Re: How can I reduce locking at storage level

How can I avoid database commit locks done by zope server for each http 
request. Even if most of the calls perform readonly transactions on 
database.


On Thursday, 3 March 2016 16:56:49 UTC+5:30, Jason Madden wrote:
>
> Oh, I probably should have mentioned: one can examine the Connections 
> joined to a transaction to determine if they have added or mutated any 
> objects, and decide to commit or abort based on that. But we found 
> that to not only be an invasion of the internal workings of the 
> transaction/Connection, but quite fragile (it's easy to modify objects 
> without realizing it). So we found looking at the higher semantic 
> level to be better, for us. 
>
> On Mar 3, 2016, at 02:44, Jason Madden <[email protected] 
> <javascript:>> wrote: 
>
> >> On Mar 3, 2016, at 01:19, Sanjay Rao <[email protected] <javascript:>> 
> wrote: 
> >> How can I make sure that locking is not done for such read-only 
> transactions ? 
> > 
> > I think the basic idea is to abort instead of commit such a transaction. 
> > 
> > How and when to do that, is I suppose it's probably application 
> > specific. For our own case of a WSGI (http) app, we wrote a custom 
> > transaction middleware (to replace the usual transaction middleware) 
> > that *always* aborts the transaction on requests that semantically 
> > aren't supposed to have side-effects, such as the common GET request. 
> > 
> > Not only did this eliminate a *lot* of locking for commits that 
> > /shouldn't/ change anything (at least under RelStorage), it helps 
> > enforce programmer discipline. There's been some private talk about 
> > this before, with the implication that it was at least a decent idea. 
> > 
> > It's really not complicated to write, although it does have to 
> > incorporate the retry logic usually found in other WSGI transaction 
> > managers, or at least our implementation did, IIRC--it's been awhile 
> > since I've checked. I can try to see about posting it somewhere if 
> > there's interest, though I suspect there's (again) some app-specific 
> > logic there so it may not be that helpful. 
> > 
> > Jason 
>

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