If you have access to a Mac or Linux server, chances are you may already have a really simple http load generating tool installed called Apache Bench, or ab. If you are on windows and have Apache installed, you may also have ab.exe in your apache/bin folder.
Suppose we want to see how fast Yahoo can handle 100 requests, with a maximum of 10 requests running concurrently:
ab -n 100 -c 10 http://www.yahoo.com/
It will then generate output as follows:
Concurrency Level: 10 Time taken for tests: 1.889 seconds Complete requests: 100 Failed requests: 0 Write errors: 0 Total transferred: 1003100 bytes HTML transferred: 949000 bytes Requests per second: 52.94 [#/sec] (mean) Time per request: 188.883 [ms] (mean) Time per request: 18.888 [ms] (mean, across all concurrent requests) Transfer rate: 518.62 [Kbytes/sec] received Connection Times (ms) min mean[+/-sd] median max Connect: 57 59 1.7 59 64 Processing: 117 126 7.5 124 162 Waiting: 57 62 7.0 60 98 Total: 175 186 8.0 184 224 Percentage of the requests served within a certain time (ms) 50% 184 66% 186 75% 187 80% 188 90% 192 95% 203 98% 216 99% 224 100% 224 (longest request)
As you can see this is very useful information, it returned requests at a rate of 52.94 requests per second, the fastest request was 175ms, the slowest 224ms
So the next time you are tempted to whip out
GetTickCount to do some benchmarking on a piece of code, give
ab a try, it’s easy to use, and will yield much more realistic results.
ab supports concurrency, this has two big advantages over
cfloop. The main one is that it allows you to test how your code runs concurrently, this can help you identify any possible race conditions, or locking issues. Concurrent requests are also a more natural simulation of load than loops.
Suppose you wanted to test multiple url’s concurrently as well? You can do this by creating a shell script, with multiple
ab calls. At the end of each line place an
& this makes the command run in the background, and lets the next command start execution. You will also want to redirect the output to a file for each url using
> filename For example:
#!/bin/sh ab -n 100 -c 10 http://127.0.0.1:8300/test.cfm > test1.txt & ab -n 100 -c 10 http://127.0.0.1:8300/scribble.cfm > test2.txt &
The usage info from the
ab version installed on my Mac (v2.3) is listed below. As you can see there are many useful options for outputting results, and sending additional data in the request.
Usage: ab [options] [http[s]://]hostname[:port]/path Options are: -n requests Number of requests to perform -c concurrency Number of multiple requests to make -t timelimit Seconds to max. wait for responses -b windowsize Size of TCP send/receive buffer, in bytes -p postfile File containing data to POST. Remember also to set -T -T content-type Content-type header for POSTing, eg. 'application/x-www-form-urlencoded' Default is 'text/plain' -v verbosity How much troubleshooting info to print -w Print out results in HTML tables -i Use HEAD instead of GET -x attributes String to insert as table attributes -y attributes String to insert as tr attributes -z attributes String to insert as td or th attributes -C attribute Add cookie, eg. 'Apache=1234. (repeatable) -H attribute Add Arbitrary header line, eg. 'Accept-Encoding: gzip' Inserted after all normal header lines. (repeatable) -A attribute Add Basic WWW Authentication, the attributes are a colon separated username and password. -P attribute Add Basic Proxy Authentication, the attributes are a colon separated username and password. -X proxy:port Proxyserver and port number to use -V Print version number and exit -k Use HTTP KeepAlive feature -d Do not show percentiles served table. -S Do not show confidence estimators and warnings. -g filename Output collected data to gnuplot format file. -e filename Output CSV file with percentages served -r Don't exit on socket receive errors. -h Display usage information (this message) -Z ciphersuite Specify SSL/TLS cipher suite (See openssl ciphers) -f protocol Specify SSL/TLS protocol (SSL2, SSL3, TLS1, or ALL)