Tried a today's git checkout on one of our small virtual 10.2 boxes
with not many services. The installation is almost trivial and a
reboot went without any problems. Time for a reboot was shrunk by
about 10 seconds (which is understandable with a small number of
services). Very good, almost too good to be true for such fairly
small and non-intrusive piece of shell/awk scripting - thanks!
Mark
2015-10-16 20:37, Cyril Vechera wrote:
On 10/16/2015 07:06 PM, Mark Felder wrote:
On Fri, Oct 2, 2015, at 11:08, Cyril Vechera wrote:
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
Your first link is a 404, but this looks really nice!
In the last commit (v1.3.0) I've renamed 'jet9-multitask-init' to
'jet9-multitask-flow' to avoid confusion with naming, because it's not
as it seems, from name, an init replacement, but just a parallel task
launcher. And now the actual repository URL is
https://github.com/cvss/jet9-multitask-flow
In this commit I've complete the FreeBSD compatibility. Now a script
or dependency name can include minuses `-` and dots `.` (the first
stone I stumbled over was ftp-proxy). And I've cleaned up the main
script code
https://github.com/cvss/jet9-multitask-flow/jet9-multitask-flow and
have split it to more functions that can be redefined. So it's now
easier to rewrite dependency extraction for FreeBSD rc-scripts -
current implementation is too rough and takes three 'awk' runs for
each rc-script. The last is not only time loss, but as DMarck
mentioned before, using awk restricts parallel rc to be run only after
FILESYSTEMS stage is done. Maybe it would be better to add to the
rcorder(8) some new option to dump the gathered dependencies in
tsort-compatible listing and insert them directly to flow execution
plan.
I've also added rc.conf variable `rc_parallel` to turn on and off
parallel execution. There's a risk to discover an incomplete
dependency annotations in some rc-scripts that earlier were masked by
serial execution. I've done some checks by enabling as much rc.conf
variables as possible to start more rc-scripts, and didn't found any
error. But it looks too good to be true and I'm afraid that it's just
to poor testing. I think if some ordering conflict will be found, it
could be worked-around with introducing a white-list for script names
that must be run only in sequentially.
So it remained first to check if it really works in different
conditions.
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