Re: [ZODB-Dev] [Enhancement Proposal] Garanteed lifetime for volatile variables

[Dieter Maurer]

Jim Fulton wrote at 2006-10-9 15:04 -0400:
 ...
 To make cache garbage collection as fast as possible,
 I have proposed to actually store the sticky information in the
 C object structure.

I don't like the idea of adding that overhead to every
persistent object just for this use case.  OTOH, we only
need a bit and I think we had a few spare bits.  So maybe
this wouldn't require any new space.

That's how I implemented it in our local Zope copy.

#define cPersistent_HEAD \
PyObject_HEAD \
PyObject *jar; \
PyObject *oid; \
PerCache *cache; \
CPersistentRing ring; \
char serial[8]; \
signed char state; \
/* DM 2005-08-22: sticky support */ \
/* unsigned char reserved[3]; */ \
unsigned char sticky; /* we need only a bit; but byte access is cheaper */\
unsigned char reserved[2];

As you can see, I used one of the three reserved chars -- and did not
increase the size of persistent objects.


-- 
Dieter
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[ZODB-Dev] Anybody using ZODB with no calls to fsync in production?

[Roché Compaan]

Has anybody been using Zope with a ZODB patched to not call fsync since
the fsync thread in July 2004:

http://mail.zope.org/pipermail/zodb-dev/2004-July/007682.html

I just took Tim Peters' timefsync.py for a spin on some of our servers
and got transaction rates from 4 to 10 times faster, compared to running
ZODB with a call to fsync.

I'm tempted to deploy ZODB without fsync on some production FileStorage
instances. Will I regret it?

-- 
Roché Compaan
Upfront Systems   http://www.upfrontsystems.co.za

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