What is wrk load testing tool

wrk is a modern HTTP benchmarking tool capable of generating significant load when run on a single multi-core CPU.

brew install wrk

wrk -t12 -c400 -d30s --latency http://127.0.0.1:8080/index.html

This runs a benchmark for 30 seconds, using 12 threads, and keeping 400 HTTP connections open.

Running 30s test @ http://localhost:8080/index.html

  12 threads and 400 connections

  Thread Stats   Avg      Stdev     Max   +/- Stdev

    Latency   635.91us    0.89ms  12.92ms   93.69%

    Req/Sec    56.20k     8.07k   62.00k    86.54%

Latency Distribution

  50% 250.00us

  75% 491.00us

  90% 700.00us

  99% 5.80ms  

22464657 requests in 30.00s, 17.76GB read

Requests/sec: 748868.53

Transfer/sec:    606.33MB

You can see the average latency of the request, but most important (with the parameter --latency) the quantile.

it’s also possible with the parameter -s to send lua script because wrk supports executing a LuaJIT script , and that’s fantastic, to be able to script our benchmark tests.

-- init random

math.randomseed(os.time())

-- the request function that will run at each request

request = function() 

   

   -- define the path that will search for q=%v 9%v being a random 

      number between 0 and 1000)

   url_path = "/somepath/search?q=" .. math.random(0,1000)

-- if we want to print the path generated

   --print(url_path)

-- Return the request object with the current URL path

   return wrk.format("GET", url_path)

end

wrk -c1 -t1 -d5s -s ./my-script.lua --latency http://localhost:8000

wrk run in 3 phase :

setup

running

done

Setup

The setup phase begins after the target IP address has been resolved and all threads have been initialized but not yet started.

At this point you can change for each thread being execute the addresses found during the Ip target phase. you are able to manipulate

thread.addr : get or set the thread’s server address

thread:get(name) : get the value of a global in the thread’s env

thread:set(name, value) — set the value of a global in the thread’s env

thread:stop() — stop the thread

setup = function(thread)   

   -- code

end

Running

The most useful one.

Running phase are split in 3 others steps :

init

request

response

function init(args)