cache-size-bytes usable?

[Hanno Schlichting-4]

Hi.

I've been playing around with the new "cache-size-bytes" setting to
limit the ZODB cache sizes.

My ZODB 3.9.3 (Zope 2.12 / Plone) config had a setting of
cache-size-bytes to 128mb and a cache-size of one million (to
effectively disable the object number based checks). This was without
ZEO, a simple FileStorage with a blobstorage enabled.

When using and testing this for a while in a setup with two database
connection threads, things worked fine for a while, but after 10 to 15
minutes of various load patterns things broke down. Both connections
started to minimize their connection cache down to zero objects
continuously.

It looks like the active cache size isn't properly reduced at some
point and as a result the cache thinks it is already using the maximum
amount.

Has anyone used the bytes limited cache in production yet and has any
experience with it?

I can try to isolate the problem some more. Playing around I did
everything from loading objects, packing the database, minimizing
caches, so it's hard to know what might cause this.

Thanks,
Hanno
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[Andreas Jung-5]

Am 07.11.09 18:25, schrieb Hanno Schlichting:

> Hi.
>
> I've been playing around with the new "cache-size-bytes" setting to
> limit the ZODB cache sizes.
>
> My ZODB 3.9.3 (Zope 2.12 / Plone) config had a setting of
> cache-size-bytes to 128mb and a cache-size of one million (to
> effectively disable the object number based checks). This was without
> ZEO, a simple FileStorage with a blobstorage enabled.
>
> When using and testing this for a while in a setup with two database
> connection threads, things worked fine for a while, but after 10 to 15
> minutes of various load patterns things broke down. Both connections
> started to minimize their connection cache down to zero objects
> continuously.
>
> It looks like the active cache size isn't properly reduced at some
> point and as a result the cache thinks it is already using the maximum
> amount.
>
> Has anyone used the bytes limited cache in production yet and has any
> experience with it?
>
> I can try to isolate the problem some more. Playing around I did
> everything from loading objects, packing the database, minimizing
> caches, so it's hard to know what might cause this.

I would assume that this feature is working since it comes
from the Haufe Zope fork afaik and likely we are using it in production.
But I have to check this by digging through the legacy of the
origin author.

Andreas

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[Hanno Schlichting-4]

On Sat, Nov 7, 2009 at 6:34 PM, Andreas Jung <lists@...> wrote:
> Am 07.11.09 18:25, schrieb Hanno Schlichting:
>> Has anyone used the bytes limited cache in production yet and has any
>> experience with it?
>
> I would assume that this feature is working since it comes
> from the Haufe Zope fork afaik and likely we are using it in production.
> But I have to check this by digging through the legacy of the
> origin author.

Well, I know Jim had to fix a number of bugs already after Dieter's
initial patch landed in the codebase. Like "Sizes of new objects
weren't added to the object cache size estimation" sometime late in
the 3.9.0 process.

So the codebase isn't really the same and there have been a huge
number of changes in the ZODB codebase compared to what the Haufe Zope
fork was based on. That's why I'd be interested to know if someone
uses the actual ZODB 3.9.x codebase.

Hanno
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