Issues with Appengine

I like App Engine, my wedding website runs on App Engine as well as a couple recent commercial projects.  However, there are some annoyances that make a lot of the useful things I learned at Google not applicable.

1. Chunked responses
   App Engine doesn't have a way of doing chunked responses.
   1.5. Processing after sending the response My annoyance here is that I can't send an early response and wait for some resource.  Say I want to do 5 url fetches that I cache for a short period of time.  If I want to reply in 250ms, I want to use any of the results I've gotten and reply to the user.  Then once the rest of the fetches come in, I want to put them in the cache, so they will come back quickly the next time.
2. Counters
   App Engine has crappy support for counters.  You can shard your counters into the datastore: https://developers.google.com/appengine/articles/sharding_counters#counter_python or you can use taskqueues: http://blog.appenginefan.com/2009/10/non-sharded-counters-part-2-using-task.html .   Now, how do you graph these counters over time, well, that is left as an exercise for the reader.  Google has special datastores for stores and retrieving counters.
3. Backends
   Backends in appengine are versioned separately from frontends.  This sounds like a good idea, but to run the devserver with backends, the backends need to be in the same source tree.  Thus backends share the same url space.  Backends also share the same app.yaml, so again the url space is shared.  Thus, if you make a change that you want to coordinate between the frontend and the backend, you need to change the application version in app.yaml, then rename all the backends in backends.yaml.   If backends are supposed to be in the same source tree as frontends, then they should be prefixed with the application version.  If backends should be versioned separately from frontends, then they shouldn't share url handlers from app.yaml.
   3.5 Uploading backends is slow
   Each backend is uploaded through appcfg.py separately.  So if you are crazy and have one backend per backend level, then you need to upload 4 copies of the source code each time the backends get updated.
4. Logging
   I want structured logs.  Instead what you have to do is use the python logging module to write out human readable logs, then parse them out into the structure you want.
   http://code.google.com/p/google-app-engine-samples/source/browse/trunk/logparser/logparser.py
   

As a preemptive counter, 1.5 could be dealt with using backends and a background thread, except backends don't scale to the number of queries, so my use case above isn't fixed.