Overhead

Overhead is so minimal that it is difficult to measure on most applications where the overhead gets lost in the run-to-run variance.

We have to use super fast microservices with response times in the microseconds in order to reliably detect and measure Glowroot's overhead.

The benchmark below is run against a very fast dropwizard-based microservice (benchmarking is performed using the excellent JMH).

	Baseline	with Glowroot	Overhead
Response times
Average	80.0 μs	82.9 μs	2.9 μs
95th percentile	86.9 μs	89.5 μs	2.6 μs
99th percentile	97.0 μs	102.4 μs	5.4 μs
Allocated memory per request	46.6 KB	48.6 KB	2.0 KB

Benchmark environment

Intel Xeon E3-1230 v3

Linux (ubuntu) 4.4.0-31

Java 1.8.0_101-b13

For comparison, here is the same test run with a leading commercial Java APM:

	Baseline	with a leading commercial Java APM	Overhead
Response times
Average	80.0 μs	133.6 μs	53.6 μs
95th percentile	86.9 μs	143.9 μs	57.0 μs
99th percentile	97.0 μs	157.2 μs	60.2 μs
Allocated memory per request	46.6 KB	81.2 KB	34.6 KB