Date: Wed, 3 Nov 1999 07:46:52 -0600 From: "Richard Seaman, Jr." <dick@tar.com> To: Julian Elischer <julian@whistle.com> Cc: freebsd-arch@freebsd.org Subject: Re: Threads models and FreeBSD. (Next Step) Message-ID: <19991103074651.E5715@tar.com> In-Reply-To: <Pine.BSF.4.10.9911020044200.2283-100000@current1.whistle.com> References: <Pine.BSF.4.10.9911020044200.2283-100000@current1.whistle.com>
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On Tue, Nov 02, 1999 at 12:59:28AM -0800, Julian Elischer wrote:
[....]
> ---- possible userland implementation goals-----
>
> 1/ A libpthread that can be linked with libc.
>
> 2/ Libc needs to change so that library functions and system calls
> used internal to the library do not use the externally visible
> cancellable equivalents.
Can I suggest in addition to 2:
a) libc that is thread safe when used with libpthread (currently libc
is only partly thread safe, and even libc_r is not completely thread
safe).
b) hooks in libc to facilitate thread safe behaviour, specifically libc
structures that include locks, or pointers to locks as part of the
strcuture. This will probably require a version bump for libc, but
the alternative is really ugly (see John Birrell's implementation
of locking for the FILE structure as an example of what will have to
be repeated for other libc structures without locks as part of the
structures).
As a 3) can I suggest:
User land "system" libraries that are thread aware and thread safe (libgcc
is an example of one that is needed -- perhaps there are others) when used
with threaded applications
As a 4) can I suggest:
Debugger support for threads.
As a 5) can I suggest:
Well defined and industry standard methods for compiling and linking
threaded applications (currently FreeBSD's libc_r requirements for
compile/link are different from the most commonly used methods in other
pthreads implementations. Just browse through the ports to see what
FreeBSD specific changes have to be made to port threaded applications.
If we used more convetional compile/link requirements, porting would
be much easier).
--
Richard Seaman, Jr. email: dick@tar.com
5182 N. Maple Lane phone: 262-367-5450
Chenequa WI 53058 fax: 262-367-5852
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