[Erp5-dev] expand method performance, ZEO questions

[Yoshinori Okuji]

Hello,

On Thursday 20 December 2007 12:18, Łukasz Nowak wrote:
> We have transformation with many resources (we have plenty of them in
> our case). Using this transformation generates applied rule
> with one simulation movement, again applied rule, then more than 50
> simulation movements which has AR/SM pair. Supply chain is quite simple
> - two nodes.
>
> Invoking expand method on root of this tree lasts for about 80 seconds
> on not loaded system, with hardware RAID0 on PCI-X and is consuming
> 100% of core of Opteron 265.
>
> My questions:
>  - ZEO won't help in this case directly, as expand is one method in
> activites? (we are going to use ZEO anyway)

Without customization, no.

>  - does expand need to be so CPU intensive?

expand is always CPU-bounded (unless MySQL becomes a bottleneck).

>  - is there any way/idea to split expand into few smaller expands and
> use clustering for them?

It is difficult to suggest an appropriate way without looking at your system.

Basically, the simulation system in ERP5 is created with flexibility and power 
in mind. This is very good in most cases. But as in your case, it can be slow 
in some cases, thus a sort of optimization is required.

The best way is to first profile it and understand what the bottleneck is (as 
written in erp5.org). Intuitively, as you have many applied rules, the 
selections of rules might be the bottleneck, because this part is completely 
dynamic, so that we can specify very complex criteria to select an 
appropriate rule. But this is sometimes overkill, and it could be acceptable 
to "hardcode" rules in many cases. However, it is very dangerous to assume 
something is a bottleneck without verifying it, since it can be a premature 
optimization, and can rather decrease the performance / flexibility

> And another question: are there any updated
> guidelines/documentation/ideas/experience docs/tips/anything about using
> ZEO with ERP5?
>
> I didn't suppose to find HowToUseZeo on ERP5 wiki ;), but there is not
> too much info about this on wiki. Well - maybe it is so simple, that is
> not worth mentioning it?

As you guess, it is so simple. How to set up ZEO is described in the Zope 
Book, so I didn't feel that it would be worth writing in the wiki.

YO
-- 
Yoshinori Okuji, Nexedi CTO
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