[Monetdb-developers] About monetdb's thread
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 ?
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 ... Stefan 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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On Thu, 29 Jul 2010, Stefan Manegold wrote:
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.
http://stackoverflow.com/questions/150355/programmatically-find-the-number-o... Is the three liner in there something MonetDB could use? Stefan
Thanks, professer Stefan.I will do my exprierment on linux.
2010/7/29 Stefan Manegold
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 ...
Stefan
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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_______________________________________________ Monetdb-developers mailing list Monetdb-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/monetdb-developers
-- | Dr. Stefan Manegold | mailto:Stefan.Manegold@cwi.nl | | CWI, P.O.Box 94079 | http://www.cwi.nl/~manegold/ | | 1090 GB Amsterdam | Tel.: +31 (20) 592-4212 | | The Netherlands | Fax : +31 (20) 592-4199 |
participants (3)
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kun ren -
Stefan de Konink -
Stefan Manegold