[Ruby-DBI-devel] [mneumann@ntecs.de: Re: ruby-postgres blocks all threads]

[Florian G\. P. <fg...@ph...>]

----- Forwarded message from Michael Neumann <mne...@nt...> -----

Envelope-to: fgp@localhost
Delivery-date: Tue, 06 May 2003 14:22:43 +0200
From: Michael Neumann <mne...@nt...>
To: "Florian G. Pflug" <fg...@ph...>
Subject: Re: ruby-postgres blocks all threads

On Tue, May 06, 2003 at 01:05:05PM +0200, Florian G. Pflug wrote:
> Hi
> 
> I discovered today that ruby-postgres uses the blocking postgres api when
> calling PGconn::exec / PGconn::query. This implies, that all other ruby
> threads are blocked until a result is available.
> 
> There are, however, the function PGconn::async_exec and PGconn::async_query
> which properly use the nonblocking postgresql api, and use rb_thread_select
> to put the calling thread to sleep until the database backend responds.
> 
> These functions are not, as the name might imply, truly asynchronous, in the
> sense that they return immediatly after sending the query. They seem (at
> least when reading the code) to be a drop-in replacement for exec and query,
> but with a more cooperative behaviour.

And I thought they were truly asynchronous, so I did not used them.

But there might be performance issues. Could you write a simple
benchmark, comparing the time needed to insert several thousand rows
into Postgres with both variants?

> I would recommend to use those functions in the postgres dbd module.
> 
> I did not attach a patch, because simply replacing exec with async_exec is
> probably easier than applying a patch ;-))

That's indeed easier.

> greetings, Florian Pflug

Please post this mail for discussion to the ruby-dbi-devel mailing-list, too.

Thanks!


Regards,

  Michael


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