RFR (11): 8205878: pthread_getcpuclockid is expected to return 0 code
david.holmes at oracle.com
Thu Jul 5 09:58:39 UTC 2018
<sigh> Solaris compiler complains about doing a return from inside a
do-while loop. I'll have to rework part of the fix tomorrow.
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/
> 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.
> 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.
> - 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
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