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Entry  07 May 2009, Konstantin Olchanski, Info, mhttpd now uses mtransition 
    Reply  21 May 2009, Konstantin Olchanski, Info, mhttpd now uses mtransition 
       Reply  02 Jun 2009, Konstantin Olchanski, Info, mhttpd now uses mtransition 
          Reply  26 Jun 2009, Konstantin Olchanski, Info, mhttpd now uses mtransition 
Message ID: 571     Entry time: 07 May 2009     Reply to this: 583
Author: Konstantin Olchanski 
Topic: Info 
Subject: mhttpd now uses mtransition 
mhttpd function for starting and stopping runs now uses cm_transition(DETACH) which spawns an 
external helper program called mtransition to handle the transition sequencing. This helps with the old 
problem of looking at a blank screen for a long time if some frontends take a long time to process run 
transitions. Now mhttpd returns right back and shows start "starting run", "stopping run", etc as 
appropriate.

svn rev 4484 (some bits of this feature are present in rev 4473 and later).
K.O.

P.S. In one of our experiments, I sometimes see mhttpd getting "stuck" when starting or stopping a run 
using this feature. strace shows it is stuck in repeated calls to wait(), but I am unable to reproduce this 
problem in a test system and it happens only sometimes in the experiment. When it does, mhttpd has to 
be restarted. Replacing system("mtransition ...") with ss_sysem("mtransition ...") seems to fix this problem, 
but there are downsides to this (mtransition debug output vanishes) so I am not committing this yet.
K.O.
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