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Re: ps shows same process more than once


On Mon, Dec 02, 2013 at 10:24:55AM -0500, Christopher Faylor wrote:
>On Mon, Dec 02, 2013 at 01:47:09PM +0800, George M. Florendo wrote:
>>On 11/29/13, Christopher Faylor wrote:
>>> On Thu, Nov 28, 2013 at 10:55:04AM -0500, Christopher Faylor wrote:
>>>>On Thu, Nov 28, 2013 at 02:08:13PM +0100, Corinna Vinschen wrote:
>>>>>On Nov 28 15:20, George M. Florendo wrote:
>>>>>> Hi,
>>>>>>
>>>>>> I run a non cygwin apache process named httpd.exe.  Checking it with
>>>>>> "ps -W" shows a listing of the same process (with PID 4560 in this
>>>>>> case) twice.
>>>>>>
>>>>>> $ ps -W | grep httpd
>>>>>>      4560    1604    4560       5304  pty0    1000 09:55:21
>>>>>> /home/georgeflorendo/wamp/bin/apache/Apache2.4.4/bin/httpd
>>>>>>      4560    1604    4560       5304  pty0    1000 09:55:21
>>>>>> /home/georgeflorendo/wamp/bin/apache/Apache2.4.4/bin/httpd
>>>>>>      7508       0       0       7508  ?          0 15:09:50
>>>>>> C:\cygwin\home\georgeflorendo\wamp\bin\apache\Apache2.4.4\bin\httpd.exe
>>>>>>
>>>>>> Doing a "ps aux" shows it only once.
>>>>>>
>>>>>> $ ps aux
>>>>>>       PID    PPID    PGID     WINPID   TTY     UID    STIME COMMAND
>>>>>>      1340    7856    1340       5720  pty5    1000 15:13:50 /usr/bin/ps
>>>>>>      1604    4008    1604       2292  pty0    1000 09:17:01
>>>>>> /usr/bin/bash
>>>>>>      4008       1    4008       4008  ?       1000 09:17:00
>>>>>> /usr/bin/mintty
>>>>>>      4560    1604    4560       5304  pty0    1000 09:55:21
>>>>>> /home/georgeflorendo/wamp/bin/apache/Apache2.4.4/bin/httpd
>>>>>>
>>>>>> <snipped>
>>>>>>
>>>>>> Is it correct that ps -W shows the same process twice?
>>>>>
>>>>>Not exactly but it could happen.  Can you try the latest snapshot Cygwin
>>>>>DLL from http://cygwin.com/snapshots/ and see if it fixes the problem?
>>>>
>>>>I don't see anything in the ChangeLog which would affect this and I'd
>>>>be concerned if there was.
>>>>
>>>>There are scenarios where two different windows pids can be associated
>>>>with the same Cygwin pid.  You should only see it when you do a "ps -W".
>>>>
>>>>So, AFAICT, the correct answer to the "Is it correct" is "Yes'.
>>>
>>> Oops.  Sorry.  Just noticed that the pids weren't "different".  There
>>> are still pathological situations where a pid can show up twice when
>>> doing a "ps -W".  I've seen the issue before but fixing it would involve
>>> a global process lock which would slow down Cygwin for the benefit of
>>> a more accurate "ps -W".
>>
>>Oh, I'm sorry too.  Didn't get to read your first sentence earlier.
>>I'd rather have a faster cygwin more than a more accurate "ps -W".
>>
>>Thanks for all your help.
>
>Thanks for understanding.  I will try to revisit this code sometime in
>the near future to see if I can do something about this case.  I had a
>glimmer of an idea about how to fix this in the thinking room recently.

This problem should be fixed in the latest snapshot.

cgf

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