Re: vwait behavior

On Mar 6, 8:52 pm, Donald Arseneau <a...@xxxxxxxxx> wrote:
On Mar 5, 8:46 pm, rfwoode...@xxxxxxx wrote:





I've been wrestling with this problem for several days now.  I run the
following loop on a linux (red hat) web server and it will run fine
for sometimes up to 2 or 3 days before it crashes.  Most often it runs
for less than 48 hours.  (I know it was not due to a server crash -
according to uptime.)

Is there something wrong with the way I'm implementing the pause proc
that causes some weird behavior?

Thanks for any help!

# pauses for  n  milliseconds
proc pause { {msecs 1000} } {
   global gv;
   after $msecs "set vpause 1"
   vwait vpause

}

My guess is you are crashing due to stack overflow.  The problem is
that Tcl events / event handlers are not independent, but are stacked;
search for "recursive event loop".  If some event occurs while you are
paused, the pause cannot return when its time is up, but can only
return when the nested event handler is complete.  If you have some
fraction of events that take a long time to handle or invoke [pause]
then the stack will keep growing.

Doesn't apply here since there's no way for vwaits to nest (assuming
there is no other code than the one posted): the only place [vwait] is
called is within [pause] which is called in a synchronous [while].

Doug: This one beats me... Two questions:
- can you get the standard error of the process ? empty ?
- can you run strace -tt -o somefile yourprocess, until it exits, and
post back the end of the trace ?

-Alex

.

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