python线程锁
我最近的python学习计划就是把python的线程锁搞清楚。
锁这种东西：数据库有数据库锁，文件也有文件锁（这是在数据库层次，或者操作系统层次实现）。
python内部的锁是在共享资源时候的一种保护（其本质可能也是c或者其他的实现，但原理是相似的，就是防止冲突式访问）。
下面的代码出自thread.py
# encoding: utf-8 # module thread # from (built-in) # by generator 1.143 """ This module provides primitive operations to write multi-threaded programs. The 'threading' module provides a more convenient interface. """ # no imports # functions def allocate(): # real signature unknown; restored from __doc__ """ allocate_lock() -> lock object (allocate() is an obsolete synonym) Create a new lock object. See help(LockType) for information about locks. """ pass def allocate_lock(): # real signature unknown; restored from __doc__ """ allocate_lock() -> lock object (allocate() is an obsolete synonym) Create a new lock object. See help(LockType) for information about locks. """ pass def exit(): # real signature unknown; restored from __doc__ """ exit() (exit_thread() is an obsolete synonym) This is synonymous to ``raise SystemExit''. It will cause the current thread to exit silently unless the exception is caught. """ pass def exit_thread(): # real signature unknown; restored from __doc__ """ exit() (exit_thread() is an obsolete synonym) This is synonymous to ``raise SystemExit''. It will cause the current thread to exit silently unless the exception is caught. """ pass def get_ident(): # real signature unknown; restored from __doc__ """ get_ident() -> integer Return a non-zero integer that uniquely identifies the current thread amongst other threads that exist simultaneously. This may be used to identify per-thread resources. Even though on some platforms threads identities may appear to be allocated consecutive numbers starting at 1, this behavior should not be relied upon, and the number should be seen purely as a magic cookie. A thread's identity may be reused for another thread after it exits. """ return 0 def interrupt_main(): # real signature unknown; restored from __doc__ """ interrupt_main() Raise a KeyboardInterrupt in the main thread. A subthread can use this function to interrupt the main thread. """ pass def stack_size(size=None): # real signature unknown; restored from __doc__ """ stack_size([size]) -> size Return the thread stack size used when creating new threads. The optional size argument specifies the stack size (in bytes) to be used for subsequently created threads, and must be 0 (use platform or configured default) or a positive integer value of at least 32,768 (32k). If changing the thread stack size is unsupported, a ThreadError exception is raised. If the specified size is invalid, a ValueError exception is raised, and the stack size is unmodified. 32k bytes currently the minimum supported stack size value to guarantee sufficient stack space for the interpreter itself. Note that some platforms may have particular restrictions on values for the stack size, such as requiring a minimum stack size larger than 32kB or requiring allocation in multiples of the system memory page size - platform documentation should be referred to for more information (4kB pages are common; using multiples of 4096 for the stack size is the suggested approach in the absence of more specific information). """ pass def start_new(function, args, kwargs=None): # known case of thread.start_new """ start_new_thread(function, args[, kwargs]) (start_new() is an obsolete synonym) Start a new thread and return its identifier. The thread will call the function with positional arguments from the tuple args and keyword arguments taken from the optional dictionary kwargs. The thread exits when the function returns; the return value is ignored. The thread will also exit when the function raises an unhandled exception; a stack trace will be printed unless the exception is SystemExit. """ return 0 def start_new_thread(function, args, kwargs=None): # real signature unknown; restored from __doc__ """ start_new_thread(function, args[, kwargs]) (start_new() is an obsolete synonym) Start a new thread and return its identifier. The thread will call the function with positional arguments from the tuple args and keyword arguments taken from the optional dictionary kwargs. The thread exits when the function returns; the return value is ignored. The thread will also exit when the function raises an unhandled exception; a stack trace will be printed unless the exception is SystemExit. """ pass def _count(): # real signature unknown; restored from __doc__ """ _count() -> integer Return the number of currently running Python threads, excluding the main thread. The returned number comprises all threads created through `start_new_thread()` as well