Experimental Physics and Industrial Control System
Hi,
Today, We encountered a strange phenomena on IOC. Suddenly, we have lost
CA connections from
three IOCs. These IOCs had a long record of stable operation and there
were no modification
in software including database recently. Running spy command on these IOCs,
we found that one of "CA client" task eats up more than 90% of CPU time
on these IOCs.
Eventually we found a cause of phenomena. One of reasons of this trouble
is a record with NULL string as its name. All three of IOCs were loaded
a NULL named EPICS record. These records did not cause any problem,
until I run a CA client program which search for a NULL named record!
dbLoadRecords commands in EPICS R3.13.1 accepts a NULL named record
without a error message.
CA library on WS also accepts NULL string as a record name. Python/CA,
which I used to write a client, does not check it also. A database file
(.db) was created by a PL/SQL scripts in the ORACLE database and was not
checked by any dbtools before load it on IOCs. ( We use EPICS R3.13.1
with VxWorks5.3 on PowerCore6750/6603 from Force Computer)
So when you encounters "CA client" library which eats up a lot of CPU,
please check a NULL named record on the IOC!
Noboru Yamamoto
KEKB control group
KEK, Accelerator Lab.
Tsukuba, JAPAN
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