On Nov 15, 2005, at 5:54 PM, Dennis Allison wrote:
Has anyone prepared a set of best practice guidelines on the
techniques to
use to minimize conflicts?
It is becoming clear that we need to do to refactor some of our
code to
get us out of our current conflict pickle.
A quick google produced lots of commentary but nothing I could hand
to our
programmers as guidelines.
Nothing in general except the (probably too general) "attempt not to
allow one process/thread to write to the same object at the same time
as another process/thread".
One tip, since you've told us you use sessions heavily: using ZEO to
back your session database provides more opportunity for conflicts
than if you used a "normal" Zope storage. This is because:
- the opportunity for conflict naturally grows as transaction time
increases and using a ZEO storage rather than a local storage adds
latency to the total transaction time that would not otherwise exist.
- you have "n" processes attempting to write to essentially the same
objects at the same time when you use a shared ZEO sessioning
database. If these were instead local databases, each process would
only compete "with itself" (between all of its threads).
I tend to try to use local sessioning databases backed by tempstorage
plus a frontend load balancer that allows for cookie-based session
affinity (Pound).
- C
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