> {
>     String appName = getApplicationName(session);
>     WebApplication app = (WebApplication) WebApplication.get(appName);
>     app.getApplicationListeners().add(new ApplicationListener(applicationDestroyed));
>     try
>     {
>         ThreadContext.setApplication(app);
>         javaxWebSocketProcessor = new JavaxWebSocketProcessor(session, app, endpointConfig);
>     }
>     finally
>     {
>         ThreadContext.detach();
>     }
> }
> {code}
> Instead of creating a new listener for every connection, the listener should be a singleton.



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