[Zope-dev] [ZODB-Dev] [announce] NEO 1.0 - scalable and redundant storage for ZODB

[Marius Gedminas]

On Tue, Aug 28, 2012 at 06:31:05PM +0200, Vincent Pelletier wrote:
> On Tue, 28 Aug 2012 16:31:20 +0200,
> Martijn Pieters <mj at zopatista.com> wrote :
> > Anything else different? Did you make any performance comparisons
> > between RelStorage and NEO?
> 
> I believe the main difference compared to all other ZODB Storage
> implementation is the finer-grained locking scheme: in all storage
> implementations I know, there is a database-level lock during the
> entire second phase of 2PC, whereas in NEO transactions are serialised
> only when they alter a common set of objects.

This could be a compelling point.  I've seen deadlocks in an app that
tried to use both ZEO and PostgreSQL via the Storm ORM.  (The thread
holding the ZEO commit lock was blocked waiting for the PostgreSQL
commit to finish, while the PostgreSQL server was waiting for some other
transaction to either commit or abort -- and that other transaction
couldn't proceed because it was waiting for the ZEO lock.)

Marius Gedminas
-- 
People who think, "Oh this is a one-off," need to be offed, or perhaps politely
removed from the project.
        -- George Neville-Neil
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