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Kirill Smelkov
cpython
Commits
2c9f1042
Commit
2c9f1042
authored
Apr 10, 2012
by
Antoine Pitrou
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Fix some markup in the threading docs.
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126aef76
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Doc/library/threading.rst
Doc/library/threading.rst
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Doc/library/threading.rst
View file @
2c9f1042
...
@@ -218,30 +218,31 @@ Thread Objects
...
@@ -218,30 +218,31 @@ Thread Objects
This class represents an activity that is run in a separate thread of control.
This class represents an activity that is run in a separate thread of control.
There are two ways to specify the activity: by passing a callable object to the
There are two ways to specify the activity: by passing a callable object to the
constructor, or by overriding the :meth:`
run` method in a subclass. No other
constructor, or by overriding the :meth:`
~Thread.run` method in a subclass.
methods (except for the constructor) should be overridden in a subclass. In
No other methods (except for the constructor) should be overridden in a
other words, *only* override the :meth:`__init__` and :meth:`run` methods of
subclass. In other words, *only* override the :meth:`~Thread.__init__`
this class.
and :meth:`~Thread.run` methods of
this class.
Once a thread object is created, its activity must be started by calling the
Once a thread object is created, its activity must be started by calling the
thread's :meth:`
start` method. This invokes the :meth:`run` method in a
thread's :meth:`
~Thread.start` method. This invokes the :meth:`~Thread.run`
separate thread of control.
method in a
separate thread of control.
Once the thread's activity is started, the thread is considered 'alive'. It
Once the thread's activity is started, the thread is considered 'alive'. It
stops being alive when its :meth:`
run` method terminates -- either normally, o
r
stops being alive when its :meth:`
~Thread.run` method terminates -- eithe
r
by raising an unhandled exception. The :meth:`is_alive` method tests whether the
normally, or by raising an unhandled exception. The :meth:`~Thread.is_alive`
thread is alive.
method tests whether the
thread is alive.
Other threads can call a thread's :meth:`join` method. This blocks the calling
Other threads can call a thread's :meth:`~Thread.join` method. This blocks
thread until the thread whose :meth:`join` method is called is terminated.
the calling thread until the thread whose :meth:`~Thread.join` method is
called is terminated.
A thread has a name. The name can be passed to the constructor, and read or
A thread has a name. The name can be passed to the constructor, and read or
changed through the :attr:`name` attribute.
changed through the :attr:`
~Thread.
name` attribute.
A thread can be flagged as a "daemon thread". The significance of this flag
is
A thread can be flagged as a "daemon thread". The significance of this flag
that the entire Python program exits when only daemon threads are left. The
is that the entire Python program exits when only daemon threads are left.
initial value is inherited from the creating thread. The flag can be set
The initial value is inherited from the creating thread. The flag can be
through the :attr:`
daemon` property.
set through the :attr:`~Thread.
daemon` property.
There is a "main thread" object; this corresponds to the initial thread of
There is a "main thread" object; this corresponds to the initial thread of
control in the Python program. It is not a daemon thread.
control in the Python program. It is not a daemon thread.
...
@@ -250,8 +251,8 @@ There is the possibility that "dummy thread objects" are created. These are
...
@@ -250,8 +251,8 @@ There is the possibility that "dummy thread objects" are created. These are
thread objects corresponding to "alien threads", which are threads of control
thread objects corresponding to "alien threads", which are threads of control
started outside the threading module, such as directly from C code. Dummy
started outside the threading module, such as directly from C code. Dummy
thread objects have limited functionality; they are always considered alive and
thread objects have limited functionality; they are always considered alive and
daemonic, and cannot be :meth:`
join`\ ed. They are never deleted, since it is
daemonic, and cannot be :meth:`
~Thread.join`\ ed. They are never deleted,
impossible to detect the termination of alien threads.
since it is
impossible to detect the termination of alien threads.
.. class:: Thread(group=None, target=None, name=None, args=(), kwargs={})
.. class:: Thread(group=None, target=None, name=None, args=(), kwargs={})
...
@@ -282,7 +283,8 @@ impossible to detect the termination of alien threads.
...
@@ -282,7 +283,8 @@ impossible to detect the termination of alien threads.
Start the thread's activity.
Start the thread's activity.
