Re: ZODB eating CPU but RAM is free

Jim Fulton <[email protected]> Wed, 19 Jul 2017 10:53:44 -0600
Newsgroups gmane.comp.web.zope.zodb
Message-ID <CAPDm-FjJu0Hirb5hDevj0hcuoT4T_PAwteecLOC1GNPM4xBHdg@mail.gmail.com>
On Wed, Jul 19, 2017 at 7:28 AM, Hanno Schlichting <[email protected]>
wrote:

> On Wed, Jul 19, 2017, at 14:53, Joni Orponen wrote:
>
> On Wed, Jul 19, 2017 at 2:42 PM, Hanno Schlichting <[email protected]>
> wrote:
>
>
> Try increasing the zodb-cache-size for the zope2instance (client1). It
> defaults to 30000, try increasing it to 100000 and monitor the RAM usage.
>
>
> Is the cache_size_bytes option still considered to be experimental and/or
> broken?
>
>
> I'd still consider it to be experimental. I did my last tests with it 8 or
> so years ago and it didn't work reliably back than.
>

How so?

One thing to understand is that ZODB doesn't limit memory usage.
Ghostifies objects to meet memory settings at certain times like
transaction boundaries and when asked to explicitly.  So a transaction that
loads a lot of objects can grow ram without bound.  This is why
applications that load *lots* of objects should explicitly reduce cache
size by calling _p_jar.cacheGC() occasionally.

Jim

-- 
Jim Fulton
http://jimfulton.info

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