OpenServer 5.0.X has DCE threads which can be purchased in the US at 800-SCO-UNIX or any authorized SCO UNIX reseller/dealer. This is very expensive.

There are two possible GPL treads options available. Both were orginally submitted by ARTURO MONTES <mitosys@colomsat.net.co> Thanks!! There is a pthreads package on Skunkware 97. Custom installable media images for the OpenServer pthreads Skunkware package are at :

http://www.sco.com/skunkware/osr5/libraries/pthreads/VOLS.tar

This is proven's 1.60 Beta 5 Posix threads implementation ported to SCO OpenSever 5.0.X!

The second is FSU threads.

http://moss.csc.ncsu.edu/~mueller/pthreads/

A modified to work with OpenServer is available at

ftp://www.zenez.com/pub/zenez/prgms/threads.tar.gz

You need to use GDS in Skunkware 95 (95q4c). This is necessary because GNU gcc 2.7.2 in Skunkware 97 hasn't GNU as.
Currently there is an alpha version of mysql working with FSU threads. Tests are currently ongoing.

FSU Threads and Open Server 3.0 or Open Desktop 3.0
FSU pthreads can be compiled with SCO 4.2!! Use a good port of GCC 2.5.X
gerberb@zenez.com, robertlipe@usa.net

This is still a user-space threads library (because OSR5 has no kernel threads); it is a version of the UnixWare 7 libthread, modified to operate under the assumption that the number of available LWPs is always one (which is the case with no kernel threads).

Thus, you will see no performance benefit from using this threads library on MP systems. However, it does have better asynch I/O and libc synchronization than other OSR5 third-party user-space libraries (FSU, Pth) and so is recommended for use in UDK-based applications. The Java 1.4.2 implementation on OSR5 mp3/up3/supp3 also uses this new UDK libthread.
jls@sco.com