when the server listens, it takes a certain amount of time to process a client's connection each time, which is very short (perhaps only 1ms or less), but this time still exists. The meaning of this backlog is that while the first connection request is being processed during this time, other connection requests are waiting in the request queue, and if the queue's maximum number of waits is exceeded, the other requests are ignored or will not be processed. the
value of this backlog is the size of the queue that is affected. However, the backlog value is not directly equal to the number of queues, the actual size of the queue varies depending on the operating system. There may be some of this value, there are 2 * backlog + 1, or other formulas and so on.
Personal Understanding, for reference only!
The meaning of the backlog in the socket listen parameter!
