DuaneCompton

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Trying to add 2 nodes simultaneously to closure_tree table results in a deadlock

Can confirm, this issue has been around for a while. 6.2 seems to have increased the frequency from a monthly to hourly occurrence. Ruby 2.3.1 Rails 4.2.7.1 Closure tree 6.2...

Trying to add 2 nodes simultaneously to closure_tree table results in a deadlock

I am killing the lock by hand. SELECT * FROM pg_locks; SELECT pg_terminate_backend(\'\') the lock does not respond to a pg_kill_backend when in this state. I am downgraded to 6.1....

Trying to add 2 nodes simultaneously to closure_tree table results in a deadlock

@mceachen There are 6 threads running that are simultaneously under load. under v6.1 I am averaging 1 lockup/10k inserts. In v6.2 it locks basically immediately. Might be two separate issues...

Trying to add 2 nodes simultaneously to closure_tree table results in a deadlock

@mceachen Anything I can do from a bug gathering standpoint to help troubleshoot this issue? We still run into a lock up on a weekly basis on 6.0. I am...

Trying to add 2 nodes simultaneously to closure_tree table results in a deadlock

@mceachen will do.

Trying to add 2 nodes simultaneously to closure_tree table results in a deadlock

@mceachen So, I've noticed when we hit this state there is really just one lock that is hanging around. Is there any reason you could see that we couldn't use...

Trying to add 2 nodes simultaneously to closure_tree table results in a deadlock

So, its not a dead lock per se. If I move around the locking obtain/release in just the critical sections of the write/delete/children call then it will be detected as...

Trying to add 2 nodes simultaneously to closure_tree table results in a deadlock

Sorry, its not a deadlock in the traditional sense, its actually worse since a deadlock will be detected and aborted. In this case, the first process has obtained the lock...

Trying to add 2 nodes simultaneously to closure_tree table results in a deadlock

Thank you. I will see what I can do as well. I do not believe at this time that its an a/b b/a situation, because I think the lock acquisition...

Trying to add 2 nodes simultaneously to closure_tree table results in a deadlock

@mceachen It appears the issue I am running into is specifically (and I am guessing amitsaxena as well) around the numeric reordering (https://github.com/mceachen/closure_tree/blob/master/lib/closure_tree/hierarchy_maintenance.rb#L76) when calling add_child. Writer 1 will hang...