Many vert.x-worker threads blocked during startup

[miratx]

Many vert.x-worker threads blocked during startup

[andrewazores]

I have a hunch that this is related to or caused by #1388 . That PR didn't completely solve what it set out to (so #1402 has been in a draft trying to finish the job). I think it's probably worthwhile backing out the riskier parts of #1388 for the 2.3.0 release and putting the entire fix in #1402 for merge later, if it can be done.

[andrewazores]

@miratx how many target applications do you have across the K8S_NAMESPACES that your Cryostat instance is monitoring? I suspect that if there are ~20+ (the size of the worker thread pool) that's when this problem would manifest. If so then I can try to reproduce this, and then use that to test #1449 as a solution.

[miratx]

@andrewazores good point, it worked now OK for 17 targets, over 20 targets caused problem. Thanks!

[andrewazores]

Thanks very much for confirming @miratx . I think my PR #1449 will fix this report then.