You are correct, executing a URL Fetch request during the initiation of your code will cause a large amount of latency as your instance must wait for the requesting server to respond. As previously mentioned you can use the Stackdriver Trace <https://cloud.google.com/trace/> tool on a specific '/_ah/warmup' request that is seeing high latency to investigate the exact parts of your code that are taking up the most time.
Using this same tool I went ahead and took a look at your project. I saw that on 2016-10-22 a single '/urlfetch.Fetch' took 47.5 seconds to return in one of your '/_ah/warmup' instance startups. I also saw a single request to your endpoint '/api/admin/warmup' took 62 seconds, and 56 '/datastore_v3.Put' calls took a combined 2 seconds, all during the same instance startup. These results were quickly pulled from the 'Summary' tab in the trace details <https://cloud.google.com/trace/docs/viewing-details> for one of your calls. Concerning the latency comparison of running your app in production vs locally in development. While running locally your application and all of its assets lives within a local web server on your computer. This web server is hosted on your same localhost IP, meaning any outgoing requests will be instantly served by your same computer. This differs from production in that any URL Fetch request or API call needs to be served from a different location by a different server, bringing network latency and the traffic congestion of each server into the mix. You can easily see from the above how removing URL Fetch requests and batching your requests to Google Services would drastically reduce the startup time for your instances. -- You received this message because you are subscribed to the Google Groups "Google App Engine" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/google-appengine. To view this discussion on the web visit https://groups.google.com/d/msgid/google-appengine/f1a781ea-3664-41af-992c-6bcf6320f438%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
