Understanding of the number of concurrent users

What is the number of concurrent users, many people will take this indicator to measure the good and bad of a network system, just beginning to contact LoadRunner, once thought that the virtual user is called the number of concurrent users, but after a series of tests, found that this view is not how all is correct.
First of all, to divide into two test cases, the first is to run a Web page of actual business testing, such as the educational system, observing its landing transactions, query transactions, and the second, test run a single static page, or dynamic page, the performance of the server.
First, you can design a centralized point, let the virtual user log in at the same time, to observe the response to the transaction situation, then this observation point, it can be said that the same time, the number of concurrent logins is your virtual user number.
Second, the test of a single page, the assumption is a static page, this static page, does not exist get a picture page, simply request an HTML page, this time, the number of virtual users is not quite correct, when you will find that when you set up 100 virtual users or 1000 virtual users, The performance effect of the network system is close, does that mean that our number of concurrent users has reached 1000? The answer is no, because your system, which has already been pressurized to 1000 users, has reached the bottleneck, especially in terms of your pressurized throughput. Observing your system throughput per second is not to stay around 10M, or about 100M, if it is stuck in such a few numbers, indicating that your system in your pressure to 1000 virtual users, throughput has reached the bottleneck, no matter how you pressure, are not virtual users of the problem, then for this situation, How to determine how many concurrent numbers, I personally think, is the number of hits per second, if your test page is simply a static page, then your number of hits per second is your maximum number of concurrent, let us re-understand the concept of concurrency, concurrency, can be understood as the number of concurrent users, can also be understood as the number of concurrent connections, Concurrent users more inclined to 7-layer network understanding, he is a kind of business concurrency number, such as analog user simultaneous login, and the number of concurrent connections, is biased to 4 layer network, is a TCP connection, need to know how many TCP connections this server can receive at the same time.
When we tested the specific business, we tested the number of concurrent transactions for the virtual user
When we test a single static page, we are testing the number of concurrent TCP connections, which I think is basically equal to the amount of hits per second.

Understanding the number of concurrent users