[Postgres-xl-developers] pgxl dead lock because of ddl cmd running sequence

Mason Sharp msharp at translattice.com
Fri Dec 5 07:30:52 PST 2014

On Wed, Nov 26, 2014 at 2:36 AM, Jov <amutu at amutu.com> wrote:

> dead lock repeat step:
> 1.setup a pgxl cluster with 4 nodes:co1,co2,dn1,dn2.
> 2.running pgbench with 72 clients on co1,with select,insert,delete query
> for a table xx
> 3.running a ddl on co2,for example:alter table xx add check...
> Now,the cluter will lock up.After inspect the pg_stat_activity and
> pg_locks on each node,I find the ddl and dml produce dead lock.
> on co2,the alter table stmt shows active and waiting the remote node
> return.
> on dn1 and dn2,the alter table stmt are in idle in tx statment,while there
> are some remote plan running with waiting stat which I think is the dml
> stmt waiting for the alter table to release the x-lock.
> on co1 the alter table stmt in waiting state and waiting x-lock for the
> table.the lock hold by some select stmt,which are in active state.
> after reading the code,I find that the ddl stmt will be send to the dn
> node ,then the co node,I think this is the problem.
> So Why pgxl not running ddl on all co first,then dn?
I am not sure that would help with the deadlock case. I think the original
idea here was to try to get the appropriate locks when concurrent DML
occurring.  Please allow us more time to investigate.

Can you please add this case here:




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Mason Sharp

TransLattice - http://www.translattice.com
Clustered and Distributed Database Solutions
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