Hi there.
We've got a small launcher script (~250 loc) for parallel services
start/stop etc. It is used on our embedded systems and our users
containers. And I've done a proof of concept for implanting it to the
FreeBSD's standard /etc/rc for execution starting scripts in parallel.
It gave me a boot time reduction of rc part from 27 to 7 seconds, mostly
on eliminating jams for network or other long-latency resources waiting.
The launcher is written in pure POSIX shell and uses FIFOs (named pipes)
as a mutexes for synchronization. So it is embedded into /etc/rc and
/etc/rc.d preserving rc.subr preloading. As a primary requirement, it
guarantees topological order (strict partial order) defined by
dependencies. It requires only POSIX shell, FreeBSD or Linux kernel,
mkfifo and a writeable file system. Due to last requirement, it can be
run on the late stage or should be supplied by some kinf of writtable
fs, ie tmpfs. The FreeBSD-integrated version uses standard rcorder
annotations (REQUIRE, BEFORE and PROVIDE) and there's no need to change
rc.d scripts
It's not a full init replacement or a kind of services supervision tool.
It only starts or invokes a group of scripts in parallel with resolving
and assuring execution in dependencies order.
Please take a look at the script and patch set for FreeBSD:
https://github.com/cvss/jet9-multitask-init/blob/master/jet9-multitask-init
https://github.com/cvss/jet9-multitask-init/tree/master/examples/freebsd
--
Cyril Vechera
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