[ZODB-Dev] RelStorage MySQL - StorageError: Unable to acquire commit lock

[Rudá Porto Filgueiras]

I begin to use RelStorage in a production site with Plone 2.5.
Everything was running without failures since 01 august 2009.
But today after a failure in tpc_abort, all instances conneceted to
MySQL can't acquire commit lock.

Follow tpc_abort traceback:

2009-08-12T14:12:08 ERROR txn.1115806016 Error in tpc_abort() on
manager <MultiObjectResourceAdapter for <ZODB.DB.TransactionalUndo
object at 0x210f6790> at 654293328>
Traceback (most recent call last):
  File "/usr/local/zope/agecom-virtual/eggs/ZODB3-3.7.3_polling-py2.4-linux-x86_64.egg/transaction/_transaction.py",
line 533, in _cleanup
    rm.tpc_abort(self)
  File "/usr/local/zope/agecom-virtual/eggs/ZODB3-3.7.3_polling-py2.4-linux-x86_64.egg/transaction/_transaction.py",
line 628, in tpc_abort
    self.manager.tpc_abort(txn)
  File "/usr/local/zope/agecom-virtual/eggs/ZODB3-3.7.3_polling-py2.4-linux-x86_64.egg/ZODB/BaseStorage.py",
line 194, in tpc_abort
    self._abort()
  File "/usr/local/zope/agecom-virtual/eggs/RelStorage-1.2.0b2-py2.4.egg/relstorage/relstorage.py",
line 710, in _abort
    self._rollback_load_connection()
  File "/usr/local/zope/agecom-virtual/eggs/RelStorage-1.2.0b2-py2.4.egg/relstorage/relstorage.py",
line 166, in _rollback_load_connection
    self._load_conn.rollback()
OperationalError: (2006, 'MySQL server has gone away')

And after, all instances report this exeption:

2009-08-12T14:21:53 ERROR Zope.SiteErrorLog
http://adm.agecom.ba.gov.br/login_form
Traceback (innermost last):
  Module ZPublisher.Publish, line 121, in publish
  Module Zope2.App.startup, line 240, in commit
  Module transaction._manager, line 96, in commit
  Module transaction._transaction, line 395, in commit
  Module transaction._transaction, line 498, in _commitResources
  Module ZODB.Connection, line 730, in tpc_vote
  Module relstorage.relstorage, line 675, in tpc_vote
  Module relstorage.relstorage, line 659, in _vote
  Module relstorage.relstorage, line 566, in _prepare_tid
  Module relstorage.adapters.mysql, line 506, in start_commit
  Module relstorage.adapters.mysql, line 672, in _hold_commit_lock
StorageError: Unable to acquire commit lock

I solve the problem restarting all instances, and the site became
operational again, but I have some questions:

This can be a bug or there is any problem in my enviroment/application?
There is another solution to release commit lock without restart all instances?

Cheers,

-- 
Rudá Porto Filgueiras
http://python-blog.blogspot.com