It must be called at most once per thread object. It arranges for the
It must be called at most once per thread object. It arranges for the
object's :meth:`run` method to be invoked in a separate thread of control.
object's :meth:`~Thread.run` method to be invoked in a separate thread
of control.
This method will raise a :exc:`RuntimeError` if called more than once
This method will raise a :exc:`RuntimeError` if called more than once
on the same thread object.
on the same thread object.
...
@@ -298,25 +300,27 @@ impossible to detect the termination of alien threads.
...
@@ -298,25 +300,27 @@ impossible to detect the termination of alien threads.
.. method:: join(timeout=None)
.. method:: join(timeout=None)
Wait until the thread terminates. This blocks the calling thread until the
Wait until the thread terminates. This blocks the calling thread until
thread whose :meth:`join` method is called terminates -- either normally
the thread whose :meth:`~Thread.join` method is called terminates -- either
or through an unhandled exception -- or until the optional timeout occurs.
normally or through an unhandled exception --, or until the optional
timeout occurs.
When the *timeout* argument is present and not ``None``, it should be a
When the *timeout* argument is present and not ``None``, it should be a
floating point number specifying a timeout for the operation in seconds
floating point number specifying a timeout for the operation in seconds
(or fractions thereof). As :meth:`join` always returns ``None``, you must
(or fractions thereof). As :meth:`~Thread.join` always returns ``None``,
call :meth:`is_alive` after :meth:`join` to decide whether a timeout
you must call :meth:`~Thread.is_alive` after :meth:`~Thread.join` to
happened -- if the thread is still alive, the :meth:`join` call timed out.
decide whether a timeout happened -- if the thread is still alive, the
:meth:`~Thread.join` call timed out.
When the *timeout* argument is not present or ``None``, the operation will
When the *timeout* argument is not present or ``None``, the operation will
block until the thread terminates.
block until the thread terminates.
A thread can be :meth:`join`\ ed many times.
A thread can be :meth:`
~Thread.
join`\ ed many times.
:meth:`
join` raises a :exc:`RuntimeError` if an attempt is made to join
:meth:`
~Thread.join` raises a :exc:`RuntimeError` if an attempt is made
t
he current thread as that would cause a deadlock. It is also an error t
o
t
o join the current thread as that would cause a deadlock. It is als
o
:meth:`join` a thread before it has been started and attempts to do so
an error to :meth:`~Thread.join` a thread before it has been started
raises
the same exception.
and attempts to do so raise
the same exception.
.. attribute:: name
.. attribute:: name
...
@@ -334,7 +338,7 @@ impossible to detect the termination of alien threads.
...
@@ -334,7 +338,7 @@ impossible to detect the termination of alien threads.
The 'thread identifier' of this thread or ``None`` if the thread has not
The 'thread identifier' of this thread or ``None`` if the thread has not
been started. This is a nonzero integer. See the
been started. This is a nonzero integer. See the
:func:`thread.get_ident()` function. Thread identifiers may be recycled
:func:`
_
thread.get_ident()` function. Thread identifiers may be recycled
when a thread exits and another thread is created. The identifier is
when a thread exits and another thread is created. The identifier is
available even after the thread has exited.
available even after the thread has exited.
...
@@ -342,18 +346,18 @@ impossible to detect the termination of alien threads.
...
@@ -342,18 +346,18 @@ impossible to detect the termination of alien threads.
Return whether the thread is alive.
Return whether the thread is alive.
This method returns ``True`` just before the :meth:`
run` method starts
This method returns ``True`` just before the :meth:`
~Thread.run` method
until just after the :meth:`run` method terminates. The module function
starts until just after the :meth:`~Thread.run` method terminates. The
:func:`.enumerate` returns a list of all alive threads.
module function
:func:`.enumerate` returns a list of all alive threads.
.. attribute:: daemon
.. attribute:: daemon
A boolean value indicating whether this thread is a daemon thread (True)
A boolean value indicating whether this thread is a daemon thread (True)
or not (False). This must be set before :meth:`start` is called,
or not (False). This must be set before :meth:`
~Thread.
start` is called,
otherwise :exc:`RuntimeError` is raised. Its initial value is inherited
otherwise :exc:`RuntimeError` is raised. Its initial value is inherited
from the creating thread; the main thread is not a daemon thread and
from the creating thread; the main thread is not a daemon thread and
therefore all threads created in the main thread default to
:attr:`daemon`
therefore all threads created in the main thread default to
= ``False``.
