带有Python 2.7的Google App Engine中的线程

Question

I have an application that was runing with threads in Python 2.5 in GAE. In the last month I have updated it to Python 2.7 and the threads have stoped to work. I have search on Google and here to see if there is a problem now with the threads in GAE with Python 2.7, but I have not found anything.

The code is the following:

def post(self):

    bloqueo = thread.allocate_lock()
    bloqueo.acquire()
    thread.start_new_thread(self.principal,(bloqueo,))

def principal (self,bloqueo):

    bloqueo.acquire()

When I run the code, it stops at thread.start_new_thread(self.principal,(bloqueo,)) and gives the following error:

Thread running after request. Creation traceback:
File "/base/data/home/runtimes/python27/python27_lib/versions/1/google/appengine/runtime/runtime.py", line 151, in HandleRequest
error)
File "/base/data/home/runtimes/python27/python27_lib/versions/1/google/appengine/runtime/wsgi.py", line 328, in HandleRequest
return WsgiRequest(environ, handler_name, url, post_data, error).Handle()
File "/base/data/home/runtimes/python27/python27_lib/versions/1/google/appengine/runtime/wsgi.py", line 266, in Handle
result = handler(dict(self._environ), self._StartResponse)
File "/base/data/home/runtimes/python27/python27_lib/versions/third_party/webapp2-2.5.2/webapp2.py", line 1529, in __call__
rv = self.router.dispatch(request, response)
File "/base/data/home/runtimes/python27/python27_lib/versions/third_party/webapp2-2.5.2/webapp2.py", line 1278, in default_dispatcher
return route.handler_adapter(request, response)
File "/base/data/home/runtimes/python27/python27_lib/versions/third_party/webapp2-2.5.2/webapp2.py", line 1102, in __call__
return handler.dispatch()
File "/base/data/home/runtimes/python27/python27_lib/versions/third_party/webapp2-2.5.2/webapp2.py", line 570, in dispatch
return method(*args, **kwargs)
File "/base/data/home/apps/s~applcation/8.374533192190096875/src/arc.py", line 1938, in post
thread.start_new_thread(self.principal,(bloqueo,))
File "/base/data/home/runtimes/python27/python27_lib/versions/1/google/appengine/runtime/runtime.py", line 81, in StartNewThread
return base_start_new_thread(Run, ())

Do you know which one is the problem and how to solve it?

Thank you

Answer 1

threading was never supported in appengine under the python2.5 runtime.

It was only introduced with Python2.7 support. So I don't see how this code could possibly have run in appengine with 2.5 runtime.

See docs

https://developers.google.com/appengine/docs/python/python25/diff27

Also I can't possibly see why you would need threads for front end requests but thats a seperate issue.

If we look at the specific error you have, it says "Thread running after request. Creation traceback:"

This means you are trying to continue running the thread after you have returned from the request handler. You can not do this with appengine. You must wait for any threads to finish and then return. In the main performing work with a thread in a front facing request just over complicates things. If you want some concurrency in a front facing request you should use async operations. Certainly what you are trying to do will never work and won't improve performance in any way.

In addition trying to use locks won't help at all if another instance is handling the same request at the same time. That is what transactions are for.

Despite the small amount of information you provided so far, I really feel you should drop the threads altogether.