Re: [google-appengine] Re: ~20ms latency between two servlets, same project, is that about right?

[Eric Hubbard]

Thanks for the great info!

I'm running standard and java8.  My latency times were much lower 24 hours
later.  I went from a chaotic..20-50ms...   down to a very stable ~12ms 24
hours later.  Maybe some  environmental things were going at at the time.
These numbers were reported by my code, and also seen by the log traces.




-Eric
http://www.google.com/profiles/eric.hubbard

On Tue, Aug 29, 2017 at 11:03 AM, 'Jordan (Cloud Platform Support)' via
Google App Engine  wrote:

> It really depends on if you are making calls within App Engine Standard
>  or App Engine Flexible
>  as they both
> send/accept requests using different infrastructures.
>
> - The App Engine Standard URLFetch infrastructure typically adds less than
> 1 ms latency overhead to HTTP requests. For URLFetch requests to other App
> Engine Standard services, I am seeing worst case ~8ms of latency in the
> 95th percentile (meaning 95 percent of URLFetch requests are under 8ms).
> Note that we do not guarantee any specific SLA on latency.
>
> - The App Engine Flexible environment uses Compute Engine
>  virtual machines that are behind
> their own gateway. I am seeing ~20ms serving latency for Flex apps in the
> US at the 99th percentile (meaning 99 percent of requests are under 20ms).
>
> There are many factors in App Engine that can be slowing down your ping,
> such as instance startup time (based on your code and runtime), scaling
> settings
> ,
> and instance class
> .
> Also your actual coding language adds to the ping time while it
> accepts/processes/and returns the request. Therefore, to get a more
> accurate ping for only the service-to-service communication time, you
> should do it by looking at the actual time your App Engine service accepted
> the request in the Logs Viewer
> .
>
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[google-appengine] ~20ms latency between two servlets, same project, is that about right?

[Eric Hubbard]

Playing around with splitting my project up into separate services, and 
invoking via URLFetch between them.  I'm seeing anywhere from a 20-22ms 
latency on a very basic remote side side.  I'm using Kotlin compiled down 
to java8.   (the ping servlet is in java8...)... 

So.. does ~20ms seem about right? 



val fetchOptions =FetchOptions.Builder.doNotFollowRedirects()
val instanceHostname =getInstanceHostname("default", "1", "$serverNum")
val u = URL("http://$instanceHostname/ping";)
val req = HTTPRequest(u, HTTPMethod.GET, fetchOptions)
val timer = Stopwatch.createStarted()
val fetch = urlFetchService.fetch(req)
val rc = fetch.responseCode
timer.stop()


and then this in the /ping servlet


protected void doGet(HttpServletRequest request, HttpServletResponse response) 
throws ServletException, IOException {
PrintWriter writer = response.getWriter();
writer.println("Hello there from the backend");
writer.flush();
}

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