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javaprometheusmetricslatency

Interpreting Prometheus query result

My first question has been answered. Now I am trying to interpret the results based on the given query.

METRIC ACQUISITION:

// globally done
Summary.build()
       .name("http_response_time")
       .labelNames("method", "handler", "status")
       .help("Request completed")
       .register();

// done BEFORE every request
final long start = System.nanoTime();
// "start" is saved as a request attribute and lateron read from the request

// done AFTER every request
final double latencyInSeconds =
   SimpleTimer.elapsedSecondsFromNanos(start, System.nanoTime());

responseTime.labels(
   request.getMethod(),
   handlerLabel,
   String.valueOf(response.getStatus())
)
.observe(latencyInSeconds);

QUERY:

rate(http_response_time_sum{application="myapp",handler="myHandler", status="200"}[1m])
/
rate(http_response_time_count{application="myapp",handler="myHandler", status="200"}[1m])

RESULT:

0.0020312920780360694

So, what is this? Measured in ns, pushed to summary object in seconds.

As far as I would interpret it, this tells me that all successful requests of the last minute have an average latency of 0.0020 seconds (20ms).

Is that correct?

Solution

  • I will post my results here: the measured/calculated/interpreted value seems to be correct.

    Anyway, I would prefer a more detailed and mathematical documentation of the Prometheus methods.