I haven't found any hint to something abnormal in my log files yet.
However, we experienced the duplicate key problem some minutes ago
and I was able to track down the problem a bit.
Affected is only one single WebApp and these "Duplicat entry" errors
occured since yesterday, about 15:30. If I search for this exception
I can find this ID list:
$ cat x.log.2006-07-12 x.log | grep 'message from server'|uniq
Caused by: java.sql.SQLException: null, message from server:
"Duplicate entry '17048820' for key 1"
Caused by: java.sql.SQLException: null, message from server:
"Duplicate entry '17048821' for key 1"
Caused by: java.sql.SQLException: null, message from server:
"Duplicate entry '17048822' for key 1"
Caused by: java.sql.SQLException: null, message from server:
"Duplicate entry '17048823' for key 1"
Caused by: java.sql.SQLException: null, message from server:
"Duplicate entry '17048824' for key 1"
Caused by: java.sql.SQLException: null, message from server:
"Duplicate entry '17048825' for key 1"
Caused by: java.sql.SQLException: null, message from server:
"Duplicate entry '17048826' for key 1"
Caused by: java.sql.SQLException: null, message from server:
"Duplicate entry '17048827' for key 1"
Caused by: java.sql.SQLException: null, message from server:
"Duplicate entry '17048828' for key 1"
Caused by: java.sql.SQLException: null, message from server:
"Duplicate entry '17048829' for key 1"
Caused by: java.sql.SQLException: null, message from server:
"Duplicate entry '17048830' for key 1"
Caused by: java.sql.SQLException: null, message from server:
"Duplicate entry '17048831' for key 1"
Caused by: java.sql.SQLException: null, message from server:
"Duplicate entry '17048832' for key 1"
Caused by: java.sql.SQLException: null, message from server:
"Duplicate entry '17048833' for key 1"
Caused by: java.sql.SQLException: null, message from server:
"Duplicate entry '17048834' for key 1"
Caused by: java.sql.SQLException: null, message from server:
"Duplicate entry '17048835' for key 1"
Caused by: java.sql.SQLException: null, message from server:
"Duplicate entry '17048836' for key 1"
Caused by: java.sql.SQLException: null, message from server:
"Duplicate entry '17048837' for key 1"
Caused by: java.sql.SQLException: null, message from server:
"Duplicate entry '17048836' for key 1"
Caused by: java.sql.SQLException: null, message from server:
"Duplicate entry '17048838' for key 1"
Caused by: java.sql.SQLException: null, message from server:
"Duplicate entry '17048839' for key 1"
It seems as if one package of PKs (17048820 - 17048839 ) was double
used.
How does the PK magic of Cayenne work? Does each DataContext get its
own set of IDs?
Christian
Am 12.07.2006 um 23:40 schrieb Andrus Adamchik:
Hmm.. MySQLPkGenerator runs "UNLOCK" in the finally block. Of
course if the connection goes down or something else equally bad
happens during unlock, then you can end up locking the table. I'll
be curious to know what exactly happened, as we may improve the
unlock reliability as a result.
Andrus
On Jul 12, 2006, at 5:29 PM, Christian Mittendorf wrote:
Yes, all of our applications on this database are cayenne based.
I will have a look at the logs tomorrow and see if I can find some
other exceptions...
Thanks,
Christian
Am 12.07.2006 um 19:56 schrieb Gentry, Michael ((Contractor)):
These could be related, then. I know the MySQL adapter has to
lock the
auto_pk_support table to generate keys and perhaps something
happened to
leave the table locked. Did you see any other exceptions?
Also, you said you have multiple applications hitting the same
database.
Are all of these applications Cayenne-based?
Thanks,
/dev/mrg
-----Original Message-----
From: Christian Mittendorf [mailto:[EMAIL PROTECTED]
Sent: Wednesday, July 12, 2006 1:50 PM
To: [email protected]
Subject: Re: Duplicate Key Problem
We don't use the autoincrement from MySQL.
Am 12.07.2006 um 16:35 schrieb Gentry, Michael ((Contractor)):
Are you using MySQL's autoincrement feature for the PKs or the
auto_pk_support table from Cayenne?
-----Original Message-----
From: Christian Mittendorf [mailto:[EMAIL PROTECTED]
Sent: Wednesday, July 12, 2006 4:29 AM
To: [email protected]
Subject: Duplicate Key Problem
Hello!
We are running a MySQL 5.0 server using InnoDB tables for our
applications. We have multiple web applications accessing this same
database and the system is running smooth and without problems
(almost).
But yesterday we were experiencing some strange errors. During the
afternoon some CayenneRuntimeExceptions appeared in the log file,
which were caused by:
Caused by: java.sql.SQLException: null, message from server:
"Duplicate entry '4353880' for key 1"
A bit later other CayenneRuntimeException appeared. For those
exceptions the cause was:
Caused by: java.sql.SQLException: Deadlock found when trying to get
lock; Try restarting transaction, message from server: "Lock wait
timeout exceeded; try restarting transaction"
I'm now wondering, are both errors related to each other?
There are, from my point of view, two possible causes for the
"Duplicate entry..." message:
- two Insert statements on the same object, which might be possible
if the application is clustered, which our applications are not, or
- dual use of the same key in different objects
Has anybody else experienced something like that? Are there any
hints
what I might do to avoid such situations?
Christian