:attr:`~Thread.daemon`
= ``False``.
The entire Python program exits when no alive non-daemon threads are left.
The entire Python program exits when no alive non-daemon threads are left.
...
@@ -375,19 +379,20 @@ synchronization primitive available, implemented directly by the :mod:`_thread`
...
@@ -375,19 +379,20 @@ synchronization primitive available, implemented directly by the :mod:`_thread`
extension module.
extension module.
A primitive lock is in one of two states, "locked" or "unlocked". It is created
A primitive lock is in one of two states, "locked" or "unlocked". It is created
in the unlocked state. It has two basic methods, :meth:`acquire` and
in the unlocked state. It has two basic methods, :meth:`~Lock.acquire` and
:meth:`release`. When the state is unlocked, :meth:`acquire` changes the state
:meth:`~Lock.release`. When the state is unlocked, :meth:`~Lock.acquire`
to locked and returns immediately. When the state is locked, :meth:`acquire`
changes the state to locked and returns immediately. When the state is locked,
blocks until a call to :meth:`release` in another thread changes it to unlocked,
:meth:`~Lock.acquire` blocks until a call to :meth:`~Lock.release` in another
then the :meth:`acquire` call resets it to locked and returns. The
thread changes it to unlocked, then the :meth:`~Lock.acquire` call resets it
:meth:`release` method should only be called in the locked state; it changes the
to locked and returns. The :meth:`~Lock.release` method should only be
state to unlocked and returns immediately. If an attempt is made to release an
called in the locked state; it changes the state to unlocked and returns
unlocked lock, a :exc:`RuntimeError` will be raised.
immediately. If an attempt is made to release an unlocked lock, a
:exc:`RuntimeError` will be raised.
When more than one thread is blocked in :meth:`acquire` waiting for the state to
turn to unlocked, only one thread proceeds when a :meth:`release` call resets
When more than one thread is blocked in :meth:`~Lock.acquire` waiting for the
the state to unlocked; which one of the waiting threads proceeds is not defined,
state to turn to unlocked, only one thread proceeds when a :meth:`~Lock.release`
and may vary across implementations.
call resets the state to unlocked; which one of the waiting threads proceeds
is not defined, and may vary across implementations.
All methods are executed atomically.
All methods are executed atomically.
...
@@ -446,12 +451,12 @@ and "recursion level" in addition to the locked/unlocked state used by primitive
...
@@ -446,12 +451,12 @@ and "recursion level" in addition to the locked/unlocked state used by primitive
locks. In the locked state, some thread owns the lock; in the unlocked state,
locks. In the locked state, some thread owns the lock; in the unlocked state,
no thread owns it.
no thread owns it.
To lock the lock, a thread calls its :meth:`
acquire` method; this returns once
To lock the lock, a thread calls its :meth:`
~RLock.acquire` method; this
the thread owns the lock. To unlock the lock, a thread calls it
s
returns once the thread owns the lock. To unlock the lock, a thread call
s
:meth:`release` method. :meth:`acquire`/:meth:`release` call pairs may be
its :meth:`~Lock.release` method. :meth:`~Lock.acquire`/:meth:`~Lock.release`
nested; only the final :meth:`release` (the :meth:`release` of the outermost
call pairs may be nested; only the final :meth:`~Lock.release` (the
pair) resets the lock to unlocked and allows another thread blocked in
:meth:`~Lock.release` of the outermost pair) resets the lock to unlocked and
:meth:`
acquire` to proceed.
allows another thread blocked in :meth:`~Lock.
acquire` to proceed.
.. method:: RLock.acquire(blocking=True, timeout=-1)
.. method:: RLock.acquire(blocking=True, timeout=-1)
...
@@ -672,12 +677,14 @@ Semaphore Objects
...
@@ -672,12 +677,14 @@ Semaphore Objects
This is one of the oldest synchronization primitives in the history of computer
This is one of the oldest synchronization primitives in the history of computer
science, invented by the early Dutch computer scientist Edsger W. Dijkstra (he
science, invented by the early Dutch computer scientist Edsger W. Dijkstra (he
used :meth:`P` and :meth:`V` instead of :meth:`acquire` and :meth:`release`).
used the names ``P()`` and ``V()`` instead of :meth:`~Semaphore.acquire` and
:meth:`~Semaphore.release`).
