A simple application, which is running at the google app engine,
visits the datastore, and uses the urlfetch service as well. I want
to add the 6 hooks into the code to get the timestamp when code is
running at that checkpoint, thus the transactions performance
profiling can be done by calculating with the timestamps.
Here's the flow in pseudo code:
class MainPage(webapp.RequestHandler):
def get(self):
--> 1. hook at program starting
do something ...
--> 2. hook before fetching url
result = urlfetch.fetch(url="http://...";)
--> 3. hook after fetching url
do something ...
--> 4. hook before visiting datastore
visit datastore
--> 5. hook after visiting datastore
do something
--> 6. finish hook
Although it's straightforward to just add the hook code in the
original code, however, in order to minimize the modification to
existing code, I use the following approaches:
1. Use "apiproxy_stub_map.apiproxy.GetPreCallHooks().Append" to add
hooks to get data at checkpoint 2, 3, 4, 5. I referenced the article
http://code.google.com/appengine/articles/hooks.html
2. Monkeypatch google.appengine.ext.webapp.WSGIApplication (assuming
the original code is written with webapp framework) by overwritting
def __call__(self, environ, start_response). I just add my code
before and after calling the real method. Therefore, I can get data
at checkpoint 1 and 6. The orignial code just need to modified to
use the subclass of WSGIApplication.
Here's the problem I run into.
Since multiple users might be visiting the same application at the
sametime, in order not to mess up data from different users, we must
be able to get a same id, such as thread id for the 6 checkpoints of
each user. However, I cannot achieve this.
I have tried to use thread.get_ident(), but it always returns -1. (I
know google app engine doesn't allow create new thread, but it doesn't
make any sense to return -1 for threads created by google engine
itself ...)
I tried to store some data at the thread local objects pool (just as I
do with Java), but seems the thread.local is not the same with the one
in Java. I'm not familiar with python anyway, maybe I miss
something or misunderstand something.
Do you guys have any idea about this? Thanks very much in advance!
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Google App Engine" group.
To post to this group, send email to [email protected]
To unsubscribe from this group, send email to
[email protected]
For more options, visit this group at
http://groups.google.com/group/google-appengine?hl=en
-~----------~----~----~----~------~----~------~--~---
