jmx-dev RFR: 8351002: com/sun/management/OperatingSystemMXBean cpuLoad tests fail intermittently [v3]

[Kevin Walls]

On Tue, 25 Mar 2025 16:35:04 GMT, Chris Plummer <cjplummer at openjdk.org> wrote:

>> Kevin Walls has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   stricter check
>
> test/jdk/com/sun/management/OperatingSystemMXBean/GetProcessCpuTime.java line 60:
> 
>> 58:     // Careful with these values.
>> 59:     private static final long MIN_TIME_FOR_PASS = 1;
>> 60:     private static final long MAX_TIME_FOR_PASS = Long.MAX_VALUE / 1000;
> 
> I think this is still 9,223,372 seconds. Seems it should be lower. It might be best to work in the opposite direction. Decide how many seconds and then multiply that by 1,000,000,000.

Yes... 
My concern was that 0x7FFFFFFFFFFFFFFF if actually returned, must surely indicate a problem, and the test has been checking if a long is > Long.MAX_VALUE, which can't be useful.  So reducing it even slightly at least give the check some meaning.

I can reduce the value further...
The test obviously avoids guessing what the value should be, to avoid it varying too much one day, and causing a failure.

I've seen the test with -Xcomp, log ns value of 48,580,000,000 but there might be much slower runs out there.

If I use Long.max_value / 10000000 it would have to be about 20 times slower to cause a failure.

Long.max_value / 1000000 =     9,223,372,036,854
Long.max_value / 10000000 =      922,337,203,685
Xcomp example                     48,580,000,000

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PR Review Comment: https://git.openjdk.org/jdk/pull/24186#discussion_r2012976566