Serialization failure: 1213 Deadlock found when trying to get lock; try restarting transaction

[Dante Lorenso]

All,

I am trying to create an atomic operation in MySQL that will manage a
"queue". I want to lock an item from a table for exclusive access by one of
my processing threads. I do this by inserting the unique ID of the record I
want to reserve into my "cli_lock" table. The following query is what I am
using to lock a record in my queue:

INSERT INTO cli_lock (lock_id, object_id, lock_type, expire_dt)
SELECT $LOCK_ID, q.queue_id, 'parse', DATE_ADD(NOW(), INTERVAL 1 HOUR)
FROM queue q
LEFT JOIN cli_lock l ON l.object_id = q.queue_id AND l.lock_type = 'parse'
WHERE l.object_id IS NULL
AND q.status = 'parse'
ORDER BY q.file_size ASC, q.created ASC, q.queue_id ASC
LIMIT 1

However, as I execute this query several times each minute from different
applications, I frequently get these messages:

DB ERROR: SQLSTATE[40001]: Serialization failure: 1213 Deadlock found when
trying to get lock; try restarting transaction

Am I writing my query wrong or expecting behavior that MySQL doesn't
support?

-- Dante

[Michael Dykman]

The query is probably fine.. that is just the lock doing it's job.
Take that advice literally.. when you fail with that class of
exception, delay a milli-second or two and retry. For a large PHP
site I designed, we had that behaviour built-in: up to three attempts
waits 5, then 10 ms between trys. In spite of 1M+ user/day we rarely
made it to the third attempt.

- michael dykman

Post by Dante Lorenso
All,
I am trying to create an atomic operation in MySQL that will manage a
"queue".  I want to lock an item from a table for exclusive access by one of
my processing threads.  I do this by inserting the unique ID of the record I
want to reserve into my "cli_lock" table.  The following query is what I am
INSERT INTO cli_lock (lock_id, object_id, lock_type, expire_dt)
SELECT $LOCK_ID, q.queue_id, 'parse', DATE_ADD(NOW(), INTERVAL 1 HOUR)
FROM queue q
 LEFT JOIN cli_lock l ON l.object_id = q.queue_id AND l.lock_type = 'parse'
WHERE l.object_id IS NULL
 AND q.status = 'parse'
ORDER BY q.file_size ASC, q.created ASC, q.queue_id ASC
LIMIT 1
However, as I execute this query several times each minute from different
DB ERROR: SQLSTATE[40001]: Serialization failure: 1213 Deadlock found when
trying to get lock; try restarting transaction
Am I writing my query wrong or expecting behavior that MySQL doesn't
support?
-- Dante

--
- michael dykman
- ***@gmail.com

May the Source be with you.

[Johan De Meersman]

First things first: You *are* on InnoDB, which has row-level locking instead
of table-level ?

Post by Michael Dykman
The query is probably fine.. that is just the lock doing it's job.
Take that advice literally.. when you fail with that class of
exception, delay a milli-second or two and retry. For a large PHP
site I designed, we had that behaviour built-in: up to three attempts
waits 5, then 10 ms between trys. In spite of 1M+ user/day we rarely
made it to the third attempt.
- michael dykman

Post by Dante Lorenso
All,
I am trying to create an atomic operation in MySQL that will manage a
"queue". I want to lock an item from a table for exclusive access by one

of

Post by Dante Lorenso
my processing threads. I do this by inserting the unique ID of the

record I

Post by Dante Lorenso
want to reserve into my "cli_lock" table. The following query is what I

am

Post by Dante Lorenso
INSERT INTO cli_lock (lock_id, object_id, lock_type, expire_dt)
SELECT $LOCK_ID, q.queue_id, 'parse', DATE_ADD(NOW(), INTERVAL 1 HOUR)
FROM queue q
LEFT JOIN cli_lock l ON l.object_id = q.queue_id AND l.lock_type =

'parse'

