Within the interest of cleaning temporary files around the webserver, I am wondering if there's in whatever way to inform when X-Sendfile downloads complete... maybe inside a log somewhere? My understanding presently is the fact that when you pass from the headers it's essentially by itself...
I'm not sure of these way, but when you're running on Linux, i quickly think you are able to securely take away the file even when a download continues to be happening. The file is going to be erased immediately however the inode is going to be stored intact until all references into it have left.
Apache only logs a success when the connection's closed, which most probably could be whenever the download is completed. So monitoring the access log for that specific download url would let you know when it is completed - evaluating the drenched bytes-sent v.s. just how much you would expect to transmit will even let you know when the download was effective or maybe it had been aborted.
If at all possible, you are able to temporary shutdown apache beautifully with
apachectl -k graceful-stop. When stopped, in the end demands are finished, you are able to take away the temporary files and begin apache again.