RFR: 8279124: VM does not handle SIGQUIT during initialization [v2]

[David Holmes]

On Wed, 19 Jan 2022 09:35:01 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

>> because JVM_HANDLE_XXX_SIGNAL is installed in os::init_2(), it's safe to use log. I added a log entry with the tag os+init.  -Xlog:os+init=info will print out a message "ignore BREAK_SIGNAL in the initialization phase." I also update the testing example in the description section.
>
> Sorry for being difficult, but I would not do UL logging here. UL is heavyweight, and a shifting target too, because folks like to extend it with new capabilities. God knows what log_info really does (initialization, network traffic, accessing thread locals...) or will do in the future.
> 
> I'd keep it simple stupid and either just use write to fd=2 or fprintf(stderr). The former is safe to use in signal handling contexts, not sure about the latter. Otherwise maybe David is right and we skip the output altogether.

Do not use UL from a signal handler! It is not safe. printf may not even be safe.

I really do not think we need to try and be this accommodating to what seems an unrealistic scenario.

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PR: https://git.openjdk.java.net/jdk/pull/7003