uuid.uuid1、uuid_generate_time 和线程

Question

在Python中，我发现可以通过在多个线程中反复调用uuid.uuid1()来产生一个段错误（seg fault）。经过一些调查，这个函数最终通过ctypes调用了C语言中的uuid_generate_time函数。

在uuid.py文件中：

for libname in ['uuid', 'c']:
    try:
        lib = ctypes.CDLL(ctypes.util.find_library(libname))
    except:
        continue
    if hasattr(lib, 'uuid_generate_random'):
        _uuid_generate_random = lib.uuid_generate_random
    if hasattr(lib, 'uuid_generate_time'):
        _uuid_generate_time = lib.uuid_generate_time
        if _uuid_generate_random is not None:
            break  # found everything we were looking for

然后在uuid1()的定义中：

def uuid1(node=None, clock_seq=None):
    """Generate a UUID from a host ID, sequence number, and the current time.
    If 'node' is not given, getnode() is used to obtain the hardware
    address.  If 'clock_seq' is given, it is used as the sequence number;
    otherwise a random 14-bit sequence number is chosen."""

    # When the system provides a version-1 UUID generator, use it (but don't
    # use UuidCreate here because its UUIDs don't conform to RFC 4122).
    if _uuid_generate_time and node is clock_seq is None:
        _buffer = ctypes.create_string_buffer(16)
        _uuid_generate_time(_buffer)
        return UUID(bytes=_buffer.raw)

我查阅了uuid_generate_time的手册以及Python文档中的uuid.uuid1，但没有看到关于线程安全的说明。我猜这可能和它需要访问系统时钟和/或MAC地址有关，但这只是我的一个盲目猜测。

我想知道有没有人能给我一些启发？

以下是我用来产生段错误的代码：

import threading, uuid

# XXX If I use a lock, I can avoid the seg fault
#uuid_lock = threading.Lock()
def test_uuid(test_func):
  for i in xrange(100):
    test_func()
    #with uuid_lock:
    #  test_func()

def test(test_func, threads):
  print 'Running %s with %s threads...' % (test_func.__name__, threads)

  workers = [threading.Thread(target=test_uuid, args=(test_func,)) for x in xrange(threads)]
  [x.start() for x in workers]
  [x.join() for x in workers]
  print 'Done!'

if __name__ == '__main__':
  test(uuid.uuid4, 8)
  test(uuid.uuid1, 8)

我得到的输出是：

Running uuid4 with 8 threads...
Done!
Running uuid1 with 8 threads...
Segmentation Fault (core dumped)

哦，对了，我是在Solaris系统上运行这个的……

threading uuid concurrency solaris thread safety segmentation fault system clock mac address

uuid.uuid1、uuid_generate_time 和线程

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