I set up a single tomcat to run Crowd and Confluence. Then I set up Confluence to authenticate in Crowd. Then I restarted the tomcat.

It happened that when tomcat starts, it tries to start Confluence context first. When Confluence context starts, it seems to be trying to authenticate in Crowd. But Crowd is not yet started, so Confluence initialization just hangs. All this is done in a single thread, so Crowd doesn't get a chance to start and the system hangs.

A workaround is to remove confluence context from tomcat, start normally, then add confluence context so it gets automatically deployed.