Programming Python, 3rd Edition

5.1. "Telling the Monkeys What to Do" Most computers spend a lot of time doing nothing. If you start a system monitor tool and watch the CPU utilization, you'll see what I meanit's rare to see one hit 100 percent, even when you are running multipl...

5.2. Forking Processes Forked processes are the traditional way to structure parallel tasks, and they are a fundamental part of the Unix tool set. It's a straightforward way to start an independent program, whether it is different from ...

5.3. Threads are another way to start activities running at the same time. In short, they run a function call in parallel with the rest of the program. are sometimes called "lightweight processes," because...

5.4. Program Exits As we've seen, unlike C, there is no "main" function in Python. When we run a program, we simply execute all of the code in the top-level file, from top to bottom (i.e., in the filename we listed in the command line, clicked in ...

5.5. Interprocess Communication As we saw earlier, when scripts spawn threadstasks that run in parallel within the programthey can naturally communicate by changing and inspecting shared global memory. As we also saw, some care must be tak...

5.6. Pipes Pipes, another cross-program communication device, are made available in Python with the built-in os.pipe call. are unidirectional channels that work something like a shared memory buffer, but with an interface resembling a simple...

5.7. Signals For lack of a better analogy, signals are a way to poke a stick at a process. Programs generate signals to trigger a handler for that signal in another process. The operating system pokes toosome signals are generated on...

5.8. Other Ways to Start Programs Suppose, just for a moment, that you've been asked to write a big Python book and you want to provide a way for readers to easily start the book's examples on just about any platform that Python runs on. Book...

5.9. A Portable Program-Launch Framework With all of these different ways to start programs on different platforms, it can be difficult to remember what tools to use in a given situation. Moreover, some of these tools are called in ways that are c...

5.10. Other System Tools In this and the prior two chapters, we've met most of the commonly used system tools in the Python library. Along the way, we've also learned how to use them to do useful things such as start programs, process directories,...