问题
When I am increasing concurrency -c in ab (apache bench) then I am getting different response time.
-c 99%
3 2ms
5 4ms
8 6ms
If I increase -c further then response time will increase as well.My code is extremely simple, No thread starvation, no blocking, etc. Then why the response time is getting increased?
I think that ab -c 8 means 8 simultaneous request would be made to http://localhost:8070/benchmark. So is it possible that requests are getting pooled at tomcat? If it is so then how can I make tomcat handle more concurrent users with less response time (4ms at 99%)?
@RestController
public class PerformanceController {
@RequestMapping(value="/benchmark",method=RequestMethod.GET)
public String getRetargetingData(){
return "Just plain call";
}
}
ritesh@ritesh:~$ ab -n 10000 -c 3 'http://localhost:8070/benchmark'
Server Software: Apache-Coyote/1.1
Server Hostname: localhost
Server Port: 8070
Document Path: /benchmark
Document Length: 15 bytes
Concurrency Level: 3
Time taken for tests: 2.602 seconds
Complete requests: 10000
Failed requests: 0
Total transferred: 4050000 bytes
HTML transferred: 150000 bytes
Requests per second: 3843.57 [#/sec] (mean)
Time per request: 0.781 [ms] (mean)
Time per request: 0.260 [ms] (mean, across all concurrent requests)
Transfer rate: 1520.16 [Kbytes/sec] received
Connection Times (ms)
min mean[+/-sd] median max
Connect: 0 0 0.0 0 0
Processing: 0 1 0.5 1 23
Waiting: 0 1 0.4 1 23
Total: 0 1 0.5 1 24
Percentage of the requests served within a certain time (ms)
50% 1
66% 1
75% 1
80% 1
90% 1
95% 1
98% 2
99% 2
100% 24 (longest request)
ritesh@ritesh:~$ ab -n 10000 -c 6 'http://localhost:8070/benchmark'
Server Software: Apache-Coyote/1.1
Server Hostname: localhost
Server Port: 8070
Document Path: /benchmark
Document Length: 15 bytes
Concurrency Level: 6
Time taken for tests: 1.814 seconds
Complete requests: 10000
Failed requests: 0
Total transferred: 4050000 bytes
HTML transferred: 150000 bytes
Requests per second: 5514.16 [#/sec] (mean)
Time per request: 1.088 [ms] (mean)
Time per request: 0.181 [ms] (mean, across all concurrent requests)
Transfer rate: 2180.89 [Kbytes/sec] received
Connection Times (ms)
min mean[+/-sd] median max
Connect: 0 0 0.0 0 1
Processing: 0 1 0.9 1 22
Waiting: 0 1 0.8 1 22
Total: 0 1 0.9 1 22
Percentage of the requests served within a certain time (ms)
50% 1
66% 1
75% 1
80% 1
90% 2
95% 2
98% 3
99% 4
100% 22 (longest request)
ritesh@ritesh:~$ ab -n 10000 -c 8 'http://localhost:8070/benchmark'
Server Software: Apache-Coyote/1.1
Server Hostname: localhost
Server Port: 8070
Document Path: /benchmark
Document Length: 15 bytes
Concurrency Level: 8
Time taken for tests: 1.889 seconds
Complete requests: 10000
Failed requests: 0
Total transferred: 4050000 bytes
HTML transferred: 150000 bytes
Requests per second: 5293.55 [#/sec] (mean)
Time per request: 1.511 [ms] (mean)
Time per request: 0.189 [ms] (mean, across all concurrent requests)
Transfer rate: 2093.64 [Kbytes/sec] received
Connection Times (ms)
min mean[+/-sd] median max
Connect: 0 0 0.0 0 2
Processing: 0 1 1.8 1 50
Waiting: 0 1 1.8 1 50
Total: 0 1 1.8 1 50
Percentage of the requests served within a certain time (ms)
50% 1
66% 1
75% 2
80% 2
90% 2
95% 3
98% 5
99% 6
100% 50 (longest request)
ritesh@ritesh:~$ ab -n 10000 -c 500 'http://localhost:8070/benchmark'
Server Software: Apache-Coyote/1.1
Server Hostname: localhost
Server Port: 8070
Document Path: /benchmark
Document Length: 15 bytes
Concurrency Level: 500
Time taken for tests: 1.830 seconds
Complete requests: 10000
Failed requests: 0
Total transferred: 4050000 bytes
HTML transferred: 150000 bytes
Requests per second: 5464.11 [#/sec] (mean)
Time per request: 91.506 [ms] (mean)
Time per request: 0.183 [ms] (mean, across all concurrent requests)
Transfer rate: 2161.10 [Kbytes/sec] received
Connection Times (ms)
min mean[+/-sd] median max
Connect: 0 25 154.8 0 1001
Processing: 1 23 45.7 12 818
Waiting: 1 23 45.6 12 818
Total: 2 48 188.5 12 1818
Percentage of the requests served within a certain time (ms)
50% 12
66% 17
75% 22
80% 26
90% 45
95% 66
98% 1021
99% 1220
100% 1818 (longest request)
来源：https://stackoverflow.com/questions/26030851/tomcat-response-time-is-increasing-as-concurrency-is-increased-in-apache-bench