In JaveScriptCore/wtf/FastMalloc.cpp, a scavengerThread is created, but never destroyed.
What is the bug you are reporting. This is expected behavior.
WebKit is not designed to be unloaded from a running applications, there are lots of reasons why this doesn't work.
Please feel free to reopen if I misunderstood your report, and there is a bug to be fixed.
I'm sure for most cases this is not a problem at all, but on the platform I am porting to, the pthread implementation will not exit until all threads have been destroyed.
It seems like it would be pretty easy to add a way to shut down the scavenger thread, is there a reason not to do this?