Jeroen Frijters wrote:
Ian Rogers wrote:
here is the revised patch.
+ int arraySize = group.activeCount();
+ Thread[] threadList = new Thread[arraySize];
+ int filled = group.enumerate(threadList);
+ while (filled == arraySize)
+ {
+ arraySize *= 2;
+ threadList = new Thread[arraySize];
+ filled = group.enumerate(threadList);
+ }
Shouldn't the initial array be arraySize + 1, to avoid always having to
enumerate twice?
This code is taken from Thread.getAllStackTraces so the problem should
effect both.
A bigger problem is that the ThreadLocal can be resurrected after the finalizer
has run, so you need to either make localIndex in ThreadLocal volatile and set
it to -1 in the finalizer, or use a PhantomReference and a ReferenceQueue to do
the clean up.
How can then the thread local be resurrected after the finalizer is run?
All the references in ThreadLocal and InheritableThreadLocal are weak
and will be atomically cleared prior to the finalizer being run. All
other references must be dead for the finalizer to have been run. The
finalizer doesn't use the ThreadLocal it just clears all references to
the slot it used to reference prior to saying that slot can be reused.
Given that thread locals normally only die when the VM shuts down or by
class unloading, its quite tempting just to ignore the situation of
reclaiming their storage - its certainly a much smaller problem than the
performance of get and set.
Thanks,
Ian
