Issue #7316: the acquire() method of lock objects in the :mod:`threading`

module now takes an optional timeout argument in seconds.  Timeout support
relies on the system threading library, so as to avoid a semi-busy wait
loop.

1 files changed, 23 insertions, 8 deletions

diff --git a/Doc/library/_thread.rst b/Doc/library/_thread.rst
index cb624078ca..d4ff6dead1 100644
--- a/Doc/library/_thread.rst
+++ b/Doc/library/_thread.rst
@@ -28,7 +28,7 @@ implementation.  For systems lacking the :mod:`_thread` module, the
 :mod:`_dummy_thread` module is available. It duplicates this module's interface
 and can be used as a drop-in replacement.
 
-It defines the following constant and functions:
+It defines the following constants and functions:
 
 
 .. exception:: error
@@ -103,19 +103,34 @@ It defines the following constant and functions:
    Availability: Windows, systems with POSIX threads.
 
 
+.. data:: TIMEOUT_MAX
+
+   The maximum value allowed for the *timeout* parameter of
+   :meth:`Lock.acquire`. Specifiying a timeout greater than this value will
+   raise an :exc:`OverflowError`.
+
+
 Lock objects have the following methods:
 
 
-.. method:: lock.acquire([waitflag])
+.. method:: lock.acquire(waitflag=1, timeout=-1)
 
-   Without the optional argument, this method acquires the lock unconditionally, if
+   Without any optional argument, this method acquires the lock unconditionally, if
    necessary waiting until it is released by another thread (only one thread at a
-   time can acquire a lock --- that's their reason for existence).  If the integer
-   *waitflag* argument is present, the action depends on its value: if it is zero,
-   the lock is only acquired if it can be acquired immediately without waiting,
-   while if it is nonzero, the lock is acquired unconditionally as before.  The
-   return value is ``True`` if the lock is acquired successfully, ``False`` if not.
+   time can acquire a lock --- that's their reason for existence).
 
+   If the integer *waitflag* argument is present, the action depends on its
+   value: if it is zero, the lock is only acquired if it can be acquired
+   immediately without waiting, while if it is nonzero, the lock is acquired
+   unconditionally as above.
+
+   If the floating-point *timeout* argument is present and positive, it
+   specifies the maximum wait time in seconds before returning.  A negative
+   *timeout* argument specifies an unbounded wait.  You cannot specify
+   a *timeout* if *waitflag* is zero.
+
+   The return value is ``True`` if the lock is acquired successfully,
+   ``False`` if not.
 
 .. method:: lock.release()