This change is made in attempt to reduce memory usage by vmalert when
parsing big instant responses from VM/Prometheus.
In
a5c427bac4
vmalert switched from std json lib to fastjson lib in order to reduce
amount of allocations, as according to highloaded profiles of vmalert
the CPU is mostly spent on GC.
But switching to fastjson resulted into excessive memory usage for cases
when vmalert has to parse long json lines, which usually happens when
instant response contains many `metric` objects.
In this change we do a mixed parsing:
1. Slice of `metric` objects is parsed with std lib to keep mem low
2. Each `metric` object is parsed with fastjson to reduce allocs
The benchmark results are the following:
```
pkg: github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/datasource
BenchmarkParsePrometheusResponse/Instant_std+fastjson-10 1760 668959 ns/op 280147 B/op 5781 allocs/op
MBs allocated at heap: 493.078392
mallocs: 18655472
BenchmarkParsePrometheusResponse/Instant_fastjson-10 6109 198258 ns/op 172839 B/op 5548 allocs/op
MBs allocated at heap: 1056.384464
mallocs: 34457184
BenchmarkParsePrometheusResponse/Instant_std-10 1287 950987 ns/op 451677 B/op 9619 allocs/op
MBs allocated at heap: 580.802976
mallocs: 13351636
```
The benchmark function code with mem measurement is available here
https://gist.github.com/hagen1778/b9c3ca7f8ca7d6b21aec9777112c5810
The benchmark contains 3 results:
1. Instant_std+fastjson is the implementation in this change
2. Instant_fastjson-10 is the implementation from
a5c427bac4
3. BenchmarkParsePrometheusResponse/Instant_std-10 is implementation
before
a5c427bac4
According to these results, this new implementation is slower than
previous, but faster than before switching to fastjson. It also has
lower number of allocations and roughly the same memory allocation on
heap with GC turned off.
---------
Other changes:
1. rm BenchmarkMetrics as it doesn't measure anything
2. simplify BenchmarkParsePrometheusResponse into
BenchmarkPromInstantUnmarshal
### Describe Your Changes
Please provide a brief description of the changes you made. Be as
specific as possible to help others understand the purpose and impact of
your modifications.
### Checklist
The following checks are **mandatory**:
- [ ] My change adheres [VictoriaMetrics contributing
guidelines](https://docs.victoriametrics.com/contributing/).
Signed-off-by: hagen1778 <roman@victoriametrics.com>
'any' type is supported starting from Go1.18. Let's consistently use it
instead of 'interface{}' type across the code base, since `any` is easier to read than 'interface{}'.
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>
vmalert: allow disabling of `step` param attached to instant queries
This might be useful for using vmalert with datasources that to not support this param,
unlike VictoriaMetrics.
See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/4573
Signed-off-by: hagen1778 <roman@victoriametrics.com>
app/vmalert: detect alerting rules which don't match any series at all
vmalert starts to understand /query responses which contain object:
```
"stats":{"seriesFetched": "42"}
```
If object is present, vmalert parses it and populates a new field
`SeriesFetched`. This field is then used to populate the new metric
`vmalert_alerting_rules_last_evaluation_series_fetched` and to
display warnings in the vmalert's UI.
If response doesn't contain the new object (Prometheus or
VictoriaMetrics earlier than v1.90), then `SeriesFetched=nil`.
In this case, UI will contain no additional warnings.
And `vmalert_alerting_rules_last_evaluation_series_fetched` will
be set to `-1`. Negative value of the metric will help to compile
correct alerting rule in follow-up.
Thanks for the initial implementation to @Haleygo
See https://github.com/VictoriaMetrics/VictoriaMetrics/pull/4056
See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/4039
Signed-off-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>
The recent change in modifying default value
of `datasource.queryStep` flag resulted in situation
where replay mode was always running queries with
step=`datasource.queryStep`. When it should always
use rule's evaluation interval.
The fix is related not to replay mode only, but
for all Range requests. Now step param is set
individually for each mode.
Signed-off-by: hagen1778 <roman@victoriametrics.com>
Signed-off-by: hagen1778 <roman@victoriametrics.com>
* vmalert: add support for `sortByLabel` template function
* vmalert: update API according to Prometheus conformance program
The changes to the API, field names and URL path has been made
according to the Prometheus specification for `alert_generator`
https://github.com/prometheus/compliance/blob/main/alert_generator/specification.md
* vmalert: fix the timestamp of the evaluated rules
The timestamp used for alert's `EndsAt` was calculated
before sending the notification. While the correct way
is to use the timestamp taken right before rules evaluation.
* vmalert: add `-datasource.queryTimeAlignment` flag
The flag is supposed to provide ability to disable `time`
param alignment when executing rules. By default, this flag
is enabled, so it remains backward compatible.
The flag was introduced to achieve better compatibility
with Prometheus behaviour according to https://github.com/prometheus/compliance/blob/main/alert_generator/specification.md
Signed-off-by: hagen1778 <roman@victoriametrics.com>
When using `vmalert` with older Prometheus versions, the passed
`step=2m` may be parsed by Prometheus with an err: "cannot parse \"2m0s\" to a valid duration".
In order to improve compatibility vmalert will always convert step duration to seconds.
https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1943
Signed-off-by: hagen1778 <roman@victoriametrics.com>
* vmalert: introduce additional HTTP URL params per-group configuration
The new group field `params` allows to configure custom HTTP URL params
per each group. These params will be applied to every request before
executing rule's expression. Hot config reload is also supported.
Field `extra_filter_labels` was deprecated in favour of `params` field.
vmalert will print deprecation log message if config file contains
the deprecated field.
`params` fields are supported by both Prometheus and Graphite datasource types.
Signed-off-by: hagen1778 <roman@victoriametrics.com>
* vmalert: provide more examples for `params` field
Signed-off-by: hagen1778 <roman@victoriametrics.com>
* vmalert: set higher priority for `params` setting
If there would be a conflict between URL params set in `datasource.url` flag
and params in group definition the latter will have higher priority.
Signed-off-by: hagen1778 <roman@victoriametrics.com>
* vmalert: allow extra GET params in datasource package
ExtraParams will be added as GET params to every HTTP request made by datasource.
The `roundDigits` param, for example, was substituted by corresponding extra param.
* vmalert: add nocache=1 param for replay process
The `nocache=1` param is VictoriaMetrics specific parameter which prevents it
from caching and boundaries aligning for queries. We set it to avoid cache
pollution in `replay` mode and also to avoid unnecessary time range boundaries
alignment.
* vmalert: mention nocache=1 in replay description
* vmalert: fix bug with unused param
* vmalert: fix mistake with object reuse while parsing response
During the refactoring, the wrong optimisations was applied in
parse function which caused metric fields reset. The change removes
optimisation.
https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1369
* vmalert: add test to cover multiple metrics in one response
* vmalert: support rules backfilling (aka `replay`)
vmalert can `replay` configured rules in the past
and backfill results via remote write protocol.
It supports MetricsQL/PromQL storage as data source,
and can backfill data to remote write compatible
storage.
Supports recording and alerting rules `replay`. See more
details in README.
https://github.com/VictoriaMetrics/VictoriaMetrics/issues/836
* vmalert: review fixes
* vmalert: readme fixes
