I am just trying to gather some information on server capacity and ran these apache ab test.
I tested with 1, 10, 100, 1000 concurrency over 1 minute. The result below is for 1000 concurrent users
I am using this benchmark script – https://github.com/odan/benchmark-php/blob/master/benchmark.php
Only thing I have changed is to replace MySQL Benchmark(1 million, Encode(…)) query with another simpler Benchmark(1 million, 1+1)
The script takes approx 0.52 seconds to complete so in one minute I would expect near about 115 completed requests in ideal conditions.
Result of ab -t 60 -n 5000 -kc 1000 mydomain-name/benchmark.php
Benchmarking mydomain-name (be patient)
Finished 111 requests
Server Software: Apache/2.4.18
Document Path: /benchmark.php
Document Length: 4210 bytes
Concurrency Level: 1000
Time taken for tests: 60.383 seconds
Complete requests: 111
Failed requests: 0
Keep-Alive requests: 0
Total transferred: 486180 bytes
HTML transferred: 467310 bytes
Requests per second: 1.84 [#/sec] (mean)
Time per request: 543987.550 [ms] (mean)
Time per request: 543.988 [ms] (mean, across all concurrent requests)
Transfer rate: 7.86 [Kbytes/sec] received
Connection Times (ms)
min mean[+/-sd] median max
Connect: 57 136 42.2 140 199
Processing: 2362 30681 16963.4 31249 60180
Waiting: 2362 30680 16963.4 31248 60180
Total: 2425 30817 17005.2 31389 60378
Percentage of the requests served within a certain time (ms)
50% 31306
66% 39785
75% 45021
80% 47629
90% 54320
95% 57756
98% 58191
99% 59632
100% 60378 (longest request)
So it shows, with 1000 concurrency level, it completed 111 requests. My questions are:
1) It shows two Time per requests values. I know that script takes about 520 milliseconds to run when I check in the browser. So is the second value of 543.988 [ms] (mean, across all concurrent requests) the actual time per request when the test was running? First Time per request value of 543987.550 seems to be just: 543.988 x 1000 (concurrent users)? so does that mean it took approx 54 seconds to run the tests (where as "Time take for tests" says 60.383 seconds?)
All I am trying to do is to learn at what point it starts affecting server performance. Looking at above at 1000 concurrency level, it is still able to serve 1.84 requests per second at mean time per request of 543 milliseconds – which is what it to expect when there is no load?
If you are interested here is data for 10 and 100 concurrency level.
ab -t 60 -k -n 500 -c 10 mydomain-name/benchmark.php
Benchmarking mydomain-name (be patient)
Completed 100 requests
Finished 111 requests
Document Path: /benchmark.php
Document Length: 4210 bytes
Concurrency Level: 10
Time taken for tests: 60.038 seconds
Complete requests: 111
Failed requests: 0
Keep-Alive requests: 0
Total transferred: 486180 bytes
HTML transferred: 467310 bytes
Requests per second: 1.85 [#/sec] (mean)
Time per request: 5408.824 [ms] (mean)
Time per request: 540.882 [ms] (mean, across all concurrent requests)
Transfer rate: 7.91 [Kbytes/sec] received
Connection Times (ms)
min mean[+/-sd] median max
Connect: 10 11 1.5 11 20
Processing: 1743 5170 647.3 5251 6893
Waiting: 1743 5169 647.3 5251 6892
Total: 1754 5181 647.5 5262 6906
Percentage of the requests served within a certain time (ms)
50% 5260
66% 5308
75% 5370
80% 5391
90% 5441
95% 5510
98% 5540
99% 5967
100% 6906 (longest request)
I repeated the same test with 100 concurrent users.
ab -t 60 -n 2000 -c 100 -k mydomain-name/benchmark.php
Benchmarking mydomain-name (be patient)
Finished 114 requests
Server Software: Apache/2.4.18
Server Port: 80
Document Path: /benchmark.php
Document Length: 4210 bytes
Concurrency Level: 100
Time taken for tests: 60.683 seconds
Complete requests: 114
Failed requests: 0
Keep-Alive requests: 0
Total transferred: 499320 bytes
HTML transferred: 479940 bytes
Requests per second: 1.88 [#/sec] (mean)
Time per request: 53230.746 [ms] (mean)
Time per request: 532.307 [ms] (mean, across all concurrent requests)
Transfer rate: 8.04 [Kbytes/sec] received
Connection Times (ms)
min mean[+/-sd] median max
Connect: 10 21 4.0 21 28
Processing: 1932 30540 16362.9 30710 54039
Waiting: 1931 30539 16362.9 30710 54038
Total: 1953 30561 16362.6 30732 54066
Percentage of the requests served within a certain time (ms)
50% 30732
66% 41063
75% 46327
80% 48960
90% 52212
95% 52273
98% 52288
99% 52840
100% 54066 (longest request)
Best Answer
What you're actually seeing is an application that is "serializing" request processing- meaning, only one request is being processed at a time, regardless of the number of requests that are being issued to it.
Note the consistency of the RPS across concurrency levels- always around 1.8- and note that 1.8 is about 1/service time of a single request (.53 secs).
The application is receiving 1 or 10 or 100 or 1000 requests, is picking one of them, queuing the rest (there are various ways this is done under the hood), processing the one it picked in .53 seconds, returning results, then picking another of the requests that are being queued, processing it, completing, returning results, etc for 60 seconds.
So- that's the "capacity" of this configuration- a little less than 2 requests per second- which is irrespective of incoming concurrent request rate.
Since this is 2018 and not 1993, you probably want to fix that. :) You should be able to do hundreds to- sometimes- thousands of requests/sec with PHP on a single reasonably sized and configured node.
Why exactly are requests being serialized? It's either something in the benchmark script- grabbing a lock or doing some other serialized action- or something in server configuration- number of web server workers, etc. If you can't figure it out, maybe create another question with the details and someone can probably help.