Hi David,
There are not documented the relation between -XX:*OnOutOfMemoryError and
ResourceExhausted, but JVMTI spec says ResourceExhausted is sent when VM
resource are exhausted.
https://docs.oracle.com/en/java/javase/12/docs/specs/jvmti.html#ResourceExhausted
As you said, we should not do other things when OutOfMemoryError is occurred.
But I think it should be compliant when we will use Java related code in the
event handler. If we do with C/C++ only (e.g. call printf()), I think we can do
that.
If all codes should not be run when OutOfMemoryError is occurred,
ResourceExhausted should be obsoleted, or we need to add the note for JVMTI
document.
Thanks,
Yasumasa
On 2019/07/23 16:43, David Holmes wrote:
Hi Yasumasa,
On 23/07/2019 5:24 pm, Yasumasa Suenaga wrote:
Hi all,
I tried to use JVMTI agent which hooks ResourceExhausted event and
-XX:ExitOnOutOfMemoryError together.
The process was exited when OutOfMemoryError was occurred, but
ResourceExhausted event was not fired.
I checked HotSpot implementation, -XX:*OutOfMemoryError is processed before
JVMTI event processing.
http://hg.openjdk.java.net/jdk/jdk/file/d999a1a11485/src/hotspot/share/gc/shared/memAllocator.cpp#l125
IMHO ResourceExhausted should be called before -XX:*OutOfMemoryError.
If it is a bug, I will file it to JBS and fix it.
I don't think it is a bug. First, there's no specification for how these two
things interact - -XX:*OnOutOfMemoryError is just a VM specific
debugging/diagnostic hook. Second, if we're out of memory then we don't want to
be doing other things which may need to also acquire memory. Third, no matter
which way you code this someone may in some case want it the other way - and
it's not worth coding to allow such flexibility IMO.
Just my $2. :)
Cheers,
David
Thanks,
Yasumasa
