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Re: Abort transaction when detecting lock
Posted by: Rick James
Date: August 14, 2016 06:17PM

I don't think you can directly do what you propose.

* Deadlocks are immediately recognized and one transaction is rolled back.
* If you are processing multiple items, do them in some predictable order (eg, sort them). This will cut back on deadlocks, but may lead to timeouts.
* Having a transaction run longer than a few seconds is a no-no.
* If you are hitting innodb_lock_wait_timeout, your transaction need rethinking.

It sounds like you have two of those issues... "N records to update and the update incurs some work and N is big"

Let's look at other ways to "fix" the problem.

* "The update incurs some work". Can some of the work be done before STARTing the TRANSACTION? (Even if it is thrown away sometimes, this may help speed up the transaction.)

* Why is N "big"? Could you get the desired transactional integrity with smaller N?

* Might it be better to completely lock out one thread while another thread is working? That would involve something other than what you currently have involved in the transaction. A complet lockout would probably make the xaction run faster, and would avoid deadlocks and timeouts.

Run an experiment -- see how long a xaction takes when there is no competition from other threads. Then see how long it takes if multiple threads are competing.

I realize I am doing a lot of handwaving. But so are you. Would you care to be more explicit?

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Written By
August 09, 2016 03:16AM
Re: Abort transaction when detecting lock
August 14, 2016 06:17PM

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