Load Test

Generate load with URLs from access log.

Running a load test is fairly simple: just fire many requests to the server and gradually increase the number. However, the traffic this generates is often different from the patterns actually observed in production. Either a handful URLs is queried again and again or the site is spidered and every URL is accessed an equal number of times. In reality, a site has some popular URLs and some less popular URLs. Both of them are potential sources of latency. By generating load based on an access log, the distribution across URLs is more production-like. Also, typical 404s are tested and some funny query strings may be introduced as they would be in the real world.

Please note:

• Time stamps are ignored The purpose of using an access-log is to get closer to production-like patterns, not replicating the exact traffic.
• Only GET requests (no POST/PUT/HEAD/DELETE/etc)
• Status codes in the access log are ignored so 200, 301, 302, 404, 500 etc are still getting called
• Any query strings are still in the URL

Running:

Usage of loadtest:
  -b string
    	base URL as prefix in front of paths in access logs
  -c int
    	number of concurrent requests (default 2)
  -f string
    	comma-separated list of URLs to filter (default "a,b,c")
  -k	keep cookies across requests
  -l string
    	file name of access log file to interpret
  -r int
    	report interval in seconds (default 1)
  -rp
    	repeat after done reading log file
  -s	suppress errors
  -v	verbose output

e.g.:

./loadtest -l=myaccesslogfile.log -f=http,//,/undesirable,/my-api -b=https://www.mydomain.com -r=5 -c=2 -k

Production experience

From experience, use concurrency 384 as a maximum concurrency per process. Spin up multiple instances of this load test on a single machine to get beyond this. A total number of 4 load tests ran well on a single machine (m4.2xlarge)

Building

Make sure you have a recent version of Go installed.

GOOS=linux GOARCH=amd64 go get github.com/adriaandejonge/loadtest
GOOS=windows GOARCH=amd64 go get github.com/adriaandejonge/loadtest
GOOS=darwin GOARCH=amd64 go get github.com/adriaandejonge/loadtest