ab测试Failed requests问题

今天测试自己写的nginx模块时，出现下面

 

Server Software: nginx/1.0.4
Server Hostname: 192.168.13.105
Server Port: 8100
Document Path: /notice.txt
Document Length: 15 bytes
Concurrency Level: 10
Time taken for tests: 1.783407 seconds
Complete requests: 10000
Failed requests: 5746
(Connect: 0, Length: 5746, Exceptions: 0)
Write errors: 0
Total transferred: 2034960 bytes
HTML transferred: 154772 bytes
Requests per second: 5607.25 [#/sec] (mean)
Time per request: 1.783 [ms] (mean)
Time per request: 0.178 [ms] (mean, across all concurrent requests)
Transfer rate: 1114.16 [Kbytes/sec] received

但是在ab测试过程中，我手动请求测试url返回正常，而且Requests per second也有5600rps,证明响应很快啊，google了一下，网上有人说是页面内容问题。我把我代码改一下，返回相同的内容后，再测试一下发现：

Failed requests: 0

原来ab测试的错误请求是根据内容来判断的呀

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