Mysql deadlock found9/28/2023 I have reduced deadlock by fetching all items in one query, but still get deadlocks. I don't understand why the deadlocks are occurring. Item = s.query(WorkerInProgress).with_for_update().order_by( # Fetch the latest item and add a new one WorkerInProgress.processgroup_id != 'finished!locked', WorkerInProgress.processgroup_id != 'finished', WorkerInProgress.processgroup_id != processgroup_id, Item = s.query(WorkerInProgress).with_for_update().filter( #Take first matching object if available / Maybe some workers failed def next_slice(self, s, processgroup_id, itemcount): I did tried to increment a retry counter in the offset = -1 entity as well. TL DR: your concurrent insert from multiple threads to a table is causing deadlocks. To break from this loop, MySQL throws errors and calls this a 'deadlock'. I get deadlocks even all access is serialized. However, when two threads are fighting to acquire a lock - neither will ever acquire it - which puts is in an infinite loop. As far as I know and read so many time dead locks only happens when one transaction is locking resource A and waiting for B and another transaction does the opposite. Session handling, rollback and deadloc handling are handled outside. Dead Locks between an insert ignore and and an update Asked 7 years, 4 months ago Modified 7 years, 4 months ago Viewed 5k times 2 Using MySQL InnoDB. I am currently running only concurrent calls on the method next_slice. I have reduced my code to a minimal state. # The work with the index -1 always exists.į = s.query(WorkerInProgress).with_for_update().filter( It's simplified, as selectors are removed. Every thread and process should wait here, till it gets the lock. I noticed that there are so many errors occur related to deadlock. This code is executed on the first call in every function. I have a running app with concurrency transactions in it. I have already serialized the access, but still get a deadlock error. : () 1213 (40001): Deadlock found when trying to get lock try restarting transaction. LATEST DETECTED DEADLOCK - 10:36:37 0x7fe606788700 (1) TRANSACTION: TRANSACTION 492758175, ACTIVE 0 sec starting index read mysql tables in use 1, locked 1 LOCK WAIT 3 lock struct (s), heap size 1136, 3 row lock (s) MySQL thread id 2871743, OS thread handle 140625951213312, query id. If I don't get the permanent solution very soon, I am afraid I have to revert back to direct artisan commands.I have a big problem with a deadlock in an InnoDB table used with sqlalchemy. MySQLs InnoDB engine and PostgreSQLs engine resolve. PS: I am trying to find solution since last 2 months. A deadlock is caused when two or more transactions hold locks that the other transactions require. I am afraid of increasing number of queue workers because it will increase the number of deadlocks exponentially. PS: I need more queue workers because the number of queued jobs are more than 40,000 right now. I am sorry if I sound noob, but I really need help here! Any solutions? I don't want to switch to redis as I am not sending same messages to multiple people or something like that. I also thought about using redis but I think it won't make much difference except I will stop getting this error.īefore using queues for single job, I used to divide my collection into X parts and used to pass array of IDs to commands responsible for processing data. If you are going to comment there is no direct solution to this error, you have to understand why you are facing this issue, I know that! I am just queuing commands as stated in the Laravel documentation. A deadlock can also occur when such statements lock ranges of index records and gaps, with each transaction acquiring some locks but not others due to a timing issue. The issue is, I am getting following error in the laravel log and I know it's because of the multiple processes trying to lock the row at the same time in the Jobs table.ĭeadlock found when trying to get lock try restarting transaction (SQL: delete from 'jobs' where 'id' = 7405457) A deadlock can occur when transactions lock rows in multiple tables (through statements such as UPDATE or SELECT. I have 8 queue workers running on my server. My queues are bit different than normally what it is used for. I just want to get rid of MySQL deadlocks with laravel queues.
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