A way to build and install libpthread as 1:1 as well as M:N?

[Alex Keahan]

On Sunday 18 Jul 2004 7:30 pm, Daniel Eischen wrote:
> On Sun, 18 Jul 2004, Robert Watson wrote:
> > I'm doing some stability and performance testing as part of the network
> > stack locking work.  I'd like a way to easily plug and play the
> > configuration of libpthread at run-time (although restarting apps is
> > fine, rebooting is less preferable, as is actually rebuilding!).  It
> > looks like right now if I want to switch the operating mode of libpthread
> > to 1:1, I have to recompile it with different compile options and have a
> > separate library floating around that I plug.  Could we arrange for it to
> > be a runtime switch of some sort (perhaps read once when the app starts),
> > or build the library both ways by default and intall with different
> > names?
>
> The way to do this so it is switchable without relinking
> the application (and without using libmap.conf) is to use
> LD_LIBRARY_PATH.  You can install libpthread built as 1:1
> anywhere you like and just set LD_LIBRARY_PATH to wherever
> it is installed.
>
> If you want both 1:1 and M:N versions of libpthread installed
> by default, we have to decide where to install the 1:1 version.
> I would recommend 1:1 go in lib/lwp/libpthread.so.1 and M:N
> in lib/libpthread.so.1.  You could change "lwp" to "kse"
> or something else.

How about:

M:N libpthread:  /usr/lib/libpthread.so
1:1 libpthread:  /usr/lib/lwp/libpthread.so
1:1 libthr: /usr/lib/thr/libpthread.so?

or 

M:N libpthread:  /usr/lib/libpthread.so
1:1 libpthread:  /usr/lib/kse/libpthread.so
1:1 libthr: /usr/lib/lwp/libpthread.so?

I think all the POSIX thread libraries should be called "libpthread.so"
instead of libpthread, libthread, libc_r.   Then you can compile things once
and select the library you want at runtime by setting the dynamic linker
search path (or at link time using the -R linker switch.)

In essense, this would be similar to Solaris.

Solaris 8 has two POSIX threads libraries (libpthread.so):

M:N, located in
	/usr/lib (32-bit) and
	/usr/lib/sparcv9 (64-bit), and
1:1, located in
	/usr/lib/lwp (32-bit) and
	/usr/lib/lwp/sparcv9 (64-bit)

Solaris 9 has only one libpthread (1:1) in:
	/usr/lib (32-bit) and
	/usr/lib/sparcv9 (64-bit)

(Their 1:1 libpthread is probably more like our "libthr" than
"libkse/libpthread in 1:1 mode".)

As a side note, Solaris also has a "libthread" which is *not* a POSIX
thread library - it implements "Solaris threads" - it's *not* like our
libthr which implements *POSIX threads*.

Alex Keahan