Allocations are reduced by implementing custom json parser via fastjson
lib.
The change also re-uses `promInstant` object in attempt to reduce number
of
allocations when parsing big responses, as usually happens with heavy
recording rules.
```
name old allocs/op new allocs/op delta
ParsePrometheusResponse/Instant-10 9.65k ± 0% 5.60k ± 0% ~ (p=1.000 n=1+1)
```
Signed-off-by: hagen1778 <roman@victoriametrics.com>
---------
Signed-off-by: hagen1778 <roman@victoriametrics.com>
* vmalert: add `query_time_alignment` for rule group
1. add `eval_alignment` attribute for group which by default is true. So group rule query stamp will be aligned with interval and propagated to ALERT metrics and the messages for alertmanager;
2. deprecate `datasource.queryTimeAlignment` flag.
https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5049
Adds `eval_offset` attribute for Groups.
If specified, Group will be evaluated at the exact time offset on the range of [0...evaluationInterval].
The setting might be useful for cron-like rules which must be evaluated at specific moments of time.
https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3409
Signed-off-by: Haley Wang <pipilong.25@gmail.com>
Co-authored-by: hagen1778 <roman@victoriametrics.com>
Method `metrics()` now pre-allocates slices for labels
and results from query responses. This reduces the number
of allocations on the hot path for instant requests.
Signed-off-by: hagen1778 <roman@victoriametrics.com>