Post by Dante Lorenso
WHERE l.object_id IS NULL
AND q.status = 'parse'
ORDER BY q.file_size ASC, q.created ASC, q.queue_id ASC
LIMIT 1
However, as I execute this query several times each minute from different
DB ERROR: SQLSTATE[40001]: Serialization failure: 1213 Deadlock found

when

Post by Dante Lorenso
trying to get lock; try restarting transaction
Am I writing my query wrong or expecting behavior that MySQL doesn't
support?
-- Dante

--
- michael dykman
May the Source be with you.
--
MySQL General Mailing List
For list archives: http://lists.mysql.com/mysql

[D. Dante Lorenso]

Post by Johan De Meersman
First things first: You *are* on InnoDB, which has row-level locking
instead of table-level ?

Yes, both "cli_lock" and "queue" tables are InnoDB. The server is
running MySQL 5.1.36.

I find it strange that I would have so many of these deadlocks
throughout a day when these queries run from 3 processes every 20
seconds. What's the chance that 2 scripts should be executing these
queries simultaneously, and even if the probability exists, why is it
causing this deadlock error each time?

If I break the query into 2 parts ... like SELECT FOR UPDATE followed by
the INSERT/UPDATE, would that help fix the errors?

What is this error exactly, anyhow? Where is the deadlock ... is it on
the select or the insert?

-- Dante

Post by Johan De Meersman
The query is probably fine.. that is just the lock doing it's job.
Take that advice literally.. when you fail with that class of
exception, delay a milli-second or two and retry. For a large PHP
site I designed, we had that behaviour built-in: up to three attempts
waits 5, then 10 ms between trys. In spite of 1M+ user/day we rarely
made it to the third attempt.
- michael dykman

Post by Dante Lorenso
All,
I am trying to create an atomic operation in MySQL that will manage a
"queue". I want to lock an item from a table for exclusive

access by one of

Post by Dante Lorenso
my processing threads. I do this by inserting the unique ID of

the record I

Post by Dante Lorenso
want to reserve into my "cli_lock" table. The following query is

what I am

Post by Dante Lorenso
INSERT INTO cli_lock (lock_id, object_id, lock_type, expire_dt)
SELECT $LOCK_ID, q.queue_id, 'parse', DATE_ADD(NOW(), INTERVAL 1

HOUR)

Post by Dante Lorenso
FROM queue q
LEFT JOIN cli_lock l ON l.object_id = q.queue_id AND l.lock_type

= 'parse'

Post by Dante Lorenso
WHERE l.object_id IS NULL
AND q.status = 'parse'
ORDER BY q.file_size ASC, q.created ASC, q.queue_id ASC
LIMIT 1
However, as I execute this query several times each minute from

different

Post by Dante Lorenso
DB ERROR: SQLSTATE[40001]: Serialization failure: 1213 Deadlock

found when

Post by Dante Lorenso
trying to get lock; try restarting transaction
Am I writing my query wrong or expecting behavior that MySQL doesn't
support?
-- Dante

--
----------
D. Dante Lorenso
***@lorenso.com
972-333-4139

[D. Dante Lorenso]

Post by Michael Dykman
The query is probably fine.. that is just the lock doing it's job.
Take that advice literally.. when you fail with that class of
exception, delay a milli-second or two and retry. For a large PHP
site I designed, we had that behaviour built-in: up to three attempts
waits 5, then 10 ms between trys. In spite of 1M+ user/day we rarely
made it to the third attempt.

Sounds like the answer is "that's just the way MySQL is". I don't
usually like those kinds of answers. I've written similar queries in
another DB and never got these types of errors. Perhaps there is a
better way to create a "queue" system that avoids this problem entirely?
I feel like if MySQL is throwing out this "wanring" to me, that I
should be doing to correct it.

I have a queue with several states in it:

state1 ---> processing1 --> state2 ---> processing2 ---> state3

I want to find a record that is in state1 and reserve the right to
process it. After it is done being processed, the code will set it's
state to state2 which allows the next application to pick it up and work
on it. I am actually using PHP/MySQL and this problem sounds like a job
for a message queue. So, in essence, my solution is like a message
queue built using MySQL tables to store and manage the queue.

