How does Vim's autoread work?

Question

:h autoread says:

When a file has been detected to have been changed outside of Vim and it has not been changed inside of Vim, automatically

Answer 1

A bit late to the party, but vim nowadays has timers, and you can do:

if ! exists("g:CheckUpdateStarted")
    let g:CheckUpdateStarted=1
    call timer_start(1,'CheckUpdate')
endif
function! CheckUpdate(timer)
    silent! checktime
    call timer_start(1000,'CheckUpdate')
endfunction