2 Commits (8abe080fd6d04dc5efb074ee0764a9bfd39c82d2)

Author	SHA1	Message	Date
Salva Corts	c6fbff26e1	Add config to avoid caching stats for recent data (#9537) ... **What this PR does / why we need it**: When we query the stats for recent data, we query both the ingesters and the index gateways for the stats. ebdb2b1800/pkg/storage/async_store.go (L112-L114) ebdb2b1800/pkg/storage/async_store.go (L126-L127) Then we merge all the responses, which means summing up all the stats ebdb2b1800/pkg/storage/async_store.go (L157-L158) ebdb2b1800/pkg/storage/stores/index/stats/stats.go (L23-L26) Because we have a replication factor of 3, this means that we will get the stats from the ingesters repeated up to 3 times, hence inflating the stats. In the stats cache, we store the stats for a given matcher set for the whole day, then we extract the stats from the cache by the factor of time from the request that is stored in the cache: 336283acad/pkg/querier/queryrange/index_stats_cache.go (L33) 336283acad/pkg/querier/queryrange/index_stats_cache.go (L40) Inflated stats for recent data will be cached, so subsequent stats extracted from the cache will be inflated regardless of the time. This PR adds a new per-tenant limit `max_stats_cache_freshness` to not cache requests with an end time that falls within Now minus this duration. Here's a scenario illustrating this. The graphs below show the bytes stats queried in the sharding middleware. We are running a log filter query that won't match any log, every 5 seconds with a length of 3h.  As can be seen, after enabling the stats cache and configuring`do_not_cache_request_within` to not cache stats for requests within 30m, the bytes stats used in the sharding middleware stopped increasing. In both cases the stats cache hit ration was 100%.  **Special notes for your reviewer**: - Blocked by https://github.com/grafana/loki/pull/9535 - Note that this PR doesn't fix the root issue of inflated stats form the ingesters, but rather buys us some time to work on that. **Checklist** - [x] Reviewed the [`CONTRIBUTING.md`](https://github.com/grafana/loki/blob/main/CONTRIBUTING.md) guide (**required**) - [x] Documentation added - [x] Tests updated - [ ] `CHANGELOG.md` updated - [ ] Changes that require user attention or interaction to upgrade are documented in `docs/sources/upgrading/_index.md` - [ ] For Helm chart changes bump the Helm chart version in `production/helm/loki/Chart.yaml` and update `production/helm/loki/CHANGELOG.md` and `production/helm/loki/README.md`. [Example PR](d10549e3ec)	3 years ago
Salva Corts	fd16425062	Cache index stats requests (#8972) ... **What this PR does / why we need it**: As described in https://github.com/grafana/loki/issues/8973, we are substantially increasing the load of index stat requests we sent to our index gateways. Many of these requests should be easily re-used by caching them. This PR adds caching for index stat requests by reusing the results cache. Here's a demo ([source][1]):  **Which issue(s) this PR fixes**: Fixes https://github.com/grafana/loki/issues/8973 **Special notes for your reviewer**: **Checklist** - [x] Reviewed the [`CONTRIBUTING.md`](https://github.com/grafana/loki/blob/main/CONTRIBUTING.md) guide (**required**) - [ ] Documentation added - [x] Tests updated - [x] `CHANGELOG.md` updated - [ ] Changes that require user attention or interaction to upgrade are documented in `docs/sources/upgrading/_index.md` [1]: https://ops.grafana-ops.net/d/afcaef21-e5ad-49e7-ab06-42a9d7d915eb/index-stats?orgId=1&var-datasource=dev-cortex&var-cluster=dev-eu-west-2&var-namespace=loki-dev-009&var-loki_datasource=Grafana%20Logging&from=1680259907288&to=1680260431814&var-operation=All --------- Co-authored-by: Owen Diehl <ow.diehl@gmail.com>	3 years ago