Measures

response time ： The time when the system responds to the request . For example, the system deals with a HTTP Request needs 200ms, This 200ms Is the response time of the system .

The response time of a request is of no value , The factors that affect the time of a single request vary , Only a response time curve over a period of time can help check the problem , If you sort according to the request response time from small to large, you can more intuitively see the proportion of each request time , Sensitive to slow requests , This method becomes TP indicators ; If you sort by timeline , Help to check the problem .

Mean response time AVG： The most commonly used , such as 1 Ten thousand requests , among 9900 Next is 1ms,100 Next is 100ms, The average response time is 1.99ms, Although the average time spent has only increased 0.99ms, however 1% The response time for requests has increased 100 times . Can't reflect the slow request .

TP Quantile index ： In a period of time , Count the time consumed by each call of the method , And sort these times from small to large , And the result is .TP34 Quantile mark No 34 Response time of requests .

The lower the index, the better ：

• TP90 It is the minimum time required to meet 90% of network requests .
• TP99 Is the minimum time required to meet 99% of network requests .
• TP999 It is the minimum time required to meet 999 / 1000 network requests .

Empirical value

From a user experience perspective ,200 Millisecond is considered the first cut-off point , Users don't feel the delay

1 Second is the second cut-off point , Users can feel the delay , But it's acceptable .

therefore , For a healthy, highly concurrent system ,TP99 It should be controlled in 200 Within milliseconds ,TP999 perhaps TP9999 It should be controlled in 1 Within seconds .

Index setting

For highly concurrent systems , Performance targets are set with both throughput and response time in mind

For example, to say ： Every second 1 Ten thousand requests , The average response time is controlled at 50ms following ,TP99(99% Request ) Control in 100ms following .

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