Re: PThreads

From: Damian Dixon (damian.dixon_at_[hidden])
Date: 2000-08-25 03:08:38

Thomas O Matelich wrote:
>
>Milutin Jovanovic wrote:
>
>> Sorry for being off-topic, but the reason behind questions is our present
>> thread discussion.
>>
>> How standard are pthreads on UNIX? Is there a universal distribution, or
are
>> there separate platform distributions which are trying to be compatible
>> amongst each other? Where is the best place to get pthreads for Linux
and/or
>> Windows?
>
>On HP-UX 10.2, pthreads are whats used.  They are part of the DCE
(Distributed
>Computing Environment) 9000 system used -- whatever that means.  I believe
the
>pthreads are also used on HPUX 11, the difference, as I understand it,
between
>10.2 and 11 is on 10.2 they are referred to as user threads and on 11 they
are
>kernel threads.  I don't know much about it besides this.

Sorry for also being off-topic.

pthreads are available on Solaris as well. Though I have had
problems with the Solaris 2.7 version of pthreads.

From man standards on Solaris:
         | POSIX.1c-1996  |  threads extensions            |  Solaris 2.6|

I believe pthread's are also available on SGI's but can't confirm
at the moment as my SGI is not working at the moment.

There are problems with threads in general on HP-UX 10.20 in
that they are process threads (user threads) rather then kernel
threads (HP-UX 11.x).

A simplistic view of the differences between Process threads
and Kernel threads are:

o Process threads run in one Unix process. Blocking IO blocks
  all threads.

o Kernel threads are viewed as multiple processes and thus if
  a thread blocks on IO the other threads are not also blocked. 

Because HP-UX 10.20 only has process threads any programs written
using threads and X suffer from a performance hit because of
blocking in the X libraries (I put this down to a poor implementation
of thread support in the X libraries).

IMHO I would prefer to see pthreads used as the underlying mechanism
for the thread library.

However the quality of the pthread implementation differs from
UNIX platform to UNIX platform as well as the version of the
pthread library supported.

Regards,
Damian
----------------------------------------------------------------------------
-----------------------
Damian Dixon, BSc(Hons), BSc(Hons), FRGS
ODS Design Authority
Senior Software Development Engineer
TENET Defence Ltd.
North Heath Lane
Horsham
West Sussex
RH12 5UX

Tel: 	[phone]
Fax: 	[phone]
Email:	damian.dixon_at_[hidden]
http://www.tenetdefence.com

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