[Xapian-discuss] Multithreaded read access

[Lucian Nicolescu]

Thanks a lot, things are clear now, this will definitely solve my problem.
I am planning a update to 1.0.2 but I need to thouroughly test it before and
reindex all documents.

Lucian Nicolescu  

> -----Original Message-----
> From: Richard Boulton [mailto:richard at lemurconsulting.com] 
> Sent: Wednesday, August 01, 2007 4:17 PM
> To: Lucian Nicolescu
> Cc: xapian-discuss at lists.xapian.org
> Subject: Re: [Xapian-discuss] Multithreaded read access
> 
> Lucian Nicolescu wrote:
> > Inside the xmlrpc server I only open the xapian database 
> for reading once.
> > This causes requests to "stay in line" in order to get 
> results and sometimes
> > a one operation can take up to 1 second to complete (a 
> time-taking operation
> > includes text analisys and some more operations besides the 
> actual Xapian
> > interaction) thus delaying all the queued requests.
> > 
> > I read lots of documents about xapian in mutithreaded 
> environment and
> > concluded that even for read access one cannot open the 
> same database more
> > than once and perform operations at the same time.
> 
> This is a misconception - for read access, you can open the same 
> database as many times as you like concurrently (well, as 
> many as your 
> operating system will allow - eventually, you'll run out of file 
> handles).  However, each of the Database objects you get by 
> opening the 
> database must not be accessed concurrently.  A typical model 
> might be to 
> create N threads, and use N Database objects, one for each thread.
> 
> > I am using Xapian 0.9.6, Python bindings and Twisted Python 
> XMLRPC package.
> 
> Just to note - Xapian 0.9.6 is rather old - the latest 
> release is 1.0.2. 
>   1.0.2 has the benefit that the Python bindings are set up 
> to release 
> the GIL whenever a potentially long-running xapian operation is in 
> progress,  which will give better performance in a concurrent 
> environment.
> 
> -- 
> Richard
>