Cache client metadata, in order to be improve runtime behaviour under
pressure.
This is inspired by @vcaputo's work, specifically:
https://github.com/systemd/systemd/pull/2280
That code implements related but different semantics.
For a longer explanation what this change implements please have a look
at the long source comment this patch adds to journald-context.c.
After this commit:
# time bash -c 'dd bs=$((1024*1024)) count=$((1*1024)) if=/dev/urandom | systemd-cat'
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB, 1.0 GiB) copied, 11.2783 s, 95.2 MB/s
real 0m11.283s
user 0m0.007s
sys 0m6.216s
Before this commit:
# time bash -c 'dd bs=$((1024*1024)) count=$((1*1024)) if=/dev/urandom | systemd-cat'
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB, 1.0 GiB) copied, 52.0788 s, 20.6 MB/s
real 0m52.099s
user 0m0.014s
sys 0m7.170s
As side effect, this corrects the journal's rate limiter feature: we now
always use the unit name as key for the ratelimiter.
Lennart Poettering
22e3a02b9d