---------- Forwarded message ---------- Date: Mon, 24 Apr 2006 07:32:04 -0400 From: Tino Dai <[EMAIL PROTECTED]> To: Danny Yoo <[EMAIL PROTECTED]> Subject: Re: [Tutor] Locking a specific variable
Hey there Danny, I'm not quite sure I get it, but ok. *grin* I'll assume that fileQueue is > an instance of the Queue class: > > http://www.python.org/doc/lib/module-Queue.html > > If so: why not allow fileQueue to grow unbounded? > > >> Presently, the only way that I can see to do this using Python is to >> combine the two functions into one and lock and unlock the entire thing >> . That doesn't seem efficient and/or elegant to me. Any pointers about >> this? > > Do you know about the thread-locking primitives? There are a few kinds > provided by Python's threading module: > > http://www.python.org/doc/lib/module-threading.html > > Are you already familiar with the concept of a RLock or a Lock? > Yup, I'm familiar with those. In all of the examples, I have seen, the critical region happens in one specific area eg a part of a function with a lock and release around it. My question is there a way to lock a specific variable so that even though other functions are attempting to access it, they will not until the first function has released it. Examples below # This example shows the way I have seen it in python tutorials def function1(): blah blah function3() blah blah def function2(): blah blah function3() blah blah def function3(): acquire lock does some stuff release lock t = Thread.thread() t.start(function1()) t.start(function2()) # The way I would like to do it, so we have two different instances of the same variable, and only # one function can access it at a time. If a function comes to that variable and finds a lock on it, # it will wait until the lock is released. And the variable happens to be a queue def function1(): blah blah acquire lock of variable only so that only function1 can access this at a given time ....increment some variable..... release the function2 lock on this variable blah blah def function2(): blah blah acquire lock of variable only so that only function2 can access this at a given time ....decrement some variable...... release the function2 lock on this variable blah blah t = Thread.thread() t.start(function1()) t.start(function2()) Does that make more sense? TIA, Tino _______________________________________________ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
