On 07/09/2014 05:17 AM, Ihar Hrachyshka wrote:
Hash: SHA512

Hi all,

Multiple projects are suffering from db lock timeouts due to deadlocks
deep in mysqldb library that we use to interact with mysql servers. In
essence, the problem is due to missing eventlet support in mysqldb
module, meaning when a db lock is encountered, the library does not
yield to the next green thread, allowing other threads to eventually
unlock the grabbed lock, and instead it just blocks the main thread,
that eventually raises timeout exception (OperationalError).

The failed operation is not retried, leaving failing request not
served. In Nova, there is a special retry mechanism for deadlocks,
though I think it's more a hack than a proper fix.

This may be a bit of a tangent to the original discussion, but does anyone know where we stand with postgres and eventlets? Is pyscopg2 susceptible to the same problems as mysqldb?


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