pydev多线程调试

Question

我正在尝试调试一个使用pynetdicom库的应用程序。我不确定这个具体细节有多相关，但相关的是它大量使用多线程来运行后台套接字侦听器任务，而不阻塞主线程。可以使用storescp.py示例来再现此示例。

每当我放置遇到的断点(不管哪个线程、main或子线程在其中遇到)，我都会得到以下跟踪：

Traceback (most recent call last):
  File "/Applications/Aptana Studio 3/plugins/org.python.pydev_2.7.0.2013012902/pysrc/pydevd.py", line 1397, in <module>
    debugger.run(setup['file'], None, None)
  File "/Applications/Aptana Studio 3/plugins/org.python.pydev_2.7.0.2013012902/pysrc/pydevd.py", line 1090, in run
    pydev_imports.execfile(file, globals, locals) #execute the script
  File "/Users/alexw/Development/Python/kreport2/KReport2/dicomdatascraper.py", line 183, in <module>
    oldDicomList = copy.copy(newData)
  File "/Users/alexw/Development/Python/kreport2/KReport2/dicomdatascraper.py", line 183, in <module>
    oldDicomList = copy.copy(newData)
  File "/Applications/Aptana Studio 3/plugins/org.python.pydev_2.7.0.2013012902/pysrc/pydevd_frame.py", line 135, in trace_dispatch
    self.doWaitSuspend(thread, frame, event, arg)
  File "/Applications/Aptana Studio 3/plugins/org.python.pydev_2.7.0.2013012902/pysrc/pydevd_frame.py", line 25, in doWaitSuspend
    self._args[0].doWaitSuspend(*args, **kwargs)
  File "/Applications/Aptana Studio 3/plugins/org.python.pydev_2.7.0.2013012902/pysrc/pydevd.py", line 832, in doWaitSuspend
    self.processInternalCommands()
  File "/Applications/Aptana Studio 3/plugins/org.python.pydev_2.7.0.2013012902/pysrc/pydevd.py", line 360, in processInternalCommands
    thread_id = GetThreadId(t)
  File "/Applications/Aptana Studio 3/plugins/org.python.pydev_2.7.0.2013012902/pysrc/pydevd_constants.py", line 140, in GetThreadId
    return thread.__pydevd_id__
  File "/Users/alexw/.virtualenvs/kreport2dev/devlibs/pynetdicom/source/netdicom/applicationentity.py", line 73, in __getattr__
    obj = eval(attr)()
  File "<string>", line 1, in <module>
NameError: name '__pydevd_id__' is not defined

我的想法是，也许为了使事情正常运行，PyDev猴子将一个__pydevd_id__补丁到生成的线程中，但是没有将它们修补到这些线程中，因为它们实际上是threading.Thread的子类，而不是直接的threading.Thread实例(在本例中，工作人员是class Association(threading.Thread):的一个实例)。

当然，我对PyDev的了解还不足以证实这一理论，否则我就会修正它。互联网似乎也是如此。

子类Thread是否很少使用，以致于在PyDev体系结构中根本没有考虑到它？如果不重新设计库，如何解决这个问题？

Answer 1

我只需要更努力地寻找回溯。

在对threading.Thread的子类中，pynetdicom库覆盖了__getattr__，并对其进行了一些破坏。问题是：

def __getattr__(self, attr):
    #while not self.AssociationEstablished:
    #    time.sleep(0.001)
    obj = eval(attr)

    # do some stuff

    return obj

当传递不存在的属性时，将引发NameError。这不是被pydev的猴击程序(if thread.__pydevd_id__ raises AttributeError, thread.__pydevd_id__ = stuff)捕获的。

解决办法是更新这一节：

def __getattr__(self, attr):
    #while not self.AssociationEstablished:
    #    time.sleep(0.001)
    try:
        obj = eval(attr)
    except NameError:
        raise AttributeError

    # do some stuff

    return obj

这将拦截NameError并引发一个AttributeError，如果查询的属性不存在，__getattr__就应该这样做。