http：keep-alive保持php资源打开还是释放所有资源？

Question

I am using http keep-alive on a apache server,
Lets say I ask it to keep the connections open upto 2 minutes...
Now, if the connection is created and idle for a minute, will the resources held by php,
like mysql connections, file handles, etc., will be freed or will they survive too ?

Answer 1

Confirmed. Keep-Alive is a mechanism to prevent costly TCP connection negotiation. Your PHP process/thread starts as normal and needs to allocate all resources as usual.

Regarding a high load situation, it might be wise to even keep the keep-alive period not too high: All connection requests compete for free connection slots of your server. If all slots are in-use by keep-alive connections, other users might not connect.

But, as usual, the optimal amount of slots and good keep-alive period depends on your specific load situation.