DCE Application Programming Guide

HP NonStop DCE Application Programming Guide—429551-003

3-1

Application Programming With

NonStop DCE Threads

NonStop DCE threads is a user space implementation of OSF DCE threads for use by

OSS processes. This section provides guidelines for developing NonStop DCE

applications and assumes that the reader is familiar with the information in the volumes

of the OSF DCE Application Development Guide.

NonStop DCE Threads

Threads are scheduled for execution by the threads library, not the NonStop operating

system. All threads created within a process share the same process address space.

With NonStop DCE, one thread can never be preempted by another thread. Each

thread executes until it relinquishes control. Control is relinquished when the thread

either waits on a mutex or condition variable, issues an RPC, or explicitly calls the

pthread_yield() function.

All resources of a process—for example, open files or memory—belong to one of the

two categories: global or shared, as outlined in Table 3-1. Private resources can be

accessed only by a specific thread. Global resources can be accessed by all threads.

Access to global resources should be synchronized using mutex or condition variables.

Table 3-1. Process Resource Types (page 1 of 2)

Resource Type Description

Thread stack Private for

TNS

applications;

global for

TNS/R and

TNS/E

applications

The memory where all thread-local

variables are stored

Thread program counter Private The address of the instruction that the

thread is about to execute

Thread context Private The data maintained by the thread library

on behalf of a thread

All external data Global Includes process and module global

resources

All static internal variables Global

Heap Global

File descriptors and file state Global Includes file and record locks