Question

I have a PHP CURL request to an HTTPS site which takes a JSON and request and returns a JSON response. Usually it should not take more than 1 second. But, I have seen that the CURL response time is variable. Sometimes, it takes 4 seconds to respond and sometimes 1.2 seconds. Why is this so and How can I make it faster and process the whole request in less than a second?

Following is the curl response times for the same request in 3 different times..

Array
(
    [url] => https://xx.xx.xxx.xx/site/y
    [content_type] => application/json
    [http_code] => 200
    [header_size] => 198
    [request_size] => 358
    [filetime] => -1
    [ssl_verify_result] => 20
    [redirect_count] => 0
    [total_time] => 4.213941
    [namelookup_time] => 2.1E-5
    [connect_time] => 0.015284
    [pretransfer_time] => 0.722955
    [size_upload] => 222
    [size_download] => 553
    [speed_download] => 131
    [speed_upload] => 52
    [download_content_length] => 0
    [upload_content_length] => 0
    [starttransfer_time] => 4.015112
    [redirect_time] => 0
)


Array
(
    [url] => https://xx.xx.xxx.xx/site/y
    [content_type] => application/json
    [http_code] => 200
    [header_size] => 198
    [request_size] => 358
    [filetime] => -1
    [ssl_verify_result] => 20
    [redirect_count] => 0
    [total_time] => 1.27581
    [namelookup_time] => 8.3E-5
    [connect_time] => 0.016223
    [pretransfer_time] => 0.104996
    [size_upload] => 222
    [size_download] => 553
    [speed_download] => 433
    [speed_upload] => 174
    [download_content_length] => 0
    [upload_content_length] => 0
    [starttransfer_time] => 1.273922
    [redirect_time] => 0
)

Array
(
    [url] => https://xx.xx.xxx.xx/site/y
    [content_type] => application/json
    [http_code] => 200
    [header_size] => 198
    [request_size] => 358
    [filetime] => -1
    [ssl_verify_result] => 20
    [redirect_count] => 0
    [total_time] => 1.294147
    [namelookup_time] => 7.0E-5
    [connect_time] => 0.025723
    [pretransfer_time] => 0.123456
    [size_upload] => 222
    [size_download] => 553
    [speed_download] => 427
    [speed_upload] => 171
    [download_content_length] => 0
    [upload_content_length] => 0
    [starttransfer_time] => 1.292577
    [redirect_time] => 0
)

Answer 1

What else is the site doing ? If it has a fixed number of threads (say), and each is busy, then your request will have to wait for a thread to service it. If no threads are busy, then it’ll be serviced immediately.

Of course the simplest scenario is given that the server CPU has finite resources and servicing an indeterminate number of requests, there are no service guaranteees.