Hi David,
Solaris problems aside, overall it looks fine. Some minor things I noted:
I noticed that exitCode is never modified in agentA() or agentB(), so
there isn't much point to having it. If you reach the bottom of the
function, it passed, so PASSED can be returned. The code would be more
clear if it did this. As-is it is implied that you can reach the bottom
when it fails.
Is detaching the threads along the failure paths really needed? exit()
is called, so this would seem to make it unnecessary.
I prefer assignments not to be embedded inside the "if" condition. The
DetachCurrentThread code in THREAD_return() is much more readable than
the similar code in agentA() and agentB().
In the test:
54 // Generally as long as we don't crash of throw unexpected
55 // exceptions then the test passes. In some cases we know
exactly
"of" should be "or".
Shouldn't you be catching exceptions for all the Thread methods you are
calling? Otherwise the test will exit if one is thrown, and the above
comment indicates that you don't want this.
Don't we normally put these tests in a package?
thanks,
Chris
On 7/5/18 2:58 AM, David Holmes wrote:
<sigh> Solaris compiler complains about doing a return from inside a
do-while loop. I'll have to rework part of the fix tomorrow.
David
On 5/07/2018 6:19 PM, David Holmes wrote:
Bug: https://bugs.openjdk.java.net/browse/JDK-8205878
Webrev: http://cr.openjdk.java.net/~dholmes/8205878/webrev/
Problem:
The tests create native threads that attach to the VM through
JNI_AttachCurrentThread but which then terminate without detaching
themselves. When the VM exits and we're using Flight Recorder
"dumponexit" this leads to a call to VM_PrintThreads that in part
wants to print the per-thread CPU usage. When we encounter the
threads that have terminated already the low level
pthread_getcpuclockid calls returns ESRCH but the code doesn't expect
that and so fails an assert in debug mode and can SEGV in product mode.
Solution:
Serviceability-side: fix the tests
Change the tests so that the threads detach before terminating. The
two tests are (surprisingly) written in completely different styles,
so the solution also takes on two different styles.
Runtime-side: make the VM more robust in the fact of JNI attached
threads that terminate before detaching, and add a regression test
I took a good look at the low-level code for interacting with
arbitrary threads and as far as I can see the problem only exists for
this one case of pthread_getcpuclockid on Linux. Elsewhere the
potential for a library call failure just reports an error value
(such as -1 for the cpu time used).
So the fix is simply to allow for ESRCH when calling
pthread_getcpuclockid and return -1 for the cpu usage in that case.
I created a new regression test to create a new native thread, attach
it and then let it terminate while still attached. The java code then
calls various Thread and ThreadMXBean functions on it to ensure there
are no crashes or unexpected exceptions.
Testing:
- old tests with fixed run-time
- old run-time with fixed tests
- mach tier4 (which exposed the problem - that's where we enable
Flight recorder for the tests) [in progress]
- mach5 tier 1-3 for good measure [in progress]
- new regression test
Thanks,
David
