[Python编程(第4版)].(Programming.Python.4th.Edition).Mark.Lutz.文字版

Forking Processes Forked processes are a traditional way to structure parallel tasks, and they are a fun- damental part of the U ...

Programs generally test this result to begin different processing in the child only; this script, for instance, runs the child f ...

call simply pauses the calling process for a number of seconds (you can pass a floating- point value to pause for fractions of s ...

[6476] => 2 [6684] => 2 ...more output omitted... The output of all of these processes shows up on the same screen, becaus ...

os.exec call formats The arguments to os.execlp specify the program to be run by giving command-line arguments used to start the ...

Spawned child program Just as when typed at a shell, the string of arguments passed to os.execlp by the fork- exec script in Exa ...

More on Cygwin Python for Windows As mentioned, the os.fork call is present in the Cygwin version of Python on Windows. Even tho ...

Fourth Edition Update: As I was updating this chapter in February 2010, Cygwin’s official Python was still Python 2.5.2. To get ...

scope variables, passed objects and their attributes, and program-wide interpreter components such as imported modules are share ...

Luckily, the Python queue module, described in this section, makes this simple: realistic threaded programs are usually structur ...

to manage threads with high-level class-based objects. Both modules also provide tools for synchronizing access to shared object ...

print('Hello from thread', tid) def parent(): i = 0 while True: i += 1 _thread.start_new_thread(child, (i,)) if input() == 'q': ...

Each message here is printed from a new thread, which exits almost as soon as it is started. Other ways to code threads with _th ...

uses time.sleep so that the main thread doesn't die too early-- this kills all other threads on some platforms; stdout is shared ...

[3] => 0 [1] => 1 [3] => 1 [3] => 1 [0] => 1[2] => 1 [3] => 1 [0] => 1[2] => 1 [4] => 1 [1] => ...

will silently corrupt the state of the shared object completely): one thread may step on the work done so far by another whose o ...

ever execute a print call at the same point in time; the lock ensures mutually exclusive access to the stdout stream. Hence, the ...

Example 5-8. PP4E\System\Threads\thread-count-wait1.py """ uses mutexes to know when threads are done in parent/main thread, ins ...

exitmutexes = [False] * 10 def counter(myId, count): for i in range(count): stdoutmutex.acquire() print('[%s] => %s' % (myId, ...

Passing in the lock to threaded functions as an argument instead of referencing it in the global scope might be more coherent, t ...