Re: ithreads and sockets

At 08:36 -0500 8/31/03, Paul Archer wrote:
>10:48am, Elizabeth Mattijsen wrote:
>  > I'm afraid these prerequisites will disqualify using Perl ithreads
>>  for your application in a production setting.  This is caused by the
>>  fact that each Perl ithread gets a _copy_ of all data-structures in
>  > each thread.
>I'm curious about this memory usage per variable, though. If you don't share
>a variable, then that data shouldn't be copied from one thread to another,
>right? I mean, if one thread has a huge array, for example, then that
>shouldn't affect any other threads (or their memory usage) as long as the
>array isn't shared?

Nope.  Wrong.  The current Perl ithreads implementation copies 
everything data to each thread.  Yes, I know it sucks, but that's the 
way it is right now.  You can find some examples in a recent Perl 
Monks meditation: http://www.perlmonks.org/index.pl?node_id=288022 .


>Also, what about the shared variables in 5005threads? Was that the same
>copy-per-thread, or did 5005threads do things differently?

5.005 threads didn't copy anything, but made everything shared.  Even 
things you wanted private.  And it was never production ready.


>  > If you still want to use Perl ithreads, and are not worried about
>>  performance per se, you might want to have a look at the forks.pm
>>  module I wrote.  It basically has the same interface as Perl
>>  ithreads, but uses fork() to start threads (hence its name).  It also
>  > uses a TCP connection for each thread that has shared variables, so
>  > that may turn into a lot of sockets in your case.
>I'm curious about why you used TCP connections instead of Unix sockets. Was
>that to make it Windows compatible, or for some other reason? I understand
>Unix sockets are typically a good bit more efficient that TCP sockets on a
>local machine.

Primarily because I didn't figure it out how to use Unix sockets 
reliably from Perl.  I'm accepting patches  ;-)


Liz