RFR: 8292695: SIGQUIT and jcmd attaching mechanism does not work with signal chaining library [v4]

[David Holmes]

On Fri, 9 Sep 2022 08:27:41 GMT, Man Cao <manc at openjdk.org> wrote:

>> Hi all,
>> 
>> Could anyone review this bug fix? See https://bugs.openjdk.org/browse/JDK-8292695 for details.
>> 
>> I changed the temporary handler for SIGQUIT to use a dummy function, and use `os::signal()` to set it up, just as `os::initialize_jdk_signal_support()` does.
>> It is possible that just moving the `set_signal_handler(BREAK_SIGNAL, false);` in `install_signal_handlers()` outside of the window bounded by `JVM_{begin|end}_signal_setting()` could also fix this bug. However, `set_signal_handler()` and `JVM_HANDLE_XXX_SIGNAL()` are currently used for signals that support chaining and periodically check, which do not apply to SIGQUIT. I think it is cleaner to use different functions for SIGQUIT.
>> 
>> I also added a test to check that sending SIGQUIT should produce a thread dump on stdout, with and without using libjsig.so.
>> 
>> -Man
>
> Man Cao has updated the pull request incrementally with one additional commit since the last revision:
> 
>   address comments in test

Messing around with initialization order always makes me very nervous. While this may have solved the problem at hand it is far from clear to me that it has not introduced unexpected behaviour in other situations - situations that our testing is unlikely to expose.

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PR: https://git.openjdk.org/jdk/pull/9955