In JIRA we've noticed that crowd component that we use doesn't shutdown MultiThreadedHttpConnectionManager. This causes threads to hang after those components were disposed. In fact, crowd even introduce ShutdownIgnoringMultiThreadedHttpConnectionManager .

All instances of MultiThreadedHttpConnectionManager should be properly cleaned up and all ShutdownIgnoringMultiThreadedHttpConnectionManager usages should be replaced with MultiThreadedHttpConnectionManager (with proper cleanup).

Relying on MultiThreadedHttpConnectionManager#shutdownAll is really bad idea (and this method should not be used ever, as this causes deadlocks).

Problematic instances found by thread analysis in JIRA:

In the com.atlassian.crowd.manager.webhook.WebhookPinger.WebhookPinger()

public WebhookPinger()
{
    this(new HttpClient(new MultiThreadedHttpConnectionManager()));
}

In the com.atlassian.crowd.integration.rest.service.RestExecutor:

private final ShutdownIgnoringMultiThreadedHttpConnectionManager connectionManager = new ShutdownIgnoringMultiThreadedHttpConnectionManager();