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(python2.1-lib.info)threading

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Higher-level threading interface
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Higher-level threading interface.

This module constructs higher-level threading interfaces on top of the
lower level `thread' module.

This module is safe for use with `from threading import *'.  It defines
the following functions and objects:

`activeCount()'
     Return the number of currently active `Thread' objects.  The
     returned count is equal to the length of the list returned by
     `enumerate()'.  A function that returns the number of currently
     active threads.

`Condition()'
     A factory function that returns a new condition variable object.
     A condition variable allows one or more threads to wait until they
     are notified by another thread.

`currentThread()'
     Return the current `Thread' object, corresponding to the caller's
     thread of control.  If the caller's thread of control was not
     created through the `threading' module, a dummy thread object with
     limited functionality is returned.

`enumerate()'
     Return a list of all currently active `Thread' objects.  The list
     includes daemonic threads, dummy thread objects created by
     `currentThread()', and the main thread.  It excludes terminated
     threads and threads that have not yet been started.

`Event()'
     A factory function that returns a new event object.  An event
     manages a flag that can be set to true with the `set()' method and
     reset to false with the `clear()' method.  The `wait()' method
     blocks until the flag is true.

`Lock()'
     A factory function that returns a new primitive lock object.  Once
     a thread has acquired it, subsequent attempts to acquire it block,
     until it is released; any thread may release it.

`RLock()'
     A factory function that returns a new reentrant lock object.  A
     reentrant lock must be released by the thread that acquired it.
     Once a thread has acquired a reentrant lock, the same thread may
     acquire it again without blocking; the thread must release it once
     for each time it has acquired it.

`Semaphore()'
     A factory function that returns a new semaphore object.  A
     semaphore manages a counter representing the number of `release()'
     calls minus the number of `acquire()' calls, plus an initial value.
     The `acquire()' method blocks if necessary until it can return
     without making the counter negative.

`Thread'
     {} A class that represents a thread of control.  This class can be
     safely subclassed in a limited fashion.

Detailed interfaces for the objects are documented below.

The design of this module is loosely based on Java's threading model.
However, where Java makes locks and condition variables basic behavior
of every object, they are separate objects in Python.  Python's `Thread'
class supports a subset of the behavior of Java's Thread class;
currently, there are no priorities, no thread groups, and threads
cannot be destroyed, stopped, suspended, resumed, or interrupted.  The
static methods of Java's Thread class, when implemented, are mapped to
module-level functions.

All of the methods described below are executed atomically.

Lock Objects

RLock Objects

Condition Objects

Semaphore Objects

Event Objects

Thread Objects