Hi Jocelyn,
We are starting to have more demand on our application using sedna as data
> store. We are getting the following error (also see our event.log
> attached):
>
> ERROR 28/02/2013 14:08:16 (SM student-awards pid=20818)
> [lock_table.cpp:visit:580]: (SE4705) Deadlock is detected.
> ERROR 28/02/2013 14:08:16 (TRN student-awards pid=21077 sid=45 trid=48)
> [locks.cpp:obtain_lock:204]: (SE4703) The transaction is a victim of
> deadlock resolution procedure.
>
Just try to run the same transaction again in case of this error. It's not
an error per se. It means that for some reason database is under pressure
now. A lot of transactions want to use the same resources (same collection
in your case it seems). Are you sure that you commit transactions as soon
as possible? If you have a lot of concurrent transactions make sure they
are short and simple. Maybe you should use read-only mode for some of them?
Anyway, we'll try to understand why there are so many deadlocks in your
case.
> Today our database went down three times and not sure why yet. We suspect
> that it might be caused by either a higher load or the deadlock situation.
>
I don't see this in event logs. I mean when database went down. Do you have
"fault*" folders near event logs? Can you send us full event logs? Btw,
which Sedna client/driver do you use?
> Also we want to increase the number of "allowed connections" from 50 to
> ??. Do you have any suggestion about the maxmum connections sedna can
> support? We are preparing ourselves to recompile sedna on our RedHat Linux
> and would like to change that parameter. BTW: Are there other parameters
> you know that we should "check" that might be useful before we re-compile?
>
Everything should work fine if you have simple transactions. We haven't
experimented with the maximum connections number for now. Probably, you
will need to tune linux kernel's parameters once more. As far as I remember
you don't need to change any other parameters, just increase:
#define CHARISMA_MAX_TRNS_NUMBER 50
#define MAX_SESSIONS_NUMBER 50
and
#define UPPER_SESSIONS_NUM_BOUND 100
Ivan Shcheklein,
Sedna Team
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