[Monetdb-developers] About monetdb's thread

Stefan Manegold Stefan.Manegold at cwi.nl
Thu Jul 29 13:33:39 CEST 2010

Hi Kun Ren,

we do not know of a simple way (e.g., system call) to find out the number of
CPU cores on a Windows system, hence, we set the default number of threads
in the MonetDB kernel to 1.

You can overrule this by starting mserver5 with an extra command line option
"--set gdk_nr_threads=<N>" or adding a line "gdk_nr_threads=<N>" to you
monetdb5.conf file.
In either case, <N> shoudl be the number of threads you'd like to have
(should not be larger than the number of CPU cores).

However, we do not know how well the multi-threading works on Windows. We
rely on pthreads, and their implementation on Windows might not be as
efficient and/or stable as on Unix-like systems ...

Hope this helps you further ...


On Fri, Jul 23, 2010 at 09:33:21AM +0800, kun ren wrote:
> Dear all,
>    hello,all, I download the windows installer of monetdb,and install,and
> then start MonetDB server, my computer has 4 cpus.and with 32bit windows xp
> ,but the MonetDB server only start one thread.when I run MonetDB in Linux
> with 2 cpus, it start 2 threads. so why? why I am in Windows xp with 4 cpus,
> it only create 1 thread ?

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| Dr. Stefan Manegold | mailto:Stefan.Manegold at cwi.nl |
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