Has this problem already been solved in a way I can just leverage the
existing solution? ... er, without the deadlock issue.

Are you saying I should just ignore the message about deadlock and let
the app run as if the message never occurred (since there's not a
problem with seeing that message)?

-- Dante

Post by Michael Dykman
- michael dykman

Post by Dante Lorenso
All,
I am trying to create an atomic operation in MySQL that will manage a
"queue". I want to lock an item from a table for exclusive access by one of
my processing threads. I do this by inserting the unique ID of the record I
want to reserve into my "cli_lock" table. The following query is what I am
INSERT INTO cli_lock (lock_id, object_id, lock_type, expire_dt)
SELECT $LOCK_ID, q.queue_id, 'parse', DATE_ADD(NOW(), INTERVAL 1 HOUR)
FROM queue q
LEFT JOIN cli_lock l ON l.object_id = q.queue_id AND l.lock_type = 'parse'
WHERE l.object_id IS NULL
AND q.status = 'parse'
ORDER BY q.file_size ASC, q.created ASC, q.queue_id ASC
LIMIT 1
However, as I execute this query several times each minute from different
DB ERROR: SQLSTATE[40001]: Serialization failure: 1213 Deadlock found when
trying to get lock; try restarting transaction
Am I writing my query wrong or expecting behavior that MySQL doesn't
support?

[Michael Dykman]

The "SELECT FOR UPDATE" is supposed to lock those rows selected.. an
operation in another connection attempting to read or modify those
rows gets an error on the lock if it is still in place. That is that
SELECT FOR UPDATE is supposed to do.

If that is not the behaviour you want, then why are you using the lock?

- michael dykman

The query is probably fine..  that is just the lock doing it's job.
Take that advice literally..  when you fail with that class of
exception, delay a milli-second or two and retry.  For a large PHP
site I designed, we had that behaviour built-in: up to three attempts
waits 5, then 10 ms between trys.  In spite of 1M+ user/day we rarely
made it to the third attempt.

Sounds like the answer is "that's just the way MySQL is".  I don't usually
like those kinds of answers.  I've written similar queries in another DB and
never got these types of errors.  Perhaps there is a better way to create a
"queue" system that avoids this problem entirely?  I feel like if MySQL is
throwing out this "wanring" to me, that I should be doing to correct it.
   state1 ---> processing1 --> state2 ---> processing2 ---> state3
I want to find a record that is in state1 and reserve the right to process
it.  After it is done being processed, the code will set it's state to
state2 which allows the next application to pick it up and work on it.  I am
actually using PHP/MySQL and this problem sounds like a job for a message
queue.  So, in essence, my solution is like a message queue built using
MySQL tables to store and manage the queue.
Has this problem already been solved in a way I can just leverage the
existing solution? ... er, without the deadlock issue.
Are you saying I should just ignore the message about deadlock and let the
app run as if the message never occurred (since there's not a problem with
seeing that message)?
-- Dante

 - michael dykman

Post by Dante Lorenso
All,
I am trying to create an atomic operation in MySQL that will manage a
"queue".  I want to lock an item from a table for exclusive access by one of
my processing threads.  I do this by inserting the unique ID of the record I
want to reserve into my "cli_lock" table.  The following query is what I am
INSERT INTO cli_lock (lock_id, object_id, lock_type, expire_dt)
SELECT $LOCK_ID, q.queue_id, 'parse', DATE_ADD(NOW(), INTERVAL 1 HOUR)
FROM queue q
 LEFT JOIN cli_lock l ON l.object_id = q.queue_id AND l.lock_type = 'parse'
WHERE l.object_id IS NULL
 AND q.status = 'parse'
ORDER BY q.file_size ASC, q.created ASC, q.queue_id ASC
LIMIT 1
However, as I execute this query several times each minute from different
DB ERROR: SQLSTATE[40001]: Serialization failure: 1213 Deadlock found when
trying to get lock; try restarting transaction
Am I writing my query wrong or expecting behavior that MySQL doesn't
support?

