Experimental Physics and
Industrial Control System

"Brian McAllister" <[email protected]> · Fri, 25 Jan 2002 12:25:05 -0500

SNL folks -

   ( Is William Lupton still responsible for the EPICS sequencer ?
     Or is Greg White the contact person now, as shown on the web page ?)

We are having a problem with one specific sequencer program where deleting
the task always results in breaking the shell, requiring a hard reboot to
restore the IOC to normal.

The task deletion is attempted because the program has become "stuck" in a
particular state (but not always the same one).  I'm fairly sure this is
due to problems with the program, but that is unresolved at this time.

It may be significant that this program accesses PVs on other IOCs.

Here is what happens (this is done from the console, not telnet) :

========

gall2> td "pam_seq"

tSeqCleanup: A call to "assert (semTake(client_lock, WAIT_FOREVER)==OK)" failed in ../access.c at 403
Please send a copy of the output from "tt (0x57926c)" and a copy of this message
to the author or "[email protected]"
This problem occurred in "@(#)Version R3.13.4 $2000/12/15 15:52:33$"

========

At this point the shell is unresponsive, so I can't use tt.
If I type "^C", I get:

========

 67124 _vxTaskEntry   +10 : _shell (1, 0, 0, 0, 0, 0, 0, 0, 0, 0)
 47abe _shell         +12e: 47adc ([1, 0, 3, 7f, 0])
 47c5a _shell         +2ca: _execute ([f95712, 1, 0, &_ioGlobalStdGet, 7464])
 47d78 _execute       +a6 : _yyparse ([0, 1, 0, f95712, 0])
 7f572 _yyparse       +546: 7df48 (72a900, 72a920)
 7e052 _yystart       +734: _td (72a630, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0)
 64054 _td            +32 : _taskDelete (7866c4)
 26bea _taskDelete    +12 : _taskDestroy ([7866c4, 1, ffffffff, 0, f955ec])
 26e9e _taskDestroy   +27e: _semQPut (7866c4)

========

I can provide the SNL code if that would be useful.

----
Brian McAllister                    Controls Programmer/Beam Physicist
[email protected]                        MIT-Bates Linear Accelerator
(617) 253-9537                                           Middleton, MA

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System