Wait for grandchild to be ready when daemonizing
When lighttpd does the sys-v-init daemonizing (without the -D switch) the parent process will immeadeatly terminate after the first fork (see function daemonize in server.c).
This can cause problems, when right after the start of lighttpd the presence/correctness of the pid is checked or the pid of the daemon process is tried to grabbed by `pidof lighttpd` or similar. The second problem becomes a problem because of the double forking. If the timing "fits" you get only the pid of the child but not the grandchild (or both).
Following this guide (http://www.freedesktop.org/software/systemd/man/daemon.html) it is a more clean way to terminated the parent process only if the child is fully up and running (after every initialization is ok and the pid file is written).
I wrote a patch that fixes this behaviour. As suggested in the reference above it uses a pipe as communication channel between parent and grandchild.
Updated by gstrauss over 5 years ago
Additionally, when there are multiple workers, the first worker (greatgrandchild) calls write(), and then the grandparent calls read() and close(). Once you fix the
pipefd leak in the grandchild (which I mentioned in the comment above), then subsequent workers might fail to write() with EPIPE after the grandparent calls close() on the read-end of the pipe (
Please consider moving the write() to a location prior to spawning of workers, but after the daemonized grandchild is up and running, and after the grandchild has written its pid to the pidfile. Such a location would be a reasonable place for the grandparent to exit while still ensuring that
pidof would return the proper pid of the running grandchild.
Updated by pasdVn over 5 years ago
Thanks for your feedback. I moved the grandchild's write() directly before the fork-loop where the workers are created. I think this is the best place under this circumstances.
Also available in: Atom