What is concurrent request (-c) in Apache Benchmark?

Question

What is concurrent request (-c) in apache benchmark?

I think it is number of simultaneous request(Process) created in single point of time?

Can anybody explain if I am wrong? Can you give some example how concurrent request will work? How can I test this like Boundary Value Analysis(BVA) testing

It's number of users trying to access the same resource in a given period of time (second). — Michael J.V.
So it uses same thread (or different tread?) for all the users ? (Process thread). Will it create any bottleneck if concurrency is more in high traffic site (?) — Sahal
Check out this answer. It includes a very lucid description of concurrency. — Suganya

Rakesh Sankar Rakesh Sankar · Accepted Answer · 2011-07-27T06:55:11

You are correct.

In simple words, ab -n 1000 -c 5 http://www.example.com/

where,

-n 1000: ab will send 1000 number of requests to example.com server in order to perform for the benchmarking session

-c 5 : 5 is concurrency number i.e. ab will send 5 number of multiple requests to perform at a same time to example.com server

Came across the following SO question where one of the answer says ab is not a perfect benchmark tool, since, you have CSS/JS/Images factors to consider when it comes to benchmark - Can someone please explain what these ApacheBench results mean?

What is concurrent request (-c) in Apache Benchmark?

2 Answers