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POHow do I Spawn threads from two different objects and coordinate them in python v2.7?
 

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  1. POHow do I Spawn threads from two different objects and coordinate them in python v2.7?
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    <p>I am trying to combine the answers I got from two different python questions.</p> <p>Here is the the first question and answer. Basically I just wanted to spawn two threads, one to powerDown() and the other to powerUp(), where powerUp() pends on powerDown()</p> <p><a href="https://stackoverflow.com/questions/18989472/how-to-spawn-a-thread-inside-another-thread-in-the-same-object-in-python">How to spawn a thread inside another thread in the same object in python?</a></p> <pre><code>import threading class Server(threading.Thread): # some code def run(self): self.reboot() # This is the top level function called by other objects def reboot(self): # perhaps add a lock if not hasattr(self, "_down"): self._down = threading.Thread(target=self.__powerDown) self._down.start() up = threading.Thread(target=self.__powerUp) up.start() def __powerDown(self): # do something def __powerUp(self): if not hasattr(self, "_down"): return self._down.join() # do something del self._down </code></pre> <hr> <p>Here is the the second question and answer. Basically I wanted to start a thread, and then call a function of the object.</p> <p><a href="https://stackoverflow.com/questions/19033818/how-call-a-function-on-a-running-thread-python">How to call a function on a running Python thread</a></p> <pre><code>import queue import threading class SomeClass(threading.Thread): def __init__(self, q, loop_time = 1.0/60): self.q = q self.timeout = loop_time super(SomeClass, self).__init__() def onThread(self, function, *args, **kwargs): self.q.put((function, args, kwargs)) def run(self): while True: try: function, args, kwargs = self.q.get(timeout=self.timeout) function(*args, **kwargs) except queue.Empty: self.idle() def idle(self): # put the code you would have put in the `run` loop here def doSomething(self): pass def doSomethingElse(self): pass </code></pre> <p>Here is combined idea code. Basically I wanted to spawn a thread, then then queue up a functions to execute, which in this case is reboot(). reboot() in turns creates two threads, the powerDown() and powerUp() threads, where powerDown() pends on powerUp()</p> <pre><code>import threading import Queue class Server(threading.Thread): def __init__(self, q, loop_time = 1.0/60): self.q = q self.timeout = loop_time super(Server, self).__init__() def run(self): while True: try: function, args, kwargs = self.q.get(timeout=self.timeout) function(*args, **kwargs) except queue.Empty: self.idle() def idle(self): # put the code you would have put in the `run` loop here # This is the top level function called by other objects def reboot(self): self.__onthread(self.__reboot) def __reboot(self): if not hasattr(self, "_down"): self._down = threading.Thread(target=self.__powerDown) self._down.start() up = threading.Thread(target=self.__powerUp) up.start() def __onThread(self, function, *args, **kwargs): self.q.put((function, args, kwargs)) def __powerDown(self): # do something def __powerUp(self): if not hasattr(self, "_down"): return self._down.join() # do something del self._down </code></pre> <p>All work, except when I create two Server subclasses.</p> <pre><code>class ServerA(Server): pass class ServerB(Server): pass </code></pre> <p>Here is the code that instatiats both subclasses, and call the start() and reboot functions</p> <pre><code>serverA = ServerA(None) serverB = ServerB(None) serverA.start() serverB.start() serverA.reboot() serverB.reboot() </code></pre> <p>I expect serverA.reboot() and serverB.reboot() to happen concurrently, which is what I want, but they DO NOT! serverB.reboot() gets executed after serverA.reboot() is done. That is, if I put print statements, I get</p> <pre><code>serverA started serverB started serverA.reboot() called serverA.__powerDown called serverA.__powerUp called serverB.reboot() called serverB.__powerDown called serverB.__powerUp called </code></pre> <p>I know for a fact that it takes longer for ServerA to reboot, so I expect something like this</p> <pre><code>serverA started serverB started serverA.reboot() called serverB.reboot() called serverA.__powerDown called serverB.__powerDown called serverB.__powerUp called serverA.__powerUp called </code></pre> <p>I hope that makes sense. If it does, why aren't my reboot() functions happening simultaneously?</p>
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      1. POHow do I Spawn threads from two different objects and coordinate them in python v2.7?
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    1. COIf I just use the sample code from the first post, I can non-sequentially execute code; that is, I get my expected non-sequential powerDown/powerUp's from the two server objects.
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      1. POHow do I Spawn threads from two different objects and coordinate them in python v2.7?
      1. USChris F
 

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