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

[Kevin Walls]

On Tue, 25 Mar 2025 17:57:56 GMT, Leonid Mesnik <lmesnik at openjdk.org> wrote:

> The only one generic question: doesn't it makes sense to update JMX to retry several times if Windows 2029 returns -1.0 or undefined to make JDK more reliable? Are tools like JMC/VisualVM suffer from this issue or they make a lot of request to track data and can live with this.

Yes, I was bit worried about adding the overhead of repeating the call, maybe 5 times, with short sleeps, in the MBean CPU monitoring code.  It's been this way "forever", and is documented to return a negative value when info is "not available", so it is still delivering what it promises.  
In our CI it's only Windows Server 2019 10.0 (amd64) where we see a problem.  I don't see actual user reports of it being a problem.  Once the call "works" it seems stable,  so maybe the test is fast to startup and sees the problem.  I think it's better to have the retry on (rare) failure than have the test delay to try and miss the problem, I don't know how reliable that would be without more investigation (which does not seem worthwhile right now).  That may also relate to no reports from JMC/JConsole, but I'm just speculating now. 8-)

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PR Comment: https://git.openjdk.org/jdk/pull/24186#issuecomment-2752526446