On 05/07/2013 03:26 PM, Thomas Schatzl wrote:
Hi,
On Tue, 2013-05-07 at 15:12 +0200, Peter Levart wrote:
On 05/07/2013 09:51 AM, Thomas Schatzl wrote:
Hi all,
On Tue, 2013-05-07 at 12:31 +1000, David Holmes wrote:
Catching ThreadDeath is futile. If someone is invoking stop() then you
can encounter the ThreadDeath anywhere and it is impossible to write
completely robust code in the face of such an async exception. So please
let's not even go there. stop() is long deprecated and should never be used.
Backing up I think the try/catch(IE|OOME) around wait() is the most
reasonable solution here. Anyone messing with instrumentation or
overriding etc can break things - so be it - don't do that.
StackOverflowError can also completely break many things - again it is
effectively an async exception and writing async-exception-safe Java
code is impractical if not impossible.
I can understand this reasoning.
I provided a new patch (this time for review)
http://cr.openjdk.java.net/~tschatzl/7038914/webrev.1/ which implements
this change as suggested.
Regarding regression testing, I marked this bug as "noreg-other" with
the explanation that it is too hard to write a proper regression test,
and the note that any test would involve using methods that we don't
give any guarantees for (overriding package private jdk methods,
instrumentation).
Hi Thomas,
Does the bug reproducer I sent to the list not work for you? The test
can check the return value of refQueue.poll() and decide if it passes or
not (null return means the ReferenceHandler thread has died and the bug
is here, non-null return means thread still works and there is no bug).
I will check the code again, but unfortunately I think it does not help
a lot.
The problem of reproducing this issue is trying to get the
ReferenceHandler to die, i.e. have the OOME occur in the reference
handler thread.
The allocation of the InterruptedException is such a small allocation so
that in almost all of the cases of OOME, its allocation still succeeds
or is not the actual cause for the OOME. So the probability that the
java application threads get the OOME to handle is much higher,
especially in the stress tests.
There is a message emitted by the VM reading "java.lang.OutOfMemoryError
thrown from the UncaughtExceptionHandler in thread "Reference Handler""
that is sufficient to detect the problem itself (at least if you enable
some flags).
I will look at it again and report back if it can be used in some way.
On my computer the test always produced the same result. So it's pretty
reliable. The trick is in fillHeap() method that fills the heap so that
even "new Object[1]" throws OOME. Throwable object takes at least the
same space as Object[1];
Regards, Peter
Thanks,
Thomas
