AIX Version 4.3 Differences Guide

4.4 Pthreads Suspend and Resume (4.3.2)
The pthreads library has been enhanced to provide the ability to suspend and
resume individual threads. This function is added to AIX 4.3.2 to assist in the
porting of applications from other platforms.
The pthreads implementation on AIX 4.3.2 complies with the UNIX98 standard.
The four new API functions are not part of this standard, and this is indicated by
appending _np to their names to indicate that they are NON-POSIX compliant.
The four new user functions are:
• int pthread_suspend_np(pthread_t thread);
• int pthread_continue_np(pthread_t thread);
• int pthread_attr_setsuspendstate_np(pthread_attr_t *attr, int
suspendstate);
• int pthread_attr_getsuspendstate_np(pthread_attr_t *attr, int
*suspendstate);
The pthread_suspend_np and pthread_continue_np functions are used to
immediately suspend and resume execution of the thread indicated by the
function argument.
The pthread_attr_getsuspendstate_np and pthread_attr_setsuspendstate_np
functions are used to get and set the value of the new suspendstate member of
the pthread_attr_t structure. The suspendstate argument can be set to either
PTHREAD_CREATE_SUSPENDED_NP or
PTHREAD_CREATE_UNSUSPENDED_NP. The default value of the
suspendstate attribute of a pthread_attr_t structure is
PTHREAD_CREATE_UNSUSPENDED_NP.
The new functions work in both the 1:1 and M:N threading environments.
4.5 Preserve Modified Ptrace Data (4.3.2)
AIX 4.3.2 has improved the performance of the ptrace() subroutine, which is
used by debuggers to control the execution of applications under their control.
Debuggers use a private copy of the text pages for the application being traced
and any shared libraries it uses. This allows the debugger to modify the text
pages to insert breakpoints without affecting any other processes on the system
that may be running the same executable or shared library text.
Prior to AIX 4.3.2, when the application being debugged calls the load(), or
loadbind() routines to load a private module into its address space, the system
loader reloads fresh copies of all the text pages for the application and any
required shared libraries. In so doing, any modifications made to the text pages
are lost, so the debugger has to reinsert breakpoints after the application calls
load() or loadbind().
The function of the ptrace routine has been modified along with the system loader
to maintain ptrace altered copies of text pages across calls to load or loadbind.
This will improve the performance of the debugger when controlling large
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