Date: Wed, 05 Sep 2001 15:15:03 -0700 (PDT) From: John Baldwin <jhb@FreeBSD.org> To: John Baldwin <jhb@FreeBSD.org> Cc: Ullasan_Kottummal@kindlebanksys.com, freebsd-hackers@FreeBSD.org, Terry Lambert <tlambert2@mindspring.com> Subject: Re: Posix Threading Message-ID: <XFMail.010905151503.jhb@FreeBSD.org> In-Reply-To: <XFMail.010905144724.jhb@FreeBSD.org>
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[ I really hate it when my window manager gets stuck in a loop spinning while
I'm composing a mail message and I forget to fix up the mail message.
*sigh* ]
> On 05-Sep-01 Terry Lambert wrote:
>> Ullasan_Kottummal@kindlebanksys.com wrote:
>>>
>>> Hi All,
>>> I am trying to create threads under HP-UX 11 using POSIX threads library
>>> and
>>> using the method pthread_create(...).
>>>
>>> But I don't know how can I create a thread in a suspended state.
>>
>> First the obligatory "off topic" humor:
>>
>> This is not the place to ask about HP-UX programming; you
>> probably want the Hewlet-Compaqard user's mailing list... 8-p.
>>
>> --
>>
>> If the intent is to have "a pool of idle threads", ready to
>> go when you get request traffic, and get around the latency,
>> well, you'd do a lot better in the latency department if you
>> went to a finite state automaton, instead of messing with
>> threads. But if you insist, the best you are going to be
>> able to get is use of a mutex, since a condition variable will
>> result in a "thundering herd" problem. You will still have to
>> eat the latency for the mutex trigger to the thread you give
>> the work to, however (this is how I designed the work-to-do
>> dispatcher in the Pathworks for VMS (NetWare) product for DEC
>> and Novell).
Most of what you say is ok, but this is wrong. condition variables do not
mandate using a wakeup all strategy. There is such a thing as 'signal' instead
of 'broadcast', which only wakes up one thread.
PTHREAD_COND_SIGNAL(3) FreeBSD Library Functions Manual PTHREAD_COND_SIGNAL(3)
SYNOPSIS
#include <pthread.h>
int
pthread_cond_signal(pthread_cond_t *cond);
DESCRIPTION
The pthread_cond_signal() function unblocks one thread waiting for the
condition variable cond.
--
John Baldwin <jhb@FreeBSD.org> -- http://www.FreeBSD.org/~jhb/
PGP Key: http://www.baldwin.cx/~john/pgpkey.asc
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