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

[Thomas Stuefe]

On Wed, 19 Jan 2022 09:20:07 GMT, Xin Liu <xliu at openjdk.org> wrote:

>>> This is in the signal handler. Is it safe to print message or do something complex?
>> 
>> raw write to stdout should be fine I think.
>> 
>>>I would not print anything here, first because it is in the signal handler and secondly I don't think it is needed. No real thread dump usages are going to hit a VM that hasn't initialized yet IMO.
>> 
>> Might be nice for the user to know why his jcmd or kill -3 gets ignored though.
>
> 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.

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