RFR: 8288984: Simplification in Shutdown.exit [v3]

[David Holmes]

On Tue, 5 Jul 2022 03:24:28 GMT, Ryan Ernst <duke at openjdk.org> wrote:

>> src/java.base/share/classes/java/lang/Runtime.java line 88:
>> 
>>> 86:      * <p> Shutdown is serialized such that only one invocation will run
>>> 87:      * shutdown hooks and terminate the VM with the given status code. That
>>> 88:      * invocation may be initiated via platform specific signal handlers. All
>> 
>> Why are we mentioning signal handlers here? How is that relevant?
>
> Signal handlers for eg SIGTERM invoke Shutdown.shutdown. That method holds the same lock as Shutdown.exit and runs shutdown hooks. So if a signal handler triggers shutdown, and before the system halts Runtime.exit is invoked, the status passed to Runtime.exit will be ignored.

First, the signal handlers actually invoke Shutdown.exit, not Shutdown.shutdown  - see Terminator.setup(). (If they did the latter, like DestroyJavaVM, then an exit(status) call from another thread could still do the final VM halt(status)

But now you are opening a can of worms. There are multiple ways for the VM to initiate termination - are you going to try and describe here how all of them potentially interact?  

What you are really stating here is that other parts of the JDK can invoke System.exit, but that is for them to specify where such things are specified, it isn't for exit() to try and list them all. All we have to do here is describe how multiple calls to exit() behave.

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PR: https://git.openjdk.org/jdk/pull/9351