--
- michael dykman
- ***@gmail.com

May the Source be with you.

[Jesper Wisborg Krogh]

Try to run

SHOW ENGINE INNODB STATUS;

Near the top there will be some information on the latest deadlock.
That might help you to understand what is deadlocking. Sometimes
changing the query or changing the indexes can remove the condition
that causes the deadlock. I don't know whether you have triggers on
any of your tables? If so that's one place to watch for as well as
the deadlock will show up as it is on the original query even if it
is a trigger causing it.

Jesper

Post by Michael Dykman
The "SELECT FOR UPDATE" is supposed to lock those rows selected.. an
operation in another connection attempting to read or modify those
rows gets an error on the lock if it is still in place. That is that
SELECT FOR UPDATE is supposed to do.
If that is not the behaviour you want, then why are you using the lock?
- michael dykman
On Mon, Feb 1, 2010 at 12:29 PM, D. Dante Lorenso

Post by D. Dante Lorenso

Post by Michael Dykman
The query is probably fine.. that is just the lock doing it's job.
Take that advice literally.. when you fail with that class of
exception, delay a milli-second or two and retry. For a large PHP
site I designed, we had that behaviour built-in: up to three
attempts
waits 5, then 10 ms between trys. In spite of 1M+ user/day we rarely
made it to the third attempt.

Sounds like the answer is "that's just the way MySQL is". I don't
usually
like those kinds of answers. I've written similar queries in
another DB and
never got these types of errors. Perhaps there is a better way to
create a
"queue" system that avoids this problem entirely? I feel like if
MySQL is
throwing out this "wanring" to me, that I should be doing to
correct it.
state1 ---> processing1 --> state2 ---> processing2 ---> state3
I want to find a record that is in state1 and reserve the right to process
it. After it is done being processed, the code will set it's
state to
state2 which allows the next application to pick it up and work on
it. I am
actually using PHP/MySQL and this problem sounds like a job for a message
queue. So, in essence, my solution is like a message queue built
using
MySQL tables to store and manage the queue.
Has this problem already been solved in a way I can just leverage the
existing solution? ... er, without the deadlock issue.
Are you saying I should just ignore the message about deadlock and let the
app run as if the message never occurred (since there's not a
problem with
seeing that message)?
-- Dante

Post by Michael Dykman
- michael dykman

Post by Dante Lorenso
All,
I am trying to create an atomic operation in MySQL that will manage a
"queue". I want to lock an item from a table for exclusive
access by one
of
my processing threads. I do this by inserting the unique ID of the record I
want to reserve into my "cli_lock" table. The following query
is what I
am
INSERT INTO cli_lock (lock_id, object_id, lock_type, expire_dt)
SELECT $LOCK_ID, q.queue_id, 'parse', DATE_ADD(NOW(), INTERVAL 1 HOUR)
FROM queue q
LEFT JOIN cli_lock l ON l.object_id = q.queue_id AND l.lock_type = 'parse'
WHERE l.object_id IS NULL
AND q.status = 'parse'
ORDER BY q.file_size ASC, q.created ASC, q.queue_id ASC
LIMIT 1
However, as I execute this query several times each minute from different
DB ERROR: SQLSTATE[40001]: Serialization failure: 1213 Deadlock
found
when
trying to get lock; try restarting transaction
Am I writing my query wrong or expecting behavior that MySQL doesn't
support?

--
- michael dykman
May the Source be with you.
--
MySQL General Mailing List
For list archives: http://lists.mysql.com/mysql
To unsubscribe: http://lists.mysql.com/mysql?

