Question

I have been researching this for a while but got no convinced answer.

From mysql tutorial, the default connections number is less than two hundred, and it says max_connection_num can be set to 2000 in Linux box as long as you have enough resource. I think this number is far from enough in real world deployment as there might be millions people visit your website at the same time.

There are couple of articles talking about how to optimize to reduce time cost by each query. But none of them tells me how this issue is root caused. I think there must be some mechanism like queue to prevent massive connections from happening simultaneously. otherwise you will finally get “too connection” exception.

anyone has some expertise in this area? thank you.

Answer 1

There are several options.

1. Connection pooling
2. As you mentionned: queuing. If too many clients connect at the same time, then the application layer should handle this exception, put the request to sleep for a short period of time and try again. Requests lasting more than a couple of seconds should usually be banned in such a high traffic environment.
3. Load balancing through replication and/or clustering