当我在ab（apache bench）中增加并发性-c时，我的响应时间会有所不同。
-c 99%
3 2ms
5 4ms
8 6ms
如果我进一步增加-c，那么响应时间也会增加。我的代码非常简单，没有线程饥饿，没有阻塞等等。那么为什么响应时间会增加？
我认为ab -c 8表示同时向http://localhost:8070/benchmark发出请求。那么是否有可能将请求汇集到tomcat？如果是这样的话，那么如何让tomcat处理更多并发用户的响应时间更短（4ms为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)