Re: Automatic deadlock detection

Your scenario doesn't fit the definition of a deadlock I don't
think...doesn't a deadlock require more than one resource?

lock escalation needs only one ressource for a deadlock:

transaction 1 reads a record with select into with isolation level uncommited read
transaction 2 reads the same record with the same isolation
now we have the situation, that none of both could update the record!!!

@ wait file 30: the grass isn't as good as it used to be, but they are still smoking !!!

60 seconds for a record lock is by fare too much, a record is locked for milliseconds, or as long as a silly programmer enabled a user to lock a record, while the programm is waiting for the next key stroke of the enter key from the user. or forever...
waiting for a record longer than for disappearing of a tablelock, what situation could someone have in mind for this nonsens???

D*B

Though I tried it with two tables, and still only get the SQL 913 error...

Perhaps you have to have WAITRCD = *NOMAX, for the system to kick out
the deadlock error?

Charles



On Tue, Jan 11, 2011 at 7:32 PM, Jonathon Creenaune
<jonathon@xxxxxxxxxxxxxx> wrote:

Does DB2 for iseries support deadlock detection? I can't get it to work. I'm
manually running the following sql commands in different transactions:


T1: set transaction isolation level RS;
T1: select * from aschema.atable where id = 1;

T2: set transaction isolation level RS;
T2: select * from aschema.atable where id = 1;

T1: update aschema.atable set acolumn = acolumn where id = 1; -- this
blocks, which is correct
T2: update aschema.atable set acolumn = acolumn where id = 1; -- this
blocks, which is correct


On DB2 LUW, after 10 seconds I get sql 911 reason 2, indicating that a
deadlock has been detected and one of the transactions has been rolled back.
The other one then proceeds.

On DB2 for iseries, after 30 seconds (the table's record lock wait time) I
get sql 913, indicating that the record lock wait time has been reached. No
deadlock is detected. I'm wondering if there's something I need to configure
to enable deadlock detection.

I'm running the tests on a v6r1 machine through jt400 6.1.

Any help is much appreciated,

Jonathon
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