RFR: 8344671: Few JFR streaming tests fail with application not alive error on MacOS 15 [v3]

[David Holmes]

On Thu, 27 Mar 2025 22:27:05 GMT, Larry Cable <duke at openjdk.org> wrote:

>> on both Linux and MacOS libattach utilizes UNIX signal (QUIT) to cause a target JVM (attachee) to create the socket file used as transport for subsequent jcmds (and other attach based interactions) and to listen upon that for such.
>> 
>> it should be noted that the default behavior for QUIT (if not blocked or caught) is to terminate the signalled process.
>> 
>> during the early lifetime of a JVM, its signal handlers are not yet installed, and thus any signal such as QUIT will cause the
>> default behavior to occur, in this case the JVM will be terminated.
>> 
>> this is why some tests are failing with "not alive"
>> 
>> the "fix" is similar in nature to that already implemented for linux (however using a different OS dependent mechanism to obtain the attachee JVM's signal masks: sysctl(2)).
>> 
>> the method "checkCatchesAndSendQuitTo" will now obtain the "attachee" JVM signal masks and only kill(QUIT) if the
>> current masks indicate that the JVM's signals are now being handled.
>> 
>> the behavior in the success case is now identical to the previous implementation, however should the target JVM not 
>> become "ready" (signal handlers installed) prior to the attach "timeout" occurring the attach operation will throw an
>> "AttachNotSupportedException" with a suitable error message.
>> 
>> see also: https://bugs.openjdk.org/browse/JDK-8350766
>
> Larry Cable has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - Merge branch 'JDK-8344671' of github.com:larry-cable/jdk into JDK-8344671
>  - JDK-8344671: removed JFR tests from problemlist resolved by this fix

Looks good. Just a couple of remaining nits. Thanks.

src/jdk.attach/macosx/native/libattach/VirtualMachineImpl.c line 148:

> 146: 
> 147:         if (caught && !ignored) {
> 148:             if (kill((pid_t)pid, SIGQUIT)) {

Style nit: no implicit booleans
Suggestion:

            if (kill((pid_t)pid, SIGQUIT) != 0) {

-------------

Changes requested by dholmes (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/24085#pullrequestreview-2724337304
PR Review Comment: https://git.openjdk.org/jdk/pull/24085#discussion_r2017961485