[ZODB-Dev] Debugging ConflictErrors

[Casey Duncan]

On Thu, 15 Jan 2004 14:47:21 +0100
Thomas Güttler <tguettler at tbz-pariv.de> wrote:

> Hi!
> 
> Has someone hints how to debug ConflictErrors?
> 
> Up to now I log ConflictErrors like this:
> 
>         # First version taken from Dulcinea/lib/ui/publish.py
>         retries=15
>         for i in range(retries):
>             try:
>                 return Publisher.try_publish(self, request, path)
>             except ConflictError, exc:
>                 obj=self.root_namespace._p_jar[exc.oid]
>                 print "ConflictError %sv%s: retrying request. " \
>                       "path=%s user=%s obj=%s oid=%s" % (
>                     i, retries,
>                     path, os.environ.get("REMOTE_USER", ""),
>                     repr(exc.oid), obj)
>                 get_transaction().abort()
>                 request.response = HTTPResponse() # reset response
>                 object time.sleep(2 + (random.random() * (i+1)))
>         else:
>             raise RuntimeError("too many conflict errors")
> 
> The conflicts always are in my root object. This is
> the object which holds all other objects. I use ZODB 3.2

Do you regularly mutate the root object (i.e., add and remove keys?). If
so I would recommend against it, AFAIK it will not allow concurrent
changes without conflicts. If you need to mutate a mapping concurrently
you should use a BTree hung off the root object.

In general ZODB apps keep a few static keys in the root and only mutate
lower objects regularly.

-Casey