A semaphore manages an internal counter which is decremented by each
A semaphore manages an internal counter which is decremented by each
:meth:`acquire` call and incremented by each :meth:`release` call. The counter
:meth:`~Semaphore.acquire` call and incremented by each :meth:`~Semaphore.release`
can never go below zero; when :meth:`acquire` finds that it is zero, it blocks,
call. The counter can never go below zero; when :meth:`~Semaphore.acquire`
waiting until some other thread calls :meth:`release`.
finds that it is zero, it blocks, waiting until some other thread calls
:meth:`~Semaphore.release`.
.. class:: Semaphore(value=1)
.. class:: Semaphore(value=1)
...
@@ -693,11 +700,12 @@ waiting until some other thread calls :meth:`release`.
...
@@ -693,11 +700,12 @@ waiting until some other thread calls :meth:`release`.
When invoked without arguments: if the internal counter is larger than
When invoked without arguments: if the internal counter is larger than
zero on entry, decrement it by one and return immediately. If it is zero
zero on entry, decrement it by one and return immediately. If it is zero
on entry, block, waiting until some other thread has called
on entry, block, waiting until some other thread has called
:meth:`release` to make it larger than zero. This is done with proper
:meth:`~Semaphore.release` to make it larger than zero. This is done
interlocking so that if multiple :meth:`acquire` calls are blocked,
with proper interlocking so that if multiple :meth:`acquire` calls are
:meth:`release` will wake exactly one of them up. The implementation may
blocked, :meth:`~Semaphore.release` will wake exactly one of them up.
pick one at random, so the order in which blocked threads are awakened
The implementation may pick one at random, so the order in which
should not be relied on. Returns true (or blocks indefinitely).
blocked threads are awakened should not be relied on. Returns
true (or blocks indefinitely).
When invoked with *blocking* set to false, do not block. If a call
When invoked with *blocking* set to false, do not block. If a call
without an argument would block, return false immediately; otherwise,
without an argument would block, return false immediately; otherwise,
...
@@ -753,8 +761,8 @@ This is one of the simplest mechanisms for communication between threads: one
...
@@ -753,8 +761,8 @@ This is one of the simplest mechanisms for communication between threads: one
thread signals an event and other threads wait for it.
thread signals an event and other threads wait for it.
An event object manages an internal flag that can be set to true with the
An event object manages an internal flag that can be set to true with the
:meth:`~Event.set` method and reset to false with the :meth:`
clear` method. The
:meth:`~Event.set` method and reset to false with the :meth:`
~Event.clear`
:meth:`
wait` method blocks until the flag is true.
method. The :meth:`~Event.
wait` method blocks until the flag is true.
.. class:: Event()
.. class:: Event()
...
@@ -781,7 +789,7 @@ An event object manages an internal flag that can be set to true with the
...
@@ -781,7 +789,7 @@ An event object manages an internal flag that can be set to true with the
Block until the internal flag is true. If the internal flag is true on
Block until the internal flag is true. If the internal flag is true on
entry, return immediately. Otherwise, block until another thread calls
entry, return immediately. Otherwise, block until another thread calls
:meth:`set` to set the flag to true, or until the optional timeout occurs.
:meth:`
.
set` to set the flag to true, or until the optional timeout occurs.
When the timeout argument is present and not ``None``, it should be a
When the timeout argument is present and not ``None``, it should be a
floating point number specifying a timeout for the operation in seconds
floating point number specifying a timeout for the operation in seconds
...
@@ -837,8 +845,8 @@ Barrier Objects
...
@@ -837,8 +845,8 @@ Barrier Objects
This class provides a simple synchronization primitive for use by a fixed number
This class provides a simple synchronization primitive for use by a fixed number
of threads that need to wait for each other. Each of the threads tries to pass
of threads that need to wait for each other. Each of the threads tries to pass
the barrier by calling the :meth:`
wait` method and will block until all of the
the barrier by calling the :meth:`
~Barrier.wait` method and will block until
threads have made the call. At this points, the threads are released
all of the
threads have made the call. At this points, the threads are released
simultanously.
simultanously.
The barrier can be reused any number of times for the same number of threads.
The barrier can be reused any number of times for the same number of threads.
...
...
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