Hi Liang Han, (Replies inline)
On Thu, Jun 11, 2009 at 2:15 AM, Liang Han <liang....@gmail.com> wrote: > > 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. Cool stuff you're working on! Are you planning on releasing it for others to use? > > > 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. App Engine apps run in a single-threaded environment. That is, a given interpreter instance will only ever be processing one request at any given time. Thus, you don't need to worry about concurrent invocations. -Nick Johnson > > > 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 google-appengine@googlegroups.com To unsubscribe from this group, send email to google-appengine+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en -~----------~----~----~----~------~----~------~--~---
