From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
---|---|
To: | Peter Eisentraut <peter_e(at)gmx(dot)net> |
Cc: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>, PostgreSQL-patches <pgsql-patches(at)postgresql(dot)org> |
Subject: | Re: Thread configure flag |
Date: | 2003-06-16 20:10:41 |
Message-ID: | 6399.1055794241@sss.pgh.pa.us |
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Lists: | pgsql-patches |
Peter Eisentraut <peter_e(at)gmx(dot)net> writes:
> Bruce Momjian writes:
>> If it is the default, libpq is going to use the libc_r library, at least
>> on some platforms, and that may not be desired.
> But what is the objective reason for this lack of desire?
I have heard that the reentrant libc is significantly worse-performing
than the non-reentrant one on some platforms. This is not real hard
to believe, since functions as common as malloc() will need locking
overhead if they think they might be in a multithreaded environment.
However, that's only an argument that we must provide a
--without-threads option, it doesn't speak strongly to the question of
what the default choice should be (where there is a choice).
> _POSIX_PTHREAD_SEMANTICS isn't used anywhere in the entire system, the
> effect of _THREAD_SAFE is to define _REENTRANT, and the effect of
> _REENTRANT is to declare getlogin_r(), which PostgreSQL sources don't use.
On which version of Linux are the above statements true? Are you sure
they are true on other versions?
regards, tom lane
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