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8349192: jvmti/scenarios/contention/TC05/tc05t001 fails: ERROR: tc05t001.cpp, 281: (waitedThreadCpuTime - waitThreadCpuTime) < (EXPECTED_ACCURACY * 1000000) #28206

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8349192: jvmti/scenarios/contention/TC05/tc05t001 fails: ERROR: tc05t001.cpp, 281: (waitedThreadCpuTime - waitThreadCpuTime) < (EXPECTED_ACCURACY * 1000000) #28206

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8349192: Test jvmti/scenarios/contention/TC05/tc05t001 fails: ERROR: …
sspitsyn Nov 8, 2025
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review: restore original EXPECTED_ACCURACY for Windows
sspitsyn Nov 9, 2025
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sspitsyn Nov 13, 2025
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2 changes: 1 addition & 1 deletion test/hotspot/jtreg/vmTestbase/nsk/jvmti/scenarios/contention/TC05/tc05t001/tc05t001.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -42,7 +42,7 @@ static const jlong EXPECTED_TIMEOUT_ACCURACY_NS = 300000;
#if (defined(WIN32) || defined(_WIN32))
static const jlong EXPECTED_ACCURACY = 16; // 16ms is longest clock update interval
#else
static const jlong EXPECTED_ACCURACY = 10; // high frequency clock updates expected
static const jlong EXPECTED_ACCURACY = 32; // high frequency clock updates expected
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@plummercj plummercj Nov 12, 2025

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The comments are somewhat misleading now. We choose 16 on WIN32 because that is the smallest interval allowed. We expect better clock refinement on other platforms and therefore better accuracy. Thus 10ms was chosen. Now we have one test case that was just over 16ms. Is there a reason to believe that couldn't happen with WIN32 also. If not, then the comments should reflect that.

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@sspitsyn sspitsyn Nov 12, 2025 •
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I feel that all these checks are just a source of this test instability. :)
I'm not sure I fully understand why those are needed and what was the original design. It is always possible to have some delays in waiting time, so the original assumptions about expected accuracy are not fully correct as they are a little bit overly strong.
From this point of view, I do not see why the comments are confusing. The EXPECTED_ACCURACY values are just based on the high frequency clock updates interval but should not be equal to it.
Would you like me to change the comments to something like below ? :
high frequency clock updates expected
=>
expected accuracy is based on high frequency clock updates
I do not want to change the Windows part until any failure is observed but can update the comment for consistency.

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@dholmes-ora dholmes-ora Nov 17, 2025

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This is wrong. The "expected" accuracy is still 10ms or even 1ms, it is never 32ms. The test may need to wait longer but changing this value makes no sense.

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@plummercj plummercj Nov 17, 2025

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I think the real issue is that EXPECTED_ACCURACY is incorrectly named. It is being used as a max amount of elapsed time, not as an "accuracy" value. The comment on the WIN32 part just adds to the confusion. The "max elapsed time" has to be 16 ms because that is the clock is only accurate to 16ms, so even 1ms of elapsed times will show up as 16ms. The comment "16ms is longest clock update interval" should read "shortest", not "longest".

EXPECTED_TIMEOUT_ACCURACY_NS also seems to be misnamed.

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@sspitsyn sspitsyn Nov 17, 2025

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Thank you, Chris. My intention was to fix this intermittent failure and achieve better stability. My preference would be to get rid of these troublesome and useless checks instead of fixing confusing constant names and comments.

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@dholmes-ora dholmes-ora Nov 18, 2025

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The comment "16ms is longest clock update interval" should read "shortest", not "longest".

No it is the longest interval between clock updates (actually 15.259) based on the old PIT timer (1/65536). Modern hardware will have 10ms or even 1ms.

The code expects to see at most one timer-tick of elapsed time, hence the name and the value.

#endif

/* scaffold objects */
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