[Zope] Preventing Zope Spinning?

[Jens Vagelpohl]

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Persistent caches can introduce odd errors, unfortunately. They can  
create inconsistencies between what a ZEO client thinks the database  
state is and what the ZEO server thinks. Not recommended for  
production setups.

jens


On 25 May 2006, at 15:56, Jonathan wrote:

> How about setting up persistent caches for your zeo clients, so  
> that when the zeo server goes down you save some cache-reloading  
> time when it restarts?
>
>
> Jonathan
>
>
> ----- Original Message ----- From: "Brian Brinegar"  
> <brinegar at ecn.purdue.edu>
> To: <zope at zope.org>
> Cc: "David S Carmichael" <carmicha at ecn.purdue.edu>; "Andrew T  
> Sydelko" <sydelko at ecn.purdue.edu>; "Christopher N Deckard"  
> <cnd at ecn.purdue.edu>
> Sent: Thursday, May 25, 2006 10:49 AM
> Subject: [Zope] Preventing Zope Spinning?
>
>
>> The majority of the Purdue University Engineering web presence is
>> provided via a cluster running ZEO. We offer hosting for every  
>> school,
>> department, faculty, staff, and student in the College. Because of  
>> this
>> we have a large number of content maintainers/developers on our  
>> system.
>> We are running into problems with users writing bad code which  
>> spins or
>> uploading huge files which seems to tie up the database for long  
>> periods
>> of time.
>>
>> We end up in a situation where something will spin a client and a  
>> user
>> will repeatedly resubmit the request until all of our zeo clients are
>> spinning. Our clients are eventually killed, usually manually, and
>> quickly come back up. We drop the zeo cache on a restart to improve
>> startup speed, so when the clients do come back up we have 100% cache
>> misses and the zeo server gets pounded resulting in slow performance
>> until the client caches repopulate.
>>
>> Occasionally we can track down the offending URL and correct the
>> problem, sometimes we cannot.
>>
>> Perhaps these issues will be addressed in future versions of Zope, we
>> are currently running Zope 2.6.4
>>
>> What I would like is some sort of timeout for requests, however I  
>> do not
>> want to punish users with slow connections. Perhaps a way to kill  
>> off a
>> specific request that is consuming excessive resources, without  
>> killing
>> the entire client.
>>
>> Below is some information on our setup:
>>
>> 1 zeo server (Solaris)
>>  - 82 gig datafs
>>  - transaction time out of 120 seconds
>>
>> 2 load balanced zeoclients (Linux)
>>  - 2 gig zeo cache
>>  - Database Cache 30000 objects
>>  - 4 threads
>>
>> 2 failover apaches (Linux)
>>  - using pydirector for load balancing
>>
>> We are receiving appoximately 1 million hits per day, which from what
>> I've read is not all that much. We probably have a higher number  
>> of DB
>> writes than usual because of the number of developers/maintainers.  
>> Can
>> anyone make suggestions for providing a more stable environment?
>>
>> Thank you,
>> Brian Brinegar
>> Web Systems Developer
>> Engineering Computer Network
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>
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