java.lang.Thread.contextClassLoader : what if it were a weak reference ?
Thomas.Hawtin at Sun.COM
Mon Mar 23 04:11:39 PDT 2009
Sylvain Laurent wrote:
> I'm tracking classloader leaks more or less as a hobby and found out
> that one of the (many) source of leaks come from threads that still have
> a reference to a classloader through their contextClassLoader instance
> So, I'm wondering : what if instead of
> "private ClassLoader contextClassLoader;" we had "private
> WeakReference<ClassLoader> contextClassLoaderRef" and the method
> getContextClassLoader would more or less
> returned contextClassLoaderRef.get() ?
> Would it break many things ? is it incompatible with the specs ?
How much it would break, I wouldn't like to guess.
Incompatible? Yes. It is legitimate to use a class loader only through
As for solutions: I guess containers could add a fake context class
loader with a weak reference to the real one (perhaps parent could
optionally become a weak reference?). Really there needs to be more care
taken when creating threads to make sure the context class loader (and
indeed InheritableThreadLocals) are inherited only when appropriate.
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