Sometimes when running JDK11+ in CI I see:

[11.028s][warning][os,thread] Failed to start thread - pthread_create failed (EAGAIN) for attributes: stacksize: 2048k, guardsize: 0k, detached.

What does this warning mean, and why is it shown by default (on JDK11+, not on JDK8)?
The application does continue to run after the warning, so I think pthread_create() was retried and succeeded.

It would be useful if this warning also showed the thread name.

If it's literally pthread_create() returning EAGAIN, is there any point to show this warning by default if retrying pthread_create() works? I would think not.

To make it worse, this is output on STDOUT, and so messes up the application output, and causes transient CI failures, while there seems to be no semantic problem.