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Today I realized that the VPS I’m renting for $20/mo is not as good as it seemed at first. Ever thought about high loads? Okay, this may sound like some DDoS hacking tools, but no! 100 requests with 10 simultaneous made my virtual private server think for ~ 1,5 minutes. Jeez!
It took me quite some time to find good software for running some load tests on my webserver, linux has some good utilities (linux.com/feature/143896), but I suggest you start from ApacheBench which is a command line utility bundled with the Apache distribution. It’s cross-platform, therefore you can use it on Windows (I did). Anyways, here’s how you launch a test:
ab -n 100 -c 10 http://www.microsoft.com/
Why did I pick Microsoft? Well, if I get like 10,000 views tomorrow and everybody tries that command, that’d be a DDoS attack on Microsoft servers and I think they’re good enough to handle it. My server would just explode :)
Anyways, take a look at what the results may be like:
Benchmarking www.kovshenin.com (be patient).....done Server Software: Apache/2.2.8 Server Hostname: www.kovshenin.com Server Port: 80 Document Path: / Document Length: 84 bytes Concurrency Level: 10 Time taken for tests: 90.984 seconds Complete requests: 100 Failed requests: 1 (Connect: 0, Receive: 0, Length: 1, Exceptions: 0) Write errors: 0 Non-2xx responses: 100 Total transferred: 36564 bytes HTML transferred: 8674 bytes Requests per second: 1.10 [#/sec] (mean) Time per request: 9098.438 [ms] (mean) Time per request: 909.844 [ms] (mean, across all concurrent requests) Transfer rate: 0.39 [Kbytes/sec] received Connection Times (ms) min mean[+/-sd] median max Connect: 0 15 3.4 16 16 Processing: 2203 8866 8879.2 6188 48797 Waiting: 1969 8532 8664.9 5891 48750 Total: 2219 8880 8879.6 6203 48813 Percentage of the requests served within a certain time (ms) 50% 6203 66% 7281 75% 8141 80% 8313 90% 17078 95% 32266 98% 43813 99% 48813 100% 48813 (longest request)
Ah.. And a failed request there, how sad… You might also want to check out your load on the server while benchmarking. Use the ‘top’ command, it should produce similar output:
Yup, although the super cache plugin is working, wordpress consumes a lot of memory… I also ran this with a 500/100 requests, that made my server go down for like 6 minutes, I had over 200 failed requests and my blog kept saying database connection error until the test had finished. Free memory dropped down to 0! Scary? For more information about how ab works, read Apache HTTP server benchmarking tool documentation at apache.org.