Use "--set gdk_nr_threads=N", when I invoke mserver5? Can you give me a sample command? I used the source code checked out in January. Do I need to check out the new source and rebuild Monetdb5 Thanks a lot. Xiang Martin Kersten wrote:
xxiao wrote:
Hi, Martin
We are doing some research on how MonetDB will perform on multi-core machines. So, in the first place, we would like to understand how MonetDB utilize multiple threads to process a query. This is part of an on-going research project we should be aware of?
According to you, M5/SQL with dataflow optimizer forks multiple threads to process a single query plan. To activate dataflow optimizer, do I use flag "--enable-optimize" when I build M5? Do you know what files I may look at to get a overall view of the thread implementation? Thanks a lot.
--enable-optimize drives the parameters of the C-compiler only
The dataflow optimizer is part of CURRENT, it is enabled by default for about four months nowe. This is covered by the file sql_optimizer.mx. The optimizer is src/optimizer/opt_dataflow.mx en supported in the interpreter src/mal/mal_interpreter.mx
You can control the maximum number of threads using the argument --set gdk_nr_threads=N
Xiang
Martin Kersten wrote:
xxiao wrote:
Hi,
does anyone know whether there is any doc on how the server is implemented in Pthreads, such as how many threads are forked and what job each different thread is responsible for?
The source is the most complete documentation in this ;) The number of threads depend on the back end used and the advice coming from the frontends.
In the M5/SQL setting each client connection receives its own thread of control. Within a single query plan multiple threads of control may become active when the dataflow optimizer is activated.
There is one thread awaiting connection requests and a separate thread to flush memory.
Please explain what you plan to do in this area.
regards, Martin
Thanks a lot.
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