Re: libpthread vs libthr.

On Sunday 12 November 2006 07:03, Chris wrote:
On 10/11/06, Nikolay Pavlov <quetzal@xxxxxxxxxxxx> wrote:
Hi. In this post i am not trying to raise a discussion about teoretical
advantages of some special threading model, but still i would like to
figure out why libthr in it current state is not our default posix
thread library and could it be so in time of 7-STABLE?

As a user and administrator of FreeBSD i want to mention some benefits
of libthr:

1. It's simpler.
2. It's stable and has been used by many of us for a long time.
3. It proved to be very productive on real world applications.
4. It has active talented developers.
5. If it was a default library it would couse a incrase of users
feedback which would lead to futher improvement of it's code by the time
7 becomes a stable branch.

And some flaws of libpthread:

1. It's more difficult.
2. It's slow in compare of libthr.
3. The last, but the worst. IMHO the position under which libpthread is
the library by default is the source of a bad myth that threading model
in FreeBSD sucks and threading applications is slow. If 7.0 had libthr
as a default posix threads library we could brake that belief.

This point of view may seem one-sided that is why someone with good
knowledge of the current state of code could tell other pros and cons
of both libraries.

Another interesting question is which of the libraries will better work
with multikernel and multiprocessor systems which will be very popular
by the time 7.0 branch launches its stable releases.

--
======================================================================
- Best regards, Nikolay Pavlov. <<<-----------------------------------
======================================================================

HI I posted in another thread about how my own experiences seem to
differ from all these benchmarks, they are based on 3 heavily loaded
web/mysql servers.

One is freebsd 6.1 dual core cpu (not htt). 2nd is dual xeon freebsd
6.1 and 3rd is another dual xeon freebsd 6.1.

All 3 of these machines perform better as well as more stable under
higher loads using libpthread process scope.

System scope appears to make mysql hog the system and everything slows
down except of course mysql.

Libthr appears to make mysql very sporadic with some requests fast
others with a unexplained 5-10 sec delay including timeouts.

Process scope on libpthread gives me the best results not making mysql
starve the server of resources and it has a consistent response time
of under 2 seconds under hevay loads.
libthr on FreeBSD 6.1 respects process scope, if your mysql is compiled
with process scope, it will use it, this is only removed in -CURRENT,
I don't know why you said that it starved server resource if KSEGRP
really works as expected.


I cant explain other then it maybe that test mysql data isnt a proper
way to test these threading libraries only real work loads can.

Chris
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