RFR 10: 8184808 (process) isAlive should use pid for validity, not /proc/pid

Roger Riggs Roger.Riggs at Oracle.com
Tue Jul 18 19:01:13 UTC 2017

Hi Thomas,

Yes, if there is no access to the pid, then it can't report alive or 
not, and assume not.
If there access restrictions it will apply to the waitid/waitpid in the 
logic also and the answer will be at least consistent (and avoid a 
possible race
between //proc/pid/psinfo and kill state).

Thanks, Roger

On 7/18/2017 2:53 PM, Thomas Stüfe wrote:
> Hi Roger,
> I think this may fail if you have no permission to send a signal to 
> that process. In that case, kill(2) may yield EPERM and isAlive may 
> return false even though the process is alive.
> But then, I am not sure if that could happen in that particular 
> scenario, plus it may also mean that you do not have access to 
> /proc/pid either. So, I do not know how much of an issue this could be.
> Otherwise, the fix seems straightforward.
> Kind Regards, Thomas
> On Tue, Jul 18, 2017 at 8:46 PM, Roger Riggs <Roger.Riggs at oracle.com 
> <mailto:Roger.Riggs at oracle.com>> wrote:
>     Please review a fix for an intermittent failure in the
>     ProcessHandle OnExitTest
>     that fails frequently on Solaris.
>     ProcessHandle.isAlive is using /proc/pid/psinfo to determine if a
>     process is alive and it's start time.
>     However, it appears that the between the process exiting and the
>     reaping of its status, the
>     psinfo file indicates the process is alive but kill(pid, 0)
>     reports that is is not alive.
>     Depending on a race, the ProcessHandler.onExit may determine the
>     process has exited
>     but later isAlive may report it is alive.
>     To have a consistent view of the process being alive,
>     ProcessHandle.isAlive in its native implementation
>     should use kill(pid, 0) to determine if the process is
>     definitively determine if the process alive.
>     The original issue[1] will be kept open until it is known that it
>     is resolved.
>     Webrev:
>     http://cr.openjdk.java.net/~rriggs/webrev-alive-solaris-8184808/
>     <http://cr.openjdk.java.net/%7Erriggs/webrev-alive-solaris-8184808/>
>     Issue:
>     https://bugs.openjdk.java.net/browse/JDK-8184808
>     <https://bugs.openjdk.java.net/browse/JDK-8184808>
>     Thanks, Roger
>     [1] https://bugs.openjdk.java.net/browse/JDK-8177932
>     <https://bugs.openjdk.java.net/browse/JDK-8177932>

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