as `threading.Thread`, and not yet finished. This function is meant for internal and specialized purposes only. In most applications `threading.enumerate()` should be used instead. """ return 0 # classes class error(Exception): # no doc def __init__(self, *args, **kwargs): # real signature unknown pass __weakref__ = property(lambda self: object(), lambda self, v: None, lambda self: None) # default """list of weak references to the object (if defined)""" class LockType(object): """ A lock object is a synchronization primitive. To create a lock, call the PyThread_allocate_lock() function. Methods are: acquire() -- lock the lock, possibly blocking until it can be obtained release() -- unlock of the lock locked() -- test whether the lock is currently locked A lock is not owned by the thread that locked it; another thread may unlock it. A thread attempting to lock a lock that it has already locked will block until another thread unlocks it. Deadlocks may ensue. """ def acquire(self, wait=None): # real signature unknown; restored from __doc__ """ acquire([wait]) -> bool (acquire_lock() is an obsolete synonym) Lock the lock. Without argument, this blocks if the lock is already locked (even by the same thread), waiting for another thread to release the lock, and return True once the lock is acquired. With an argument, this will only block if the argument is true, and the return value reflects whether the lock is acquired. The blocking operation is not interruptible. """ return False def acquire_lock(self): # real signature unknown; restored from __doc__ """ acquire([wait]) -> bool (acquire_lock() is an obsolete synonym) Lock the lock. Without argument, this blocks if the lock is already locked (even by the same thread), waiting for another thread to release the lock, and return True once the lock is acquired. With an argument, this will only block if the argument is true, and the return value reflects whether the lock is acquired. The blocking operation is not interruptible. """ pass def locked(self): # real signature unknown; restored from __doc__ """ locked() -> bool (locked_lock() is an obsolete synonym) Return whether the lock is in the locked state. """ return False def locked_lock(self): # real signature unknown; restored from __doc__ """ locked() -> bool (locked_lock() is an obsolete synonym) Return whether the lock is in the locked state. """ pass def release(self): # real signature unknown; restored from __doc__ """ release() (release_lock() is an obsolete synonym) Release the lock, allowing another thread that is blocked waiting for the lock to acquire the lock. The lock must be in the locked state, but it needn't be locked by the same thread that unlocks it. """ pass def release_lock(self): # real signature unknown; restored from __doc__ """ release() (release_lock() is an obsolete synonym) Release the lock, allowing another thread that is blocked waiting for the lock to acquire the lock. The lock must be in the locked state, but it needn't be locked by the same thread that unlocks it. """ pass def __enter__(self, *args, **kwargs): # real signature unknown """ acquire([wait]) -> bool (acquire_lock() is an obsolete synonym) Lock the lock. Without argument, this blocks if the lock is already locked (even by the same thread), waiting for another thread to release the lock, and return True once the lock is acquired. With an argument, this will only block if the argument is true, and the return value reflects whether the lock is acquired. The blocking operation is not interruptible. """ pass def __exit__(self, *args, **kwargs): # real signature unknown """ release() (release_lock() is an obsolete synonym) Release the lock, allowing another thread that is blocked waiting for the lock to acquire the lock. The lock must be in the locked state, but it needn't be locked by the same thread that unlocks it. """ pass def __init__(self, *args, **kwargs): # real signature unknown pass class _local(object): """ Thread-local data """ def __delattr__(self, name): # real signature unknown; restored from __doc__ """ x.__delattr__('name') <==> del x.name """ pass def __getattribute__(self, name): # real signature unknown; restored from __doc__ """ x.__getattribute__('name') <==> x.name """ pass def __init__(self, *args, **kwargs): # real signature unknown pass @staticmethod # known case of __new__ def __new__(S, *more): # real signature unknown; restored from __doc__ """ T.__new__(S, ...) -> a new object with type S, a subtype of T """ pass def __setattr__(self, name, value): # real signature unknown; restored from __doc__ """ x.__setattr__('name', value) <==> x.name = value """ pass