H06.21 Release Version Update Compendium

2 Operating System
New POSIX User Thread Library for Multi-Threaded Application
Programming
This RVU introduces a new POSIX User Thread (PUT) Model library that enables customers to
write applications with non-blocking I/O both when making library calls such as fwrite() and
fread() and when making system calls such as write() and read(). The PUT library
provides support for thread-aware and thread-safe public DLLs, stack overflow detection, and
signal stack protection for multi-threaded application programming.
The PUT Model library is a user-space implementation of IEEE Std 1003.1, 2004, POSIX System
Application Program Interface Thread functions for use by native C and C++ applications in the
OSS environment on NonStop servers.
The previous Standard POSIX Thread (SPT) library continues to be supported, but you cannot
use both the PUT Model library and the SPT library in the same application.
For more information about the PUT Model library, see the Open System Services Programmer's
Guide.
Migration Considerations
Applications that use the SPT library are supported and do not require recompilation for them
to run on this RVU or later RVUs. However, if those applications are recompiled on systems
running this or later RVUs, they must include the _SPT_MODEL_ macro. For more information
about compiling applications that use the SPT library, see the Open System Services Programmer's
Guide.
To use the new PUT Model library in a new application or to convert existing applications that
use the SPT library to use the PUT Model library, see the Open System Services Programmer's Guide.
Fallback Considerations
For applications that use the SPT library, no specific steps are required to fall back to a previous
RVU. For applications that have been modified to include the _SPT_MODEL_ macro, no changes
are required because they can be compiled on systems running earlier RVUs.
Standard POSIX Threads Library: _SPT_MODEL_ macro Now Required for
Compilation
Beginning with this RVU, you must use the _SPT_MODEL_ macro when you compile applications
that use the Standard POSIX Threads library (applications that use the spthread.h header file).
You can use this macro for applications that use the Standard POSIX Threads library on earlier
RVUs also.
Migration Considerations
Applications that use the older Standard POSIX Thread library are supported and do not require
recompilation. Any applications that are compiled on systems running this RVU or later RVUs
must include the _SPT_MODEL_ macro.
Fallback Considerations
No specific steps are required to fall back to a previous RVU. Applications that use the
_SPT_MODEL_ macro can be compiled on systems running earlier RVUs.
New POSIX User Thread Library for Multi-Threaded Application Programming 13