Experimental Physics and
Industrial Control System

Sonya Hoobler <[email protected]> · Tue, 9 Sep 2014 15:28:47 -0700 (PDT)

Hi Mark,

At LCLS we have VME crates (and other devices) that we monitor and control

with soft iocs using asyn + streamdevice. There are many crates and it is

not uncommon for one or more to be offline.

We have noticed that if there is an offline device, it can take minutes

for the monitoring soft ioc to exit. This delay is the time it takes for

the connect() networking routine to try to connect to the offline device.

The socket is blocking and connect() takes about 3 minutes on our system.

(More detail: the delay occurs while drvAsynIPPort cleanup() waits for the

synchronousLock mutex. The mutex is held by asynManager portThread() or

connectAttempt() while drvAsynIPPort connectIt() calls connect().)

I am curious what your thoughts are on this and whether you think it is

worthwhile to pursue a change to reduce the shutdown time under these

conditions. One option could be to modify connectIt() to temporarily set

the socket to non-blocking during connect() and use select() to enforce a

specified timeout. Then the socket could be set back to blocking. One

potential downside of this could be introducing a new timeout which might

not suit all systems.

A little more detail about our system: the soft iocs run on Linux RHEL5

32-bit servers, soon to be RHEL6 64-bit. We are using base R3-14-12,

asyn4-21, streamdevice-R2-5, TCP/IP telnet-style connections, e.g.:

drvAsynIPPortConfigure ("crat-test-bd01","crat-test-bd01:23",0,0,0)

Thanks,
  Sonya

Sonya Hoobler
SLAC National Accelerator Laboratory
[email protected]

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System