wrk - a HTTP benchmarking tool wrk is a modern HTTP benchmarking tool capable of generating significant load when run on a single multi-core CPU. It combines a multithreaded design with scalable event notification systems such as epoll and kqueue. An optional LuaJIT script can perform HTTP request generation, response processing, and custom reporting. Basic Usage wrk -t12 -c400 -d30s http://127.0.0.1:8080/index.html This runs a benchmark for 30 seconds, using 12 threads, and keeping 400 HTTP connections open. Output: Running 30s test @ http://127.0.0.1:8080/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% 22464657 requests in 30.00s, 17.76GB read Requests/sec: 748868.53 Transfer/sec: 606.33MB Scripting wrk's public Lua API is: init = function(args) request = function() response = function(status, headers, body) done = function(summary, latency, requests) wrk = { scheme = "http", host = "localhost", port = nil, method = "GET", path = "/", headers = {}, body = nil } function wrk.format(method, path, headers, body) wrk.format returns a HTTP request string containing the passed parameters merged with values from the wrk table. global init -- function called when the thread is initialized global request -- function returning the HTTP message for each request global response -- optional function called with HTTP response data global done -- optional function called with results of run The init() function receives any extra command line arguments for the script. Script arguments must be separated from wrk arguments with "--" and scripts that override init() but not request() must call wrk.init() The done() function receives a table containing result data, and two statistics objects representing the sampled per-request latency and per-thread request rate. Duration and latency are microsecond values and rate is measured in requests per second. latency.min -- minimum value seen latency.max -- maximum value seen latency.mean -- average value seen latency.stdev -- standard deviation latency:percentile(99.0) -- 99th percentile value latency[i] -- raw sample value summary = { duration = N, -- run duration in microseconds requests = N, -- total completed requests bytes = N, -- total bytes received errors = { connect = N, -- total socket connection errors read = N, -- total socket read errors write = N, -- total socket write errors status = N, -- total HTTP status codes > 399 timeout = N -- total request timeouts } } Benchmarking Tips The machine running wrk must have a sufficient number of ephemeral ports available and closed sockets should be recycled quickly. To handle the initial connection burst the server's listen(2) backlog should be greater than the number of concurrent connections being tested. A user script that only changes the HTTP method, path, adds headers or a body, will have no performance impact. If multiple HTTP requests are necessary they should be pre-generated and returned via a quick lookup in the request() call. Per-request actions, particularly building a new HTTP request, and use of response() will necessarily reduce the amount of load that can be generated. Acknowledgements wrk contains code from a number of open source projects including the 'ae' event loop from redis, the nginx/joyent/node.js 'http-parser', Mike Pall's LuaJIT, and the Tiny Mersenne Twister PRNG. Please consult the NOTICE file for licensing details.