RFR (11): 8205878: pthread_getcpuclockid is expected to return 0 code
serguei.spitsyn at oracle.com
serguei.spitsyn at oracle.com
Tue Jul 10 02:42:57 UTC 2018
On 7/9/18 19:35, David Holmes wrote:
> On 10/07/2018 12:07 PM, serguei.spitsyn at oracle.com wrote:
>> Hi David,
>>
>> It looks good modulo the minor comments that others have already found.
>
> Thanks for taking a look.
>
>> Could I ask you to fix a couple of really minor issues in new test?
>>
>> Unneeded spaces are at lines 84 and 51 in .java and .c files:
>>
>> 83 if (mbean.isThreadCpuTimeSupported() &&
>> 84 mbean.isThreadCpuTimeEnabled() ) {
>> . . .
>>
>> 51 class_id = (*env)->FindClass (env, "java/lang/Thread");
>
> Sorry Serguei, too late.
Not a problem, David.
Sorry for being late.
Thanks,
Serguei
> David
>
>> Thanks,
>> Serguei
>>
>>
>> On 7/9/18 15:17, David Holmes wrote:
>>> Thanks Chris!
>>>
>>> Can I please get a second review.
>>>
>>> David
>>>
>>> On 10/07/2018 7:50 AM, Chris Plummer wrote:
>>>> On 7/9/18 2:41 PM, David Holmes wrote:
>>>>> Hi Chris,
>>>>>
>>>>> On 10/07/2018 4:22 AM, Chris Plummer wrote:
>>>>>> Hi David,
>>>>>>
>>>>>> Would it be better to problem list this test on solaris using
>>>>>> JDK-8156708. That way when JDK-8156708 is fixed it can come off
>>>>>> the problem list and start executing on solaris.
>>>>>
>>>>> JDK-8156708 is already fixed - it's a dup of JDK-8154715. We could
>>>>> only fix this for VM created threads. The general problem of TLS
>>>>> destructors looping if a thread terminates without detaching from
>>>>> the VM is not solvable - other than by not using TLS in the VM.
>>>> Ok, I misunderstood your comments in the test.
>>>>
>>>> Changes look fine.
>>>>
>>>> Chris
>>>>>
>>>>> Thanks,
>>>>> David
>>>>>
>>>>>> thanks,
>>>>>>
>>>>>> Chris
>>>>>>
>>>>>> On 7/8/18 4:58 PM, David Holmes wrote:
>>>>>>> tl;dr skip the new regression test on Solaris
>>>>>>>
>>>>>>> New webrev:
>>>>>>>
>>>>>>> http://cr.openjdk.java.net/~dholmes/8205878/webrev.v3/
>>>>>>>
>>>>>>> This excludes the test from running on Solaris, so the makefile
>>>>>>> doesn't bother compiling this native test and the Java part of
>>>>>>> the test adds:
>>>>>>>
>>>>>>> ! * @requires os.family != "windows" & os.family != "solaris"
>>>>>>> * @summary Basic test of Thread and ThreadMXBean queries on a
>>>>>>> natively
>>>>>>> * attached thread that has failed to detach before
>>>>>>> terminating.
>>>>>>> + * @comment The native code only supports POSIX so no windows
>>>>>>> testing; also
>>>>>>> + * we have to skip solaris as a terminating thread
>>>>>>> that fails to
>>>>>>> + * detach will hit an infinite loop due to TLS
>>>>>>> destructor issues - see
>>>>>>> + * comments in JDK-8156708
>>>>>>>
>>>>>>> Note this means that Solaris is not affected by the original
>>>>>>> issue because a still-attached native thread can't actually
>>>>>>> terminate due to the TLS destructor infinite-loop issue.
>>>>>>>
>>>>>>> Thanks,
>>>>>>> David
>>>>>>>
>>>>>>> On 6/07/2018 6:07 PM, David Holmes wrote:
>>>>>>>> <sigh> The new test is hanging on Solaris. I just discovered we
>>>>>>>> don't run these tests on Solaris until tier4.
>>>>>>>>
>>>>>>>> David
>>>>>>>>
>>>>>>>> On 6/07/2018 8:40 AM, David Holmes wrote:
>>>>>>>>> Hi Chris,
>>>>>>>>>
>>>>>>>>> Thanks for looking at this.
>>>>>>>>>
>>>>>>>>> Updated webrev:
>>>>>>>>>
>>>>>>>>> http://cr.openjdk.java.net/~dholmes/8205878/webrev.v2/
>>>>>>>>>
>>>>>>>>> Only real changes in ji05t001.c. (And fixed typo in the new test)
>>>>>>>>>
>>>>>>>>> More below ...
>>>>>>>>>
>>>>>>>>> On 6/07/2018 7:55 AM, Chris Plummer wrote:
>>>>>>>>>> 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.
>>>>>>>>>
>>>>>>>>> I resisted any and all urges to do any kind of unrelated code
>>>>>>>>> cleanup in the tests - once you start you may end up doing a
>>>>>>>>> full rewrite.
>>>>>>>>>
>>>>>>>>>> Is detaching the threads along the failure paths really
>>>>>>>>>> needed? exit() is called, so this would seem to make it
>>>>>>>>>> unnecessary.
>>>>>>>>>
>>>>>>>>> You're right that isn't necessary. I'll remove the changes
>>>>>>>>> from before the exits in ji05t001.c
>>>>>>>>>
>>>>>>>>>> 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().
>>>>>>>>>
>>>>>>>>> It's an existing style already used in that test e.g.
>>>>>>>>>
>>>>>>>>> 287 if ((res =
>>>>>>>>> 288 JNI_ENV_PTR(vm)->AttachCurrentThread(
>>>>>>>>> 289 JNI_ENV_ARG(vm, (void **) &env), (void
>>>>>>>>> *) 0)) != 0) {
>>>>>>>>>
>>>>>>>>> and I don't mind it, so I'd prefer not to change it.
>>>>>>>>>
>>>>>>>>>> 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".
>>>>>>>>>
>>>>>>>>> Well spotted. Thanks.
>>>>>>>>>
>>>>>>>>>> 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.
>>>>>>>>>
>>>>>>>>> I'm not expecting there to be any exceptions from any of the
>>>>>>>>> called methods. That would potentially indicate a problem in
>>>>>>>>> handling the terminated native thread, so would indicate a
>>>>>>>>> test failure.
>>>>>>>>>
>>>>>>>>>> Don't we normally put these tests in a package?
>>>>>>>>>
>>>>>>>>> Doesn't seem to be any hard and fast rule. I only uses
>>>>>>>>> packages when they are important for the test. In runtime we
>>>>>>>>> have 905 java files and only 116 have a package statement. It
>>>>>>>>> varies elsewhere.
>>>>>>>>>
>>>>>>>>> Thanks,
>>>>>>>>> David
>>>>>>>>>
>>>>>>>>>> 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
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>
>>>>>>
>>>>
>>>>
>>
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