thanks - I expected that the api calls would use parallel processing, but the app/servelet itself is a single thread of execution. if I have api_cpu_ms of 74, and cpu_ms of 1500, then that gives 1426ms for the non-api (app/servelet usage), yes? I'm trying to grok how that would happen in a single thread in 965ms of wall-clock time.
Jeff On Mon, Aug 31, 2009 at 11:30 AM, Jeff S (Google)<j...@google.com> wrote: > Hi Jeff > > On Fri, Aug 28, 2009 at 1:08 AM, Jeff Enderwick <jeff.enderw...@gmail.com> > wrote: >> >> Trolling my logs, I'm coming across cases where there is extreme >> (~10x) variance in cpu_ms for the exact same code flow, same GET URL >> and same data (not even any intervening writes to the datastore). I am >> logging my db.* function accesses, and I have factored out memcache >> too. For example: >> >> 92ms, 142cpu_ms, 74api_cpu_ms, followed by: >> 965ms, 1500cpu_ms, 74api_cpu_ms >> >> Q1: what could cause such a whopping delta? I am using Django, so >> perhaps template compilation? I used cprofile on the SDK with a >> similar data/result set, and the first page served was maybe ~2x >> subsequent pages in total time. Thoughts? > > Your idea of template compilation is along the same lines as my thinking. I > can't say difinitively for this case but I would guess that you might be > seeing a more expensive first request when a new instance of you app is > being spun up. > >> >> Q2: I am assuming the 1st number after the '200' is the wall-clock >> time-to-server. As the app is single threaded ... how is it able to >> burn 1500ms less 74ms in only 965ms? > > Most API calls make calls to distributed services which parallelize work > across multiple machines, so it often easy to use more CPU time than wall > clock time. If you want to see where the CPU usage is coming from, you can > get information about CPU quota levels at any point within your code as > documented here: > > http://code.google.com/appengine/docs/quotas.html#Monitoring_CPU_Usage_in_a_Request > > Thank you, > > Jeff > >> >> Thanks! >> >> > > > > > --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