[Madonna DeVaudreuil]

May I suggest this link? I found it useful. I haven't looked but there
may be more recent posts with additional information.

http://www.xaprb.com/blog/2007/09/18/how-to-debug-innodb-lock-waits/

Donna




From:
Jesper Wisborg Krogh <***@noggin.com.au>
To:
***@lists.mysql.com
Date:
02/01/2010 03:43 PM
Subject:
Re: Serialization failure: 1213 Deadlock found when trying to get lock;
try restarting transaction



Try to run

SHOW ENGINE INNODB STATUS;

Near the top there will be some information on the latest deadlock.
That might help you to understand what is deadlocking. Sometimes
changing the query or changing the indexes can remove the condition
that causes the deadlock. I don't know whether you have triggers on
any of your tables? If so that's one place to watch for as well as
the deadlock will show up as it is on the original query even if it
is a trigger causing it.

Jesper

Post by Michael Dykman
The "SELECT FOR UPDATE" is supposed to lock those rows selected.. an
operation in another connection attempting to read or modify those
rows gets an error on the lock if it is still in place. That is that
SELECT FOR UPDATE is supposed to do.
If that is not the behaviour you want, then why are you using the lock?
- michael dykman
On Mon, Feb 1, 2010 at 12:29 PM, D. Dante Lorenso

Post by D. Dante Lorenso

Post by Michael Dykman
The query is probably fine.. that is just the lock doing it's job.
Take that advice literally.. when you fail with that class of
exception, delay a milli-second or two and retry. For a large PHP
site I designed, we had that behaviour built-in: up to three
attempts
waits 5, then 10 ms between trys. In spite of 1M+ user/day we rarely
made it to the third attempt.

Sounds like the answer is "that's just the way MySQL is". I don't
usually
like those kinds of answers. I've written similar queries in
another DB and
never got these types of errors. Perhaps there is a better way to
create a
"queue" system that avoids this problem entirely? I feel like if
MySQL is
throwing out this "wanring" to me, that I should be doing to
correct it.
state1 ---> processing1 --> state2 ---> processing2 ---> state3
I want to find a record that is in state1 and reserve the right to process
it. After it is done being processed, the code will set it's
state to
state2 which allows the next application to pick it up and work on
it. I am
actually using PHP/MySQL and this problem sounds like a job for a message
queue. So, in essence, my solution is like a message queue built
using
MySQL tables to store and manage the queue.
Has this problem already been solved in a way I can just leverage the
existing solution? ... er, without the deadlock issue.
Are you saying I should just ignore the message about deadlock and let the
app run as if the message never occurred (since there's not a
problem with
seeing that message)?
-- Dante

Post by Michael Dykman
- michael dykman

Post by Dante Lorenso
All,
I am trying to create an atomic operation in MySQL that will manage a
"queue". I want to lock an item from a table for exclusive
access by one
of
my processing threads. I do this by inserting the unique ID of the record I
want to reserve into my "cli_lock" table. The following query
is what I
am
INSERT INTO cli_lock (lock_id, object_id, lock_type, expire_dt)
SELECT $LOCK_ID, q.queue_id, 'parse', DATE_ADD(NOW(), INTERVAL 1 HOUR)
FROM queue q
LEFT JOIN cli_lock l ON l.object_id = q.queue_id AND l.lock_type = 'parse'
WHERE l.object_id IS NULL
AND q.status = 'parse'
ORDER BY q.file_size ASC, q.created ASC, q.queue_id ASC
LIMIT 1
However, as I execute this query several times each minute from different
DB ERROR: SQLSTATE[40001]: Serialization failure: 1213 Deadlock
found
when
trying to get lock; try restarting transaction
Am I writing my query wrong or expecting behavior that MySQL doesn't
support?

--
- michael dykman
May the Source be with you.
--
MySQL General Mailing List
For list archives: http://lists.mysql.com/mysql
To unsubscribe: http://lists.mysql.com/mysql?

--
MySQL General Mailing List
For list archives: http://lists.mysql.com/mysql
To unsubscribe:
http://lists.mysql.com/mysql?unsub=***@sironahealth.com