Differences in Process#destroy() between Windows and Unix implementations

[Rémi Forax]

The soft way to kill a process on windows to send a WM_CLOSE/WM_QUIT.
http://stackoverflow.com/questions/2055753/how-to-gracefully-terminate-a-process

Rémi


Le 10/11/2010 10:46, Andreas Kohn a écrit :
> On Wed, 2010-11-10 at 06:02 +1000, David Holmes wrote:
>    
>> Hi Andreas,
>>
>> On 10/11/2010 5:31 AM, Andreas Kohn wrote:
>>      
>>> there seems to be a difference in behavior between Process#destroy()
>>> implementations on Windows and !Windows: on Windows TerminateProcess()
>>> [1] is called, which gives the process no way to react or in any way
>>> intercept the termination, while on Unix a simple SIGTERM is send which
>>> the process can just decide to ignore. [2]
>>>
>>> Is this intentional?
>>>        
>> As I understand it: yes and no. :)
>>
>> The problem is that neither version is necessarily what you always want.
>> SIGTERM is nice in that it allows the process to execute cleanup handlers
>> etc (such as an exec'ed JVM!) but I don't think Windows has an equivalent,
>> so we have to use TerminateProcess. On the flip side if SIGTERM fails we
>> have no way to really kill an errant process.
>>
>>      
> Thanks for the confirmation that this is an unfortunate leak of the OS
> details into the java library. Looking through the bugdatabase I found
> various related bugs now, so I did not file a new RFE just now:
>
> http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4073195
> http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4333183
> http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6960070
>
>    
>> What we really need is two destroy methods: one that tries to
>>      
> terminate
>    
>> nicely and one with "extrene prejudice". But again I'm not sure that Windows
>> would support that. I suppose we could also define the destroy() method to
>> try both approaches, if available, eg SIGTERM wait a while SIGKILL. But then
>> we need a way to specify "wait a while".
>>      
> I think if you have the ability as API user to indicate to Process
> whether it should "stop, please" or "die!" it would be perfectly enough.
>
> Windows may not provide the APIs for the "please" part, but then again
> this is as mentioned above and in the bugs very system specific, so
> having the Windows implementation do nothing in the "please" case should
> be fine, as this would be still classify as "best effort".
>
> Windows:
> Process#stop() {
>    // nothing, windows doesn't do it
> }
> Process#destroy() {
>    TerminateProcess();
> }
>
> Unix:
> Process#stop() {
>    kill(SIGTERM);
> }
> Process#destroy() {
>    kill(SIGKILL);
> }
>
> Regards,
> --
> Andreas
>
>    
>> David Holmes
>>
>>      
>>> I do prefer the Windows behavior, mainly because I do create processes
>>> once in a while that simply fail to terminate due to bugs in their
>>> implementation, and having Process#destroy() as a last, and terminal,
>>> resort is very helpful to work-around those issues.
>>>
>>> Regards,
>>> --
>>> Andreas
>>>
>>> [1]
>>> http://hg.openjdk.java.net/jdk7/jdk7/jdk/file/d87c1c06bbf9/src/windows/native/java/lang/ProcessImpl_md.c
>>> [2]
>>> http://hg.openjdk.java.net/jdk7/jdk7/jdk/file/d87c1c06bbf9/src/solaris/native/java/lang/UNIXProcess_md.c
>>>
>>>
>>>        
>    

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