Defunct processes with 1.5.25-15; seemingly reproducible

[Huang Bambo]

2009/11/27 Dave Steenburgh <dave.steenburgh@gmail.com>
>
> cgf wrote:
> > Defunct processes are not necessarily indicative of a cygwin problem.
> > This could easily be a problem with gnuplot.
>
> Given the sum of my own limited knowledge of the problem at hand (in
> summary: every program involved is in my local cygwin directory), I
> figured it was best to ask here first.
>
> Dave Steenburgh wrote:
> > $ ps
> >      PID    PPID    PGID     WINPID  TTY  UID    STIME COMMAND
> > ...
> >     4164    1288    7684       5504    6 1003 23:49:20 <defunct>
> >     5392    3224    5984       6100    5 1003 23:49:06 <defunct>
> >     1452    5240    5984       8104    5 1003 23:49:06 <defunct>
> >     5240    3224    5984       4532    5 1003 23:49:06 <defunct>
> > ...
> >
> ...
> > The PIDs seem to be the same every time this happens.  Specifically, I
> > have seen 5240 and 1452 every time.  Whether that's significant, I
> > don't know.
>
> Now, this is interesting...  I killed those defunct processes with
> process explorer, and subsequently confirmed via ps, task manager, and
> process explorer that they were no longer running.  I began another
> session with gnuplot, and this time there are three:
>
> $ ps
> ...
>     5240    3224    5984       4532    5 1003 23:49:06 <defunct>
>     4164    1288    7684       5504    6 1003 23:49:20 <defunct>
>     5392    3224    5984       6100    5 1003 23:49:06 <defunct>
> ...
>
> For each of those, the entire row is identical to a row in my previous
> message.  Since I started the session around 14:00, and the last
> output file's modification timestamp is 17:21, I'd say the timestamps
> for those three processes are not reliable.  Is it possible that the
> original defunct processes were never truly killed?  If so, can they
> be killed without rebooting?
>
Those defunct function will disapear after parent process exist in *nix.
To avoid this condition, try to handle SIGCHLD and call wait/waitpid to
free resources used by child process

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