RFR: 8344671: Few JFR streaming tests fail with application not alive error on MacOS 15 [v5]

[Kevin Walls]

On Mon, 31 Mar 2025 18:02:12 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-8334671: minor changes requested by @dholmes

Looks good.

(I'm sure the Linux and MacOS VirtualMachineImpl() attach/timeout loops are almost identical now, not a problem but maybe one day we can de-duplicate them.)

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Marked as reviewed by kevinw (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/24085#pullrequestreview-2735291287