database-deadlocks

I keep getting this exception in my Tomcat log: com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector run WARNING: com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector@76b28200 -- APPARENT DEADLOCK!!! Creating emergency threads for unassigned pending tasks! com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector run WARNING: com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector@76b28200 -- APPARENT DEADLOCK!!! Complete Status: Managed Threads: 3 Active Threads: 3 Active Tasks: com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@1201fd18

I have searched for quite some time now and can't found a solution to my problem. We are using SQLAlchemy in conjunction with MySQL for our project and we encounter several time the dreaded error: 1213, 'Deadlock found when trying to get lock; try restarting transaction'. We would like to try to restart the transaction at most three times in this case. I have started to write a decorator that does this but i don't know how to save the session state before the fail and retry the same transaction after it ? (As SQLAlchemy requires a rollback whenever an exception is raised) My work so far, def

I am working on a theory basis here, I want to make sure all my bases are covered. I have read quite a bit into InnoDB with Java and how deadlocks can occur no matter what query you are running. Although I am pretty clued in with the theory and best practices, I am pretty much clueless on how to implement the catch all mechanism of reissuing transactions when a deadlock occurs. Are there specific exceptions to listen out for? Is the exception only thrown after I call connection.commit() or can it occur as soon as I execute a PreparedStatement ? Should things be running in a loop with a limit

I am new for PostgreSQL. I want to simulate deadlock for this schedule: How to simulate deadlock in PostgreSQL? Is it possible at all? How to lock particular column? EDIT: BEGIN; UPDATE deadlock_demonstration SET salary1=(SELECT salary1 FROM deadlock_demonstration WHERE worker_id = 1 FOR UPDATE)+100 WHERE worker_id=1; SELECT pg_sleep(5); commit; SELECT salary2 FROM deadlock_demonstration WHERE worker_id = 1 FOR UPDATE; In another screen, I have run this BEGIN; UPDATE deadlock_demonstration SET salary2=(SELECT salary1 FROM deadlock_demonstration WHERE worker_id = 1 FOR UPDATE)+200 WHERE worker

Some database features, such as SELECT ... FOR UPDATE and ON DELETE CASCADE , are implicitly vulnerable to deadlocks because the database does not specify what locking order will be used. I found two discussions that hint that this behavior isn't specified by the SQL standard, not to mention specific implementations. As such, I'm operating under the assumption that we cannot control the locking order (at least, it's not obvious how to do so). How are we supposed to avoid database deadlocks if we cannot rely on the locking order? If we're not supposed to avoid deadlocks (you're going to have to

I use PostgreSQL 9.2, and I do not use explicit locking anywhere, neither LOCK statement nor SELECT ... FOR UPDATE . However, recently I got ERROR: 40P01: deadlock detected . The query where deadlock was detected is wrapped in transaction block though. Anyway, how comes it? You don't need any explicit LOCK to go into a deadlock. Here's a very simple demo from scratch with only INSERTs: create table a(i int primary key); create table b(i int primary key); Session #1 does: begin; insert into a values(1); Then session #2 does: begin; insert into b values(1); insert into a values(1); -- here it

Does oracle keeps any history about deadlocks? e.g. Can i know which sqls were executed when the deadlock was detected, and oracle exception ORA-00060 (deadlock detected while waiting for resource) is thrown? Thanks in advance. There's no history built-in to the database, however, when a deadlock occurs, a couple of things happen. First, it gets logged to the alert.log. Second, a trace file is written. So, there's some history recorded there. The tracefile will contain many useful bits of information, such as: - deadlock graph - SQL that encountered the deadlock - other statements involved in