Patricia,
I am using Sequoia 2.10.9 for a proof of concept. The configuration I
have is using one Sequoia controller, with 2 MySQL backends (Raidb1).
All tables are Innodb.
Each backend is created on a separate MySQL server, and the recovery
db is collocated with one of the backends. The 2 MySQL servers are
located on 2 different machines, so perhaps a network latency can also
interfere.
Everything works fine, until I try load testing this configuration. If
I run a JMeter test for 5 concurrent users, I have a lock error on one
of the backends, which is disabled as result of the lock.
*********************************
2008-01-21 18:49:03,312 ERROR backend.DatabaseBackend.cg113-seq2
Request 'update log_call_session set call_type=?,...' failed on
backend cg113-seq2 but 1 succeeded (java.sql.SQLException: Lock wait
timeout exceeded; try restarting transaction)
2008-01-21 18:49:03,312 WARN backend.DatabaseBackend.cg113-seq2 Task
execution failed (java.sql.SQLException: Request 'update
log_call_session set call_type=?,...'
***********************************
Actually if you had a deadlock, you should experience the same error on
both backends. If only one backend deadlocks it means that you have a
configuration problem. Possible causes are:
- your backends are not properly synchronized and actually their config
(my.cnf) or content differ
- a process is executing queries directly on one backend without going
through Sequoia (locking will be completely messed up in that case)
- if you are using a single Sequoia controller, I guess that you don't
use group communication so the settings should not be an issue there.
- try to change <WaitForCompletion policy="first"/> to
<WaitForCompletion policy="all"/> in case there would be a
synchronization issue in the asynchronous execution management code.
Keep us posted with your findings.
Emmanuel
--
Emmanuel Cecchet - Research scientist
EPFL - LABOS/DSLAB - IN.N 317
Phone: +41-21-693-7558
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