Themes in Java and Python

Question

I have few questions about threads in Python and Java ...

• Is it possible to set priorities for Python threads, as in Java?
• How can I kill, stop, pause and interrupt a thread in Python?
• Groups of topics - what are they for? Does Python support them?
• Synchronization - in Java we just use the synchorinized keyword for a method, object ... What about Python?

Tnx!

Answer 1

Assuming we're talking about implementing a classic (CPython):

• no, no priorities in Python threads
• you cannot do any of these things in a thread in python
• no thread groups in Python
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Answer 2

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Answer 3

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http://docs.python.org/library/sys.html#sys.setcheckinterval

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http://docs.python.org/c-api/init.html#PyThreadState_SetAsyncExc

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Answer 4

, , ( , if-self.alive ):

import threading, Queue

class HaltableThread(object.Thread):
    def __init__(self):
        self.stringQueue = Queue.Queue()
        self.alive = True
    def run(self):
        while self.alive:
            try:
                data = self.stringQueue.read(0.01) #100ms block until data
            except Queue.Empty:
                pass
            else:
                print data
    def stop(self):
        self.alive = False

Answer 5

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SCJP:

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Answer 6

Unfortunately, the standard Python package has something called a GIL, or global interpreter. This means that only one of your threads will work at a time. At the same time, simple multi-threaded applications are possible and quite easy to write. The streaming module contains basic synchronization primitives such as mutexes, sempahores, etc.

There is also a wonderful instruction manual that automates most aspects of locking. For example:

import threading
myLock = threading.Lock()

Then to use the lock:

with myLock:
    #lock has now been acquired
    print "I have the lock and can now to fun stuff"
print "The lock has been released"