[Bug classpath/27598] WeakHashMap can fail with concurrent readers

[Hans dot Boehm at hp dot com]

------- Comment #3 from Hans dot Boehm at hp dot com  2006-10-30 22:16 -------
I strongly disagree with closing this.  This is a threading bug.  It's nasty
precisely because it is not systematically reproducible.  That's no reason to
close it.

The problem is obviously still there.  Various readers call cleanQueue, which
calls internalRemove, which updates the data structure all without
synchronization.

The test case may have failed to catch it either because it doesn't do a good
job of testing for the kind of corruption that may occur here (lost deletions,
size decrements), or because it was run on two few processors to make the
failure likely, or because a failure in a hash table this large is probably
unlikely anyway.  A test case that actually reproduces an obscure threading bug
like this is valuable; in my opinion, the fact that a test case doesn't fail
doesn't mean much in cases like this.

It makes sense to close unreporducible bugs only if we can't track them down as
a result.  We already understand the problem here.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27598