Commit graph

128 commits

Author SHA1 Message Date
Aliaksandr Valialkin
1f105dde98
all: allow dynamically reading *AuthKey flag values from files and urls
Examples:

1) -metricsAuthKey=file:///abs/path/to/file - reads flag value from the given absolute filepath
2) -metricsAuthKey=file://./relative/path/to/file - reads flag value from the given relative filepath
3) -metricsAuthKey=http://some-host/some/path?query_arg=abc - reads flag value from the given url

The flag value is automatically updated when the file contents changes.
2024-01-21 22:03:38 +02:00
Aliaksandr Valialkin
7fc2bd0412
app/vmstorage: expose proper types for storage metrics when -metrics.exposeMetadata command-line flag is set
This is a follow-up for 326a77c697
2024-01-16 00:20:37 +02:00
Aliaksandr Valialkin
5106045048
app/vmstorage: deregister storage metrics before stopping the storage
This prevents from possible nil pointer dereference issues when the storage metrics
are read after the storage is stopped.

Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5548
2024-01-15 16:11:45 +02:00
Aliaksandr Valialkin
717c53af27
lib/storage: stop exposing vm_merge_need_free_disk_space metric
This metric confuses users and has no any useful information.

See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/686#issuecomment-1733844128
2023-09-25 16:52:39 +02:00
Aliaksandr Valialkin
24d61bf193
lib/flagutil: add Duration.Milliseconds() convenience function after 0c7d46d637
This function is a faster replacement for Duration.Duration().Milliseconds() call
2023-09-03 10:56:44 +02:00
Dima Lazerka
0c7d46d637
flagutil: Make .Msecs private (#4906)
* Introduce flagutil.Duration

To avoid conversion bugs

* Fix tests

* Clarify documentation re. month=31 days

* Add fasttime.UnixTime() to obtain time.Time

The goal is to refactor out the last usage of `.Msecs`.

* Use fasttime for time.Now()

* wip

- Remove fasttime.UnixTime(), since it doesn't improve code readability and maintainability
- Run `make docs-sync` for syncing changes from README.md to docs/ folder
- Make lib/flagutil.Duration.Msec private
- Rename msecsPerMonth const to msecsPer31Days in order to be consistent with retention31Days

---------

Co-authored-by: Aliaksandr Valialkin <valyala@victoriametrics.com>
2023-09-03 10:33:37 +02:00
Dima Lazerka
e0e856d2e7
Add flagutil.Duration to avoid conversion bugs (#4835)
* Introduce flagutil.Duration

To avoid conversion bugs

* Fix tests

* Comment why not .Seconds()
2023-09-01 09:27:51 +02:00
Nikolay
544fba6826
lib/storage: pre-create timeseries before indexDB rotation (#4652)
* lib/storage: pre-create timeseries before indexDB rotation
during an hour before indexDB rotation start creating records at the next indexDB
it must improve performance during switch for the next indexDB and remove ingestion issues.
Since there is no need for creation new index records for timeseries already ingested into current indexDB
https://github.com/VictoriaMetrics/VictoriaMetrics/issues/4563

* lib/storage: further work on indexdb rotation optimization

- Document the change at docs/CHAGNELOG.md
- Move back various caches from indexDB to Storage. This makes the change less intrusive.
  The dateMetricIDCache now takes into account indexDB generation, so it stores (date, metricID)
  entries for both the current and the next indexDB.
- Consolidate the code responsible for idbNext pre-filling into prefillNextIndexDB() function.
  This improves code readability and maintainability a bit.
- Rewrite and simplify the code responsible for calculating the next retention timestamp.
  Add various tests for corner cases of this code.
- Remove indexdb pre-filling from RegisterMetricNames() function, since this function is rarely called.
  It is OK to add indexdb entries on demand in this function. This simplifies the code.

Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1401

* docs/CHANGELOG.md: refer to https://github.com/VictoriaMetrics/VictoriaMetrics/issues/4563

---------

Co-authored-by: Aliaksandr Valialkin <valyala@victoriametrics.com>
2023-07-22 15:20:21 -07:00
Aliaksandr Valialkin
7094fa38bc
lib/storage: switch from global to per-day index for MetricName -> TSID mapping
Previously all the newly ingested time series were registered in global `MetricName -> TSID` index.
This index was used during data ingestion for locating the TSID (internal series id)
for the given canonical metric name (the canonical metric name consists of metric name plus all its labels sorted by label names).

The `MetricName -> TSID` index is stored on disk in order to make sure that the data
isn't lost on VictoriaMetrics restart or unclean shutdown.

The lookup in this index is relatively slow, since VictoriaMetrics needs to read the corresponding
data block from disk, unpack it, put the unpacked block into `indexdb/dataBlocks` cache,
and then search for the given `MetricName -> TSID` entry there. So VictoriaMetrics
uses in-memory cache for speeding up the lookup for active time series.
This cache is named `storage/tsid`. If this cache capacity is enough for all the currently ingested
active time series, then VictoriaMetrics works fast, since it doesn't need to read the data from disk.

VictoriaMetrics starts reading data from `MetricName -> TSID` on-disk index in the following cases:

- If `storage/tsid` cache capacity isn't enough for active time series.
  Then just increase available memory for VictoriaMetrics or reduce the number of active time series
  ingested into VictoriaMetrics.

- If new time series is ingested into VictoriaMetrics. In this case it cannot find
  the needed entry in the `storage/tsid` cache, so it needs to consult on-disk `MetricName -> TSID` index,
  since it doesn't know that the index has no the corresponding entry too.
  This is a typical event under high churn rate, when old time series are constantly substituted
  with new time series.

Reading the data from `MetricName -> TSID` index is slow, so inserts, which lead to reading this index,
are counted as slow inserts, and they can be monitored via `vm_slow_row_inserts_total` metric exposed by VictoriaMetrics.

Prior to this commit the `MetricName -> TSID` index was global, e.g. it contained entries sorted by `MetricName`
for all the time series ever ingested into VictoriaMetrics during the configured -retentionPeriod.
This index can become very large under high churn rate and long retention. VictoriaMetrics
caches data from this index in `indexdb/dataBlocks` in-memory cache for speeding up index lookups.
The `indexdb/dataBlocks` cache may occupy significant share of available memory for storing
recently accessed blocks at `MetricName -> TSID` index when searching for newly ingested time series.

This commit switches from global `MetricName -> TSID` index to per-day index. This allows significantly
reducing the amounts of data, which needs to be cached in `indexdb/dataBlocks`, since now VictoriaMetrics
consults only the index for the current day when new time series is ingested into it.

The downside of this change is increased indexdb size on disk for workloads without high churn rate,
e.g. with static time series, which do no change over time, since now VictoriaMetrics needs to store
identical `MetricName -> TSID` entries for static time series for every day.

This change removes an optimization for reducing CPU and disk IO spikes at indexdb rotation,
since it didn't work correctly - see https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1401 .

At the same time the change fixes the issue, which could result in lost access to time series,
which stop receving new samples during the first hour after indexdb rotation - see https://github.com/VictoriaMetrics/VictoriaMetrics/issues/2698

The issue with the increased CPU and disk IO usage during indexdb rotation will be addressed
in a separate commit according to https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1401#issuecomment-1553488685

This is a follow-up for 1f28b46ae9
2023-07-13 16:07:30 -07:00
Dmytro Kozlov
24f34347f1
docs: clarify -retentionPeriod flag usage (#4417)
app/vmstorage: clarify the min value for `-retentionPeriod` flag

Co-authored-by: Roman Khavronenko <roman@victoriametrics.com>
2023-06-09 09:46:25 +02:00
Alexander Marshalov
2e494e2375
fixed typos in documentation and commandline flags descriptions (#4275) 2023-05-10 09:50:41 +02:00
Aliaksandr Valialkin
52006149b2
lib/storage: replace OpenStorage() with MustOpenStorage()
Callers of OpenStorage() log the returned error and exit.
The error logging and exit can be performed inside MustOpenStorage()
alongside with printing the stack trace for better debuggability.
This simplifies the code at caller side.
2023-04-14 23:02:40 -07:00
Aliaksandr Valialkin
e1211a1187
app/vmstorage: deprecate -bigMergeConcurrency command-line flag
Improperly configured -bigMergeConcurrency command-line flag usually leads to uncontrolled
growth of unmerged parts, which, in turn, increases CPU usage and query durations.

