[SOLR-17305] SolrDispatchFilter CoreContainerProvider can hang on startup

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Duplicate
• Assignee: David Smiley
• Reporter: David Smiley
• Created: 21/May/24 19:00
• Updated: 29/May/24 23:51
• Resolved: 21/May/24 19:53

Description

I've been stumped a number of times over the years looking at an unreproducible test failure that shows SolrDispatchFilter.init calling CoreContainerProvider.waitForReadyService and waiting on a CoundDownLatch indefinitely. Meanwhile, no other trace or problems in the logs. Eventually the test will timeout and we see a thread dump.

I suspect a timing bug of exactly when GC happens interplaying with the use of WeakHashMap. In particular I see ContextInitializationKey's constructor publishing "this" to the ServletContext which seems like a bad place to put such logic (constructors publishing themselves is suspicious in general; avoid it). But the point is that it'll overwrite an existing entry in the context that may very well be there, thus suddenly making an existing entry in a WeakHashMap weakly reachable and it may be removed. There is too much complexity there; I think it should be overhauled a bit. I'm working on a PR.

Issue Links

• duplicates: SOLR-17118 Solr deadlock during servlet container start