Hi Jc,
Thank you for reviewing this change. I had the similar concerns initially
regarding the losing coverage in the general case and was thinking about
detecting the Graal frames and adjusting the effective stack depth to not count
them. However, I found this approach a quite cumbersome and finally decided to
not follow it. In the approach you suggested my concern is that even for
consequent calls of GetFrameCount(), as I understand, there is no guarantee
that there are no Graal frames on the stack and it would result in the test
failure.
Best regards,
Daniil
From: JC Beyler <jcbey...@google.com>
Date: Friday, August 24, 2018 at 4:49 PM
To: <daniil.x.ti...@oracle.com>
Cc: <serviceability-dev@openjdk.java.net>
Subject: Re: RFR: 8209585: [Graal] vmTestbase/nsk/jvmti/scenarios/sampling
tests fail with "Too small stack of resumed thread"
Hi Daniil,
Just my two cents about this :)
I was looking at this and wondered if it made sense to fix the test this way (I
always worry about simplifying a test and losing coverage). I understand the
bug is that it is possible that between both calls, Graal could add some frames
and therefore might trip this test:
- if (frameStackSize < frameCount) {
However, by removing the test altogether and only relying on the suspended
frames, are we not reducing our coverage of the test (basically never really
testing the running threads anymore, only the suspended ones?).
Alternatively, when we look at this code and the hypothesis of Graal stacks
"slipping in between calls", two cases could occur:
A) The Graal frames are present in the first call but not the second
B) The Graal frames are present in the second call but not the first
In the (B) case, the test would not trip, as frameStackSize would be >=
frameCount so that is not an issue.
In the (A) case, we could simply recall the frameCount and assure ourselves the
frames have disappeared, no?
Something like:
if (frameStackSize < frameCount) {
// This can occur for Graal if graal frames crept in. Call
getFrameCount again and see if they have disappeared since
// frameStackSize seems to say so.
... insert call here and a new check...
NSK_COMPLAIN5("Too small stack of %s thread #%d (%s):\n"
"# getStackTrace(): %d\n"
"# getFrameCount(): %d\n",
kind, i, threadsDesc[i].threadName,
(int)frameStackSize, (int)frameCount);
nsk_jvmti_setFailStatus();
}
Just my 2 cents because I worry about simplifying a test for Graal but losing
coverage in the general case,
Jc
On Thu, Aug 23, 2018 at 8:29 PM Daniil Titov <daniil.x.ti...@oracle.com> wrote:
Please review the change that fixes 4 JVMTI tests when running with Graal.
One of the checks these tests perform compares the number of frames in the
thread's stack returned by JVMTI GetFrameCount() with the number of frames
entries returned by JVMTI GetStackTrace(). The thread to be tested executes
arithmetic operations in the loop so the consequent calls of GetFrameCount()
or/and GetStackTrace() should return the stack trace of the same depth.
However, with Graal on, additional "adjustCompilationLevel" frames could
appear on the stack trace, e.g.:
adjustCompilationLevel:166, HotSpotGraalCompilerFactory
(org.graalvm.compiler.hotspot)
adjustCompilationLevel:504, HotSpotJVMCIRuntime (jdk.vm.ci.hotspot)
testedMethod:56, Test$Runner
run:67, Test$Runner
that results in the stack depth reported by the first invocation of
GetFrameCount() or GetStackTrace() might differ from the stack depth reported
by the consequent calls of the same methods.
The fix modifies the tests to ensure the check that GetFrameCount () and
GetStackTrace() report the same stack depth is performed only if the thread is
suspended. For two tests
(vmTestbase/nsk/jvmti/scenarios/sampling/SP02/sp02t001/TestDescription.java
and vmTestbase/nsk/jvmti/scenarios/sampling/SP06/sp06t001/TestDescription.java)
such check for suspended threads already exists so in these tests the
problematic check was not modified by just removed.
Issue: https://bugs.openjdk.java.net/browse/JDK-8209585
Webrev: http://cr.openjdk.java.net/~dtitov/8209585/webrev.01
Thanks,
Daniil
--
Thanks,
Jc