So it is better deprecating this flag. In rare cases -smallMergeConcurrency command-line flag
can be used instead for controlling the concurrency of background merges.
2023-04-13 20:40:24 -07:00
Aliaksandr Valialkin
0d3f31f60e
lib/storage: follow-up for 39cdc546dd
- Use flag.Duration instead of flagutil.Duration for -snapshotCreateTimeout,
  since the flagutil.Duration is intended mostly for big durations, e.g. days, months and years,
  while the -snapshotCreateTimeout is usually smaller than one hour.
- Add links to https://docs.victoriametrics.com/#how-to-work-with-snapshots in docs/CHANGELOG.md,
  so readers could easily find the corresponding docs when reading the changelog.
- Properly remove all the created directories on unsuccessful attempt to create
  snapshot in Storage.CreateSnapshot().

Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3551
2023-02-27 13:07:38 -08:00
Zakhar Bessarab
39cdc546dd
lib/storage: enhancements for snapshots process (#3873)
* lib/{fs,mergeset,storage}: skip `.must-remove.` dirs when creating snapshot (#3858)

* lib/{mergeset,storage}: add timeout configuration for snapshots creation, remove incomplete snapshots from storage

* docs: fix formatting

* app/vmstorage: add metrics to track status of snapshots

* app/vmstorage: use `vm_http_requests_total` metric for snapshot endpoints metrics, rename new flag to make name more clear

Signed-off-by: Zakhar Bessarab <z.bessarab@victoriametrics.com>

* app/vmstorage: update flag name in docs

Signed-off-by: Zakhar Bessarab <z.bessarab@victoriametrics.com>

* app/vmstorage: reflect new metrics names change in docs

Signed-off-by: Zakhar Bessarab <z.bessarab@victoriametrics.com>

---------

Signed-off-by: Zakhar Bessarab <z.bessarab@victoriametrics.com>
Co-authored-by: Aliaksandr Valialkin <valyala@victoriametrics.com>
2023-02-27 12:12:03 -08:00
Artem Navoiev
7c1daade15
tests: use DebugFlush instead of vmstorage stop. This simplifies the logic and allows to remove test-only methodds (#3694)
Signed-off-by: Artem Navoiev <tenmozes@gmail.com>

Signed-off-by: Artem Navoiev <tenmozes@gmail.com>
2023-01-23 14:45:59 +01:00
Aliaksandr Valialkin
09d7fa2737
lib/{mergeset,storage}: do not slow down concurrently executed queries during assisted merges
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3647
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3641
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/648
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/291
2023-01-16 14:31:52 -08:00
Aliaksandr Valialkin
95ce1ba6ce
lib/httpserver: directly pass flag value to CheckAuthFlag()
There is no sense in passing a pointer to flag value there.

This is a follow-up for 4225a0bd75
2023-01-10 15:52:23 -08:00
Zakhar Bessarab
4225a0bd75
Use httpAuth.* flags as a fallback for endpoints protected by *AuthKey flags (#3582)
* {lib/server, app/}: use `httpAuth.*` flag as fallback for `*AuthKey` if it is not set

* lib/ingestserver/opentsdbhttp: fix opentdb HTTP handler not respecting `httpAuth.*` flags

* Apply suggestions from code review

Co-authored-by: Aliaksandr Valialkin <valyala@victoriametrics.com>
2023-01-10 15:46:13 -08:00
Aliaksandr Valialkin
293e4dc77b
app/{vminsert,vmstorage}: add comments on why storage.AddRows() is called without limiting the number of concurrent calls 2023-01-06 22:40:07 -08:00
Aliaksandr Valialkin
c63755c316
lib/writeconcurrencylimiter: improve the logic behind -maxConcurrentInserts limit
Previously the -maxConcurrentInserts was limiting the number of established client connections,
which write data to VictoriaMetrics. Some of these connections could be idle.
Such connections do not consume big amounts of CPU and RAM, so there is a little sense in limiting
the number of such connections. So now the -maxConcurrentInserts command-line option
limits the number of concurrently executed insert requests, not including idle connections.

