Marc,
not only the global variables are a problem. PostgreSQL doesn't clean
up
all the memory before a process terminates and you must deal with
signals between threads.
I've modified PostgreSQL that it is completely thread based and nearly
clean
with allocating/deallocating memory and I'm using signals between
threads.
I've written the code that it's easy to combine the changes with new
releases of
PostgreSQL but it has some problems that require a decrease of the
number of
global variables. This is very hard if you don't want to drift away
from the
main sourcecode of PostgreSQL.
Actually I have a table that holds all the globals that needs to be
addressed
and I can tell you that there are a lot of global variables.
However. I've tried to give the changes with the memory freeing back to
the
main source tree but my feeling was that they don't like it because it
doesn't
matter on UNIX if you're only process based. The same with several
tools like
PSQL. After this I wanted to look closer at the global variables.
If this may change in the future you would be very happy if you don't
have to
search for unreleased memory because it is solved.
I'm still VERY interested in giving those changes back to the
community,
but i think that my changes are still not wanted.
Another problem I have is that the build tools i'm using are not GNU
and
the project file is different in this case. The developers from
PostgreSQL
don't want this too.
Currently i'm working on a project file that uses GNU make but i'm not
very
happy with this because it is dramatically slower compared to the
Metrowerks Tools. With Codewarrior I can build PostgreSQL in around
2 Minutes with all libraires and so on and GNU make needs much much
longer.
But I still hope that I'll find a way how I can handle all this.
PostgreSQL itslef is running very good with "only threads" and the
database
itself is a VERY GOOD product.
In the future I'll make some tests to find out information about the
performance
and how threads affect the performance on Linux.
I'm also working on several additions to PostgreSQL for remote realtime
Monitoring
and configuration, LDAP authentication and more.
Ulrich
>>> "Marc G. Fournier" <scrappy@hub.org> 18.10.2002 05:21:59 >>>
On Wed, 16 Oct 2002, Anuradha Ratnaweera wrote:
> On Wed, Oct 16, 2002 at 01:25:23AM -0400, Bruce Momjian wrote:
> > Anuradha Ratnaweera wrote:
> >
> > > ... what I want to know is whether multithreading is likely to
get
> > > into in postgresql, say somewhere in 8.x, or even in 9.x?
> >
> > It may be optional some day, most likely for Win32 at first, but we
see
> > little value to it on most other platforms; of course, we may be
wrong.
>
> In that case, I wonder if it is worth folking a new project to add
> threading support to the backend? Of course, keeping in sync with
the
> original would be lot of work.
Actually, if you go through the archives, there has been talk about
what
would have to be done to the main source tree towards getting
threading
included ... as well as a lengthy discussion about the steps involved.
the first and foremost issue that needs to be addressed is cleaning up
the
global variables that are used throughout ...
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