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0f8016c May 8, 2015
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Overview
wrk supports executing a LuaJIT script during three distinct phases: setup,
running, and done. Each wrk thread has an independent scripting environment
and the setup & done phases execute in a separate environment which does
not participate in the running phase.
The public Lua API consists of a global table and a number of global
functions:
wrk = {
scheme = "http",
host = "localhost",
port = nil,
method = "GET",
path = "/",
headers = {},
body = nil,
thread = <userdata>,
}
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.
function wrk.lookup(host, service)
wrk.lookup returns a table containing all known addresses for the host
and service pair. This corresponds to the POSIX getaddrinfo() function.
function wrk.connect(addr)
wrk.connect returns true if the address can be connected to, otherwise
it returns false. The address must be one returned from wrk.lookup().
The following globals are optional, and if defined must be functions:
global setup -- called during thread setup
global init -- called when the thread is starting
global delay -- called to get the request delay
global request -- called to generate the HTTP request
global response -- called with HTTP response data
global done -- called with results of run
Setup
function setup(thread)
The setup phase begins after the target IP address has been resolved and all
threads have been initialized but not yet started.
setup() is called once for each thread and receives a userdata object
representing the thread.
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
Only boolean, nil, number, and string values or tables of the same may be
transfered via get()/set() and thread:stop() can only be called while the
thread is running.
Running
function init(args)
function delay()
function request()
function response(status, headers, body)
The running phase begins with a single call to init(), followed by
a call to request() and response() for each request cycle.
The init() function receives any extra command line arguments for the
script which must be separated from wrk arguments with "--".
delay() returns the number of milliseconds to delay sending the next
request.
request() returns a string containing the HTTP request. Building a new
request each time is expensive, when testing a high performance server
one solution is to pre-generate all requests in init() and do a quick
lookup in request().
response() is called with the HTTP response status, headers, and body.
Parsing the headers and body is expensive, so if the response global is
nil after the call to init() wrk will ignore the headers and body.
Done
function done(summary, latency, requests)
The done() function receives a table containing result data, and two
statistics objects representing the 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 value and count
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
}
}