AB(1) ab AB(1)
ab - Apache HTTP server benchmarking tool
ab [ -A auth-username:password ] [ -b windowsize ] [ -B local-address ] [ -c concurrency ]
[ -C cookie-name=value ] [ -d ] [ -e csv-file ] [ -f protocol ] [ -g gnuplot-file ] [ -h ]
[ -H custom-header ] [ -i ] [ -k ] [ -n requests ] [ -p POST-file ] [ -P proxy-auth-user-
name:password ] [ -q ] [ -r ] [ -s timeout ] [ -S ] [ -t timelimit ] [ -T content-type ] [
-u PUT-file ] [ -v verbosity] [ -V ] [ -w ] [ -x <table>-attributes ] [ -X proxy[:port] ]
[ -y <tr>-attributes ] [ -z <td>-attributes ] [ -Z ciphersuite ] [http[s]://]host-
ab is a tool for benchmarking your Apache Hypertext Transfer Protocol (HTTP) server. It is
designed to give you an impression of how your current Apache installation performs. This
especially shows you how many requests per second your Apache installation is capable of
Supply BASIC Authentication credentials to the server. The username and password
are separated by a single : and sent on the wire base64 encoded. The string is sent
regardless of whether the server needs it (i.e., has sent an 401 authentication
Size of TCP send/receive buffer, in bytes.
Address to bind to when making outgoing connections.
Number of multiple requests to perform at a time. Default is one request at a time.
Add a Cookie: line to the request. The argument is typically in the form of a
name=value pair. This field is repeatable.
-d Do not display the "percentage served within XX [ms] table". (legacy support).
Write a Comma separated value (CSV) file which contains for each percentage (from
1% to 100%) the time (in milliseconds) it took to serve that percentage of the
requests. This is usually more useful than the 'gnuplot' file; as the results are
Specify SSL/TLS protocol (SSL2, SSL3, TLS1, or ALL).
Write all measured values out as a 'gnuplot' or TSV (Tab separate values) file.
This file can easily be imported into packages like Gnuplot, IDL, Mathematica, Igor
or even Excel. The labels are on the first line of the file.
-h Display usage information.
Append extra headers to the request. The argument is typically in the form of a
valid header line, containing a colon-separated field-value pair (i.e., "Accept-
-i Do HEAD requests instead of GET.
-k Enable the HTTP KeepAlive feature, i.e., perform multiple requests within one HTTP
session. Default is no KeepAlive.
Number of requests to perform for the benchmarking session. The default is to just
perform a single request which usually leads to non-representative benchmarking
File containing data to POST. Remember to also set -T.
Supply BASIC Authentication credentials to a proxy en-route. The username and pass-
word are separated by a single : and sent on the wire base64 encoded. The string is
sent regardless of whether the proxy needs it (i.e., has sent an 407 proxy authen-
-q When processing more than 150 requests, ab outputs a progress count on stderr every
10% or 100 requests or so. The -q flag will suppress these messages.
-r Don't exit on socket receive errors.
Maximum number of seconds to wait before the socket times out. Default is 30 sec-
-S Do not display the median and standard deviation values, nor display the warn-
ing/error messages when the average and median are more than one or two times the
standard deviation apart. And default to the min/avg/max values. (legacy support).
Maximum number of seconds to spend for benchmarking. This implies a -n 50000 inter-
nally. Use this to benchmark the server within a fixed total amount of time. Per
default there is no timelimit.
Content-type header to use for POST/PUT data, eg. application/x-www-form-urlen-
coded. Default is text/plain.
File containing data to PUT. Remember to also set -T.
Set verbosity level - 4 and above prints information on headers, 3 and above prints
response codes (404, 200, etc.), 2 and above prints warnings and info.
-V Display version number and exit.
-w Print out results in HTML tables. Default table is two columns wide, with a white
String to use as attributes for <table>. Attributes are inserted <table here >.
Use a proxy server for the requests.
String to use as attributes for <tr>.
String to use as attributes for <td>.
Specify SSL/TLS cipher suite (See openssl ciphers)
The following list describes the values returned by ab:
The value, if any, returned in the server HTTP header of the first successful
response. This includes all characters in the header from beginning to the point a
character with decimal value of 32 (most notably: a space or CR/LF) is detected.
The DNS or IP address given on the command line
The port to which ab is connecting. If no port is given on the command line, this
will default to 80 for http and 443 for https.
The protocol parameters negotiated between the client and server. This will only be
printed if SSL is used.
The request URI parsed from the command line string.
This is the size in bytes of the first successfully returned document. If the docu-
ment length changes during testing, the response is considered an error.
The number of concurrent clients used during the test
Time taken for tests
This is the time taken from the moment the first socket connection is created to
the moment the last response is received
The number of successful responses received
The number of requests that were considered a failure. If the number is greater
than zero, another line will be printed showing the number of requests that failed
due to connecting, reading, incorrect content length, or exceptions.
The number of errors that failed during write (broken pipe).
The number of responses that were not in the 200 series of response codes. If all
responses were 200, this field is not printed.
The number of connections that resulted in Keep-Alive requests
Total body sent
If configured to send data as part of the test, this is the total number of bytes
sent during the tests. This field is omitted if the test did not include a body to
The total number of bytes received from the server. This number is essentially the
number of bytes sent over the wire.
The total number of document bytes received from the server. This number excludes
bytes received in HTTP headers
Requests per second
This is the number of requests per second. This value is the result of dividing the
number of requests by the total time taken
Time per request
The average time spent per request. The first value is calculated with the formula
concurrency * timetaken * 1000 / done while the second value is calculated with the
formula timetaken * 1000 / done
The rate of transfer as calculated by the formula totalread / 1024 / timetaken
There are various statically declared buffers of fixed length. Combined with the lazy
parsing of the command line arguments, the response headers from the server and other
external inputs, this might bite you.
It does not implement HTTP/1.x fully; only accepts some 'expected' forms of responses. The
rather heavy use of strstr(3) shows up top in profile, which might indicate a performance
problem; i.e., you would measure the ab performance rather than the server's.
Apache HTTP Server 2013-01-09 AB(1)