AlFire <[EMAIL PROTECTED]> wrote:
> But I still can not believe that +=1 is not a thread safe operation.
>
>
> Any clue?
The statement:
x+=1
is equivalent to:
x = x.__iadd__(1)
i.e. a function call followed by an assignment.
If the object is mutable then this *may* be safe so long as you never do
any other assignment to x (the __iadd__ method will return the object being
mutated so the assignment would in this restricted case be a noop).
Integers are immutable, so the assignment must always rebind x to a new
object. There is no way given Python's semantics that this could be thread
safe.
Generating hundreds of threads is, BTW, a very good way to get poor
performance on any system. Don't do that. Create a few threads and put the
actions for those threads into a Queue. If you want the threads to execute
in parallel investigate using sub-processes.
The threading module already has a function to return the number of Thread
objects currently alive.
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