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QNX Software Development Platform
QNX SDP is a cross-compiling and debugging environment, including an IDE and command-line tools, for building binary images and programs for target boards running QNX Neutrino 7.1.
Programming
Getting Started with QNX Neutrino
Getting Started with QNX Neutrino: A Guide for Realtime Programmers is intended to introduce you to the QNX Neutrino RTOS and help you develop applications and resource managers for it.
Processes and Threads
Process and thread fundamentals
Before we start talking about threads, processes, time slices, and all the other wonderful scheduling concepts, let's establish an analogy.

QNX Momentics IDE User's Guide
This User's Guide describes version 7.1 of the Integrated Development Environment (IDE) that's part of the QNX Momentics tool suite.
QNX Software Development Platform
QNX SDP is a cross-compiling and debugging environment, including an IDE and command-line tools, for building binary images and programs for target boards running QNX Neutrino 7.1.
- Quickstart Guide
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- Audio & Graphics API
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- Programming
  - Getting Started with QNX Neutrino
    Getting Started with QNX Neutrino: A Guide for Realtime Programmers is intended to introduce you to the QNX Neutrino RTOS and help you develop applications and resource managers for it.
    - Processes and Threads
      - Process and thread fundamentals
        Before we start talking about threads, processes, time slices, and all the other wonderful scheduling concepts, let's establish an analogy.
        A process as a house
        Let's base our analogy for processes and threads using a regular, everyday object: a house.
        The occupants as threads
        The people living in the house are the active objects—they're the ones using the various rooms, watching TV, cooking, taking showers, and so on. We'll soon see that's how threads behave.
        Back to processes and threads
        Just as a house occupies an area of real estate, a process occupies memory. And just as a house's occupants are free to go into any room they want, a process's threads all have common access to that memory. If a thread allocates something (mom goes out and buys a game), all the other threads immediately have access to it (because it's present in the common address space—it's in the house). Likewise, if the process allocates memory, this new memory is available to all the threads as well.
        Mutual exclusion
        If you want to take a shower, and there's someone already using the bathroom, you'll have to wait. How does a thread handle this?
        Priorities
        What if the bathroom is currently locked and a number of people are waiting to use it? Obviously, all the people are sitting around outside, waiting for whoever is in the bathroom to get out. The real question is, What happens when the door unlocks? Who gets to go next?
        Semaphores
        Let's move from the bathroom into the kitchen, since that's a socially acceptable location to have more than one person at the same time. In the kitchen, you may not want to have everyone in there at once. In fact, you probably want to limit the number of people you can have in the kitchen (too many cooks, and all that).
        A semaphore as a mutex
        We just asked the question Could you do it with a mutex? in relation to implementing a lock with a count, and the answer was no. How about the other way around? Could we use a semaphore as a mutex?
      - The kernel's role
        The house analogy is excellent for getting across the concept of synchronization, but it falls down in one major area. In our house, we had many threads running simultaneously. However in a single-processor system, only one thing can run at once.
      - Threads and processes
        Let's return to our discussion of threads and processes, this time from the perspective of a real live system. Then, we'll take a look at the function calls used to deal with threads and processes.
      - More on synchronization
      - Scheduling and the real world
        So far we've talked about scheduling policies and thread states, but we haven't said much yet about why and when things are rescheduled.
    - Message Passing
      In this chapter, we'll look at the most distinctive feature of QNX Neutrino, message passing. Message passing lies at the heart of the operating system's microkernel architecture, giving the OS its modularity.
    - Clocks, Timers, and Getting a Kick Every So Often
      It's time to take a look at everything related to time in the QNX Neutrino RTOS. We'll see how and why you'd use timers and the theory behind them. Then we'll take a look at getting and setting the realtime clock.
    - Interrupts
      In this chapter, we'll take a look at interrupts, how we deal with them under QNX Neutrino, their impact on scheduling and realtime, and some interrupt-management strategies.
    - Resource Managers
      In this chapter, we'll take a look at what you need to understand in order to write a resource manager. Resource managers are another distintive feature of QNX Neutrino that allow you to access services through standard POSIX calls.
    - Sample Programs
      This appendix contains the complete versions of some of the sample programs discussed in this book.
    - Glossary
  - Programmer's Guide
    The QNX Neutrino Programmer's Guide covers a variety of topics that might interest developers who are building applications that will run under the QNX Neutrino RTOS.
  - The QNX Neutrino Cookbook: Recipes for Programmers
  - Writing a Resource Manager
- Sensor Framework
- System Security Guide
  The QNX System Security Guide is intended for both system integrators who are responsible for the security of a QNX Neutrino RTOS system and developers who want to create a QNX Neutrino resource manager free from vulnerabilities.
- Utilities & Libraries
QNX Hypervisor
The QNX Hypervisor allows you to run multiple OSs on a target system so you can separate critical and non-critical functions, support a wide variety of applications, and reduce hardware costs.
QNX Software in the Cloud
QNX Software in the Cloud enables developers to use the QNX software in Amazon Web Services (AWS) and Microsoft Azure (Azure).
QNX Advanced Virtualization Frameworks User's Guide
This User's Guide is aimed at all systems integrators and developers who want to design and build embedded systems using the QNX Advanced Virtualization Frameworks.
Typographical Conventions, Support, and Licensing
This section describes the typographical conventions used throughout the documentation and explains how to obtain technical support.

Process and thread fundamentals

Before we start talking about threads, processes, time slices, and all the other wonderful scheduling concepts, let's establish an analogy.

What I want to do first is illustrate how threads and processes work. The best way I can think of (short of digging into the design of a realtime system) is to imagine our threads and processes in some kind of situation.

Page updated: March 12, 2026