Re: GP parfor is really cool

[Bill Allombert <Bill.Allombert@math.u-bordeaux.fr>]

On Mon, Dec 29, 2025 at 06:39:40PM +0100, hermann@stamm-wilbrandt.de wrote:
> I used parfor earlier sometimes, with my 16C/32T AMD 7950X CPU.
> 
> 
> Yesterday I needed to check >2600 >10,000 decimal digit numbers with
> ispseudoprime() and report prime candidates only.
> 
> I did start with another unrelated process running with 100% CPU
> utilization. That was a problem, since gp took 3200 CPU%, and the machine
> became unresponsive. It was pingable, but new ssh into was not possible.
> After two minutes ^C was displayed in existing ssh session, and after more
> minutes I was able to execute "killall gp" and all was fine again.
> 
> Next I did run with numactl restricting gp to 16 threads, and all was fine:

Note that you can use
default(nbthreads, xxx) to set the number of threads.

The default is the number of threads reported by the OS.

Cheers,
Bill