> one of the cool things about unix is (and perhaps windows can do this in the right modes, idk), the running copy of a program is a link to the code on the disk (a link is a reference to the file, without the file name). You can delete a running program from the disk and replace it with a new program, but the running copy will continue and not be aware that you've done that. You don't need to wait till the program finishes anything.
An even cooler thing is the running code is just mmaped into memory. One of the nifty things about mmaped files is if you change the backing file, you change it everywhere.
Not my recommended way to hot load code, but it might work in a pinch.
unlink, replace, start a new one, have the old one stop listening does work for many things. Some OSes have/had issues with dropping a couple pending connections sometimes; or you have to learn the secret handshake to do it right. A bigger problem is if your daemon is sized to fit your memory, you might not be able to run a draining and a filling daemon at once.
It also doesn't really solve the issue of changing code for existing connections, it's a point in time migration. Easier to reason about, for sure, but not always as effective.
An even cooler thing is the running code is just mmaped into memory. One of the nifty things about mmaped files is if you change the backing file, you change it everywhere.
Not my recommended way to hot load code, but it might work in a pinch.
unlink, replace, start a new one, have the old one stop listening does work for many things. Some OSes have/had issues with dropping a couple pending connections sometimes; or you have to learn the secret handshake to do it right. A bigger problem is if your daemon is sized to fit your memory, you might not be able to run a draining and a filling daemon at once.
It also doesn't really solve the issue of changing code for existing connections, it's a point in time migration. Easier to reason about, for sure, but not always as effective.