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Entry  10 Jan 2019, Konstantin Olchanski, Info, removal of cm_watchdog() 
    Reply  21 Jan 2019, Konstantin Olchanski, Info, removal of cm_watchdog() 
       Reply  24 Jan 2019, Konstantin Olchanski, Info, removal of cm_watchdog() 
Message ID: 1435     Entry time: 10 Jan 2019     Reply to this: 1439
Author: Konstantin Olchanski 
Topic: Info 
Subject: removal of cm_watchdog() 
cm_watchdog() has been removed from the latest midas sources. The watchdog functions performed by cm_watchdog() were 
moved to cm_yield() - those are - maintaining odb and event buffer "last active" timestamps and checking for and removing of 
timed-out clients.

Those who write midas programs should ensure that they call cm_yield() at least every 1-2 seconds (for the normal 10 second 
timeout settings). As always, before calling potentially time consuming operations, such as accessing slow responding 
hardware, one should increase or disable their watchdog timeout.

Those who write midas programs that do not use cm_yield() (i.e. the mserver), should call cm_periodic_tasks() instead with 
the same period as described for cm_yield() above.

Removal of cm_watchdog() solves many problems in the midas code base:
- firing of cm_watchdog() at random times in random places makes it difficult to do static code path analysis (call paths, etc) - 
this is needed to ensure correct multithread locking, etc
- ditto caused trouble with multithread locking when cm_watchdog() fires *inside* the pthread mutex locking library itself 
causing mutexes to be in an inconsistent state. This had to be kludged against in the ODB multithread locks - now this kludge 
can be removed.
- many non-midas codes in experiment frontends, etc was not expecting and did not correctly handle firing of the 
cm_watchdog() SIGALARM at random times (i.e. select() with timeout returned too soon, etc).
- today, UNIX signals are pretty obscure, best avoided. (i.e. interaction of signals and threads is not super will defined, etc).

commits up to (and including) plus merge of branch feature/remove_cm_watchdog

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