Re: Thread discussion

> -----Original Message-----
> From: Bruce Momjian [mailto:pgman@candle.pha.pa.us]
> Sent: Friday, July 05, 2002 7:59 PM
> To: PostgreSQL-development
> Subject: [HACKERS] Thread discussion
>
>
> There was an interesting thread/process discussion in the gproff
> Slashdot discussion:
>
>
> http://slashdot.org/article.pl?sid=02/07/05/1457231&mode=neste
d&tid=106

This guy had interesting comments:
http://slashdot.org/~pthisis/

Especially this comment:
http://slashdot.org/comments.pl?sid=35441&cid=3829377

==================================================================
Which is pretty much pointless MS bashing and incorrect.

From the news:comp.programming.threads FAQ:
Q147: Thread create timings

Matthew Houseman  writes:

Thought I'd throw this into the pyre. :)  I ran the thread/process
create
stuff on a 166MHz Pentium (no pro, no mmx) under NT4 and Solaris x86
2.6:


NT spawn                240s    24.0  ms/spawn
Solaris spawn (fork)    123s    12.3  ms/spawn  (incl. exec)
Solaris spawn (vfork)    95s     9.5  ms/spawn  (incl. exec)

Solaris fork             47s     4.7  ms/fork
Solaris vfork                    0.37 ms/vfork  (37s/100000)

NT thread create         12s     1.2  ms/create
Solaris thread create            0.11 ms/create (11s/100000)


As you can see, I tried both fork() and vfork(). When doing an immediate
exec(), you'd normally use vfork(); when just forking, fork() is usually
what you want to use (or have to use).

Note that I had to turn the number of creates up to 100000 for vfork
and thread create to get better precision in the timings.


To remind you, here are greg's figures (on a Pentium MMX 200MHz):

>NT Spawner (spawnl):            120 Seconds (12.0 millisecond/spawn)
>Linux Spawner (fork+exec):       57 Seconds ( 6.0 millisecond/spawn)
>
>Linux Process Create (fork):     10 Seconds ( 1.0 millisecond/proc)
>
>NT Thread Create                  9 Seconds ( 0.9 millisecond/thread)
>Linux Thread Create               3 Seconds ( 0.3 millisecond/thread)


Just for fun, I tried the same thing on a 2 CPU 170MHz Ultrasparc.
I leave it to someone else to figure out how much of this is due to
the two CPUs... :)

Solaris spawn (fork)            84s     8.4  ms/spawn  (incl. exec)
Solaris spawn (vfork)           69s     6.9  ms/spawn  (incl. exec)

Solaris fork                    21s     2.1  ms/fork
Solaris vfork                           0.17 ms/vfork  (17s/100000)

Solaris thread create                   0.06 ms/create (6s/100000)


=================================TOP=============Q148: Timing Multithreaded Programs (Solaris)

From: sullivan@aisg20a.erim.org (Richard Sullivan)

>I'm trying to time my multithreaded programs on Solaris with multiple
>processors.  I want the real world running time as opposed to the total

>execution time of the programming because I want to measure speedup
versus
>sequential algorithms and home much faster the parallel program is for
the user.

Bradly,
 Here is what I wrote to solve this problem (for Solaris anyway).  To
use it just call iobench_start() after any setup that you don't want
to measure.  When you are done measuring call iobench_end().  When you
want to see the statistics call iobench_report().  The output to
stderr will look like this:

Process info: elapsed time  249.995 CPU time      164.446 user time     152.095 system time   12.3507 trap time
0.661235wait time     68.6506 pfs    major/minor    3379/     0 blocks input/output      0/     0 
65.8% CPU usage

The iobench code is included in the program sources on: index.html.
=================================TOP=============

My opinion is that PostgreSQL does not have to exclusively fork() or
exclusively thread.
As Spike Lee said:
"Always do the right thing."