It is recommended removing -maxConcurrentInserts command-line option, since the default value
for this option should work good for most cases.
2023-01-06 22:20:19 -08:00
Aliaksandr Valialkin
4de9d35458
lib/flagutil/bytes.go: properly handle values bigger than 2GiB on 32-bit architectures
This fixes handling of values bigger than 2GiB for the following command-line flags:

- -storage.minFreeDiskSpaceBytes
- -remoteWrite.maxDiskUsagePerURL
2022-12-14 19:26:31 -08:00
Aliaksandr Valialkin
d1af6046c7
lib/{mergeset,storage}: do not block small merges by pending big merges - assist with small merges instead
Blocked small merges may result into big number of small parts, which, in turn,
may result in increased CPU and memory usage during queries, since queries need to inspect
all the existing small parts.

The issue has been introduced in 8189770c50

Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3337
2022-12-12 17:00:50 -08:00
Aliaksandr Valialkin
8189770c50
all: add -inmemoryDataFlushInterval command-line flag for controlling the frequency of saving in-memory data to disk
The main purpose of this command-line flag is to increase the lifetime of low-end flash storage
with the limited number of write operations it can perform. Such flash storage is usually
installed on Raspberry PI or similar appliances.

For example, `-inmemoryDataFlushInterval=1h` reduces the frequency of disk write operations
to up to once per hour if the ingested one-hour worth of data fits the limit for in-memory data.

The in-memory data is searchable in the same way as the data stored on disk.
VictoriaMetrics automatically flushes the in-memory data to disk on graceful shutdown via SIGINT signal.
The in-memory data is lost on unclean shutdown (hardware power loss, OOM crash, SIGKILL).

Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3337
2022-12-05 15:16:14 -08:00
Dmytro Kozlov
fb65fb39d2
app/vmstorage: fix potential file inclusion via variable (#3339)
* app/vmstorage: fix potential file inclusion via variable

* app/vmstorage: cleanup
2022-11-17 01:29:43 +02:00
Aliaksandr Valialkin
8e998aa1a1
lib/storage: add support for retention filters (aka multiple retentions for distinct sets of time series)
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/143
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/289
2022-10-24 16:40:20 +03:00
Aliaksandr Valialkin
5e4dfe50c6
lib/storage: subsitute searchTSIDs functions with more lightweight searchMetricIDs function
The searchTSIDs function was searching for metricIDs matching the the given tag filters
and then was locating the corresponding TSID entries for the found metricIDs.

The TSID entries aren't needed when searching for time series names (aka MetricName),
so this commit removes the uneeded TSID search from the implementation of /api/v1/series API.
This improves perfromance of /api/v1/series calls.

This commit also improves performance a bit for /api/v1/query and /api/v1/query_range calls,
since now these calls cache small metricIDs instead of big TSID entries
in the indexdb/tagFilters cache (now this cache is named indexdb/tagFiltersToMetricIDs)
without the need to compress the saved entries in order to save cache space.

This commit also removes concurrency limiter during searching for matching time series,
which was introduced in 8f16388428, since the concurrency
for all the read queries is already limited with -search.maxConcurrentRequests command-line flag.

Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/648
2022-10-23 12:23:47 +03:00
Aliaksandr Valialkin
796aa310c2
app/vmstorage: expose vm_{hourly,daily}_series_limit_{max,current}_series metrics if -storage.max{Hourly,Daily}Series limits are set
These metrics allow alerting when the number of unique series approach the limit.
For example, the following query alerts when the number of series reaches 90% of the configured limit:

    vm_hourly_series_limit_current_series / vm_hourly_series_limit_max_series > 0.9
2022-08-24 13:44:04 +03:00
guidao
91faa152a5
add next retention metric (#2863)
Co-authored-by: wangfeng <wangfeng@zhihu.com>
2022-07-13 12:37:04 +03:00
Aliaksandr Valialkin
e1b8059086
lib/vmselectapi: rename deleteMetrics to more correct deleteSeries 2022-07-06 12:37:54 +03:00
Aliaksandr Valialkin
a60e03b3a7
lib/vmselectapi: use string type for tagKey and tagValuePrefix args at TagValueSuffixes()
This improves the API consistency
2022-07-06 12:37:53 +03:00
Aliaksandr Valialkin
a350d1e81c
lib/storage: return marshaled metric names from SearchMetricNames
Previously SearchMetricNames was returning unmarshaled metric names.
This wasn't great for vmstorage, which should spend additional CPU time
for marshaling the metric names before sending them to vmselect.

While at it, remove possible duplicate metric names, which could occur when
multiple samples for new time series are ingested via concurrent requests.

Also sort the metric names before returning them to the client.
This simplifies debugging of the returned metric names across repeated requests to /api/v1/series
2022-06-28 18:17:15 +03:00
Aliaksandr Valialkin
ba514284f1
lib/storage: add querytracer to more contexts
querytracer has been added to the following storage.Storage methods:
- RegisterMetricNames
- DeleteMetrics
- SearchTagValueSuffixes
- SearchGraphitePaths
2022-06-27 13:45:51 +03:00
Aliaksandr Valialkin
ec7963208d
app/vmselect: accept focusLabel query arg at /api/v1/status/tsdb
This allows filling the seriesCountByFocusLabelValue list in the /api/v1/status/tsdb response
with label values for the specified focusLabel, which contain the highest number of time series.

TODO: add this to Cardinality explorer at VMUI - https://docs.victoriametrics.com/#cardinality-explorer
2022-06-14 18:36:54 +03:00
Aliaksandr Valialkin
374beb350e
app/vmselect: optimize /api/v1/labels and /api/v1/label/.../values handlers when match[] query arg is passed to them 2022-06-12 04:32:13 +03:00
Aliaksandr Valialkin
2bcb960f17
all: improve query tracing coverage for indexdb search
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1403
2022-06-09 20:07:07 +03:00
Roman Khavronenko
642eb1c534
lib/storage: make indexdb/tagFilters cache size configurable (#2667)
The default size of `indexdb/tagFilters` now can be overridden via
`storage.cacheSizeIndexDBTagFilters` flag.
Please, be careful with changing default size since it may
lead to inefficient work of the vmstorage or OOM exceptions.

https://github.com/VictoriaMetrics/VictoriaMetrics/issues/2663
Signed-off-by: hagen1778 <roman@victoriametrics.com>

Co-authored-by: Nikolay <nik@victoriametrics.com>
2022-06-01 10:07:53 +02:00
Aliaksandr Valialkin
41958ed5dd
all: add initial support for query tracing
See https://docs.victoriametrics.com/Single-server-VictoriaMetrics.html#query-tracing

Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1403
2022-06-01 02:29:23 +03:00
Aliaksandr Valialkin
f6d11a49aa
lib/storage: add ability to change the indexdb rotation time offset with -retentionTimezoneOffset command-line flag
This is a follow-up for 0fbf59199a

See https://github.com/VictoriaMetrics/VictoriaMetrics/pull/2574
2022-05-25 16:05:29 +03:00
Roman Khavronenko
331a5d9a17
Code check (#2558)
* vmstorage: make gofmt happy

Signed-off-by: hagen1778 <roman@victoriametrics.com>

* vmalert: make linter happy

Signed-off-by: hagen1778 <roman@victoriametrics.com>
2022-05-09 10:11:56 +02:00
Aliaksandr Valialkin
d6ad8d090d
app/vmstorage: do not allow to set -retentionPeriod smaller than one day
VictoriaMetrics doesn't support retention periods smaller than one day,
so do not allow to set it to small values.

Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/2496
2022-05-07 00:53:01 +03:00
Roman Khavronenko
13efaa42d5
vmstorage: switch to rich duration parser for flag snapshotsMaxAge (#2542)
The switch suppose to allow setting `d`, `w`, `y` duration units.

Signed-off-by: hagen1778 <roman@victoriametrics.com>
2022-05-05 18:43:21 +02:00
Aliaksandr Valialkin
c9e57d8000
app/vmstorage/main.go: reduce the difference with cluster version 2022-05-04 23:56:19 +03:00
Artem Navoiev
37cf509c3a
lib/{storage,flagutil} - Add option for snapshot autoremoval (#2487)
* lib/{storage,flagutil} - Add option for snapshot autoremoval

- add prometheus-like duration as command flag
- add option to delete stale snapshots
- update duration.go flag to re-use own code

* wip

* lib/flagutil: re-use Duration.Set() call in NewDuration

* wip

Co-authored-by: Aliaksandr Valialkin <valyala@victoriametrics.com>
2022-05-02 11:00:15 +03:00
Aliaksandr Valialkin
20bc2a2c44
lib/flagutil: re-use Duration.Set() call in NewDuration 2022-05-02 10:56:39 +03:00
Aliaksandr Valialkin
98129d4a8e
app/vmstorage: expose vm_indexdb_items_added_total and vm_indexdb_items_added_size_bytes_total counters at /metrics page
These counters can be used for monitoring the rate of addition of new entries in indexdb (aka inverted index).

See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/2471
2022-04-21 13:18:39 +03:00
Nikolay
9a88c1a91e
lib/{storage,regexpcache}: replaces regexpCacheMap with LRU cache (#2293)
* lib/{storage,regexpcache}: replaces regexpCacheMap with LRU cache

It should decrease memory usage for regexp caching
with storing cacheEntry by pointer - golang map should be able to effectivly shrink it's size
original issue with this case - unexpected map grows and storage OOM

Apply suggestions from code review

Co-authored-by: Roman Khavronenko <roman@victoriametrics.com>

Adds missing metrics for regexp cache and regexpPrefixes cache

* wip

* wip

Co-authored-by: Aliaksandr Valialkin <valyala@victoriametrics.com>
2022-03-26 12:54:50 +02:00
Aliaksandr Valialkin
6e364e19ef
app/vmselect: add fine-grained limits for the number of returned/scanned time series for various APIs 2022-03-26 11:29:49 +02:00
Roman Khavronenko
b6ed9afd6d
lib: allow to configure cache size by type (#2206)
* lib: allow to configure cache size by type

https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1940
Signed-off-by: hagen1778 <roman@victoriametrics.com>

* Apply suggestions from code review

* wip

Co-authored-by: Aliaksandr Valialkin <valyala@victoriametrics.com>
2022-02-21 13:50:34 +02:00
Roman Khavronenko
cf1a8bce6b
lib/index: reduce read/write load after indexDB rotation (#2177)
* lib/index: reduce read/write load after indexDB rotation

IndexDB in VM is responsible for storing TSID - ID's used for identifying
time series. The index is stored on disk and used by both ingestion and read path.

IndexDB is stored separately to data parts and is global for all stored data.
It can't be deleted partially as VM deletes data parts. Instead, indexDB is
rotated once in `retention` interval.

The rotation procedure means that `current` indexDB becomes `previous`,
and new freshly created indexDB struct becomes `current`. So in any time,
VM holds indexDB for current and previous retention periods.
When time series is ingested or queried, VM checks if its TSID is present
in `current` indexDB. If it is missing, it checks the `previous` indexDB.
If TSID was found, it gets copied to the `current` indexDB. In this way
`current` indexDB stores only series which were active during the retention
period.

To improve indexDB lookups, VM uses a cache layer called `tsidCache`. Both
write and read path consult `tsidCache` and on miss the relad lookup happens.

When rotation happens, VM resets the `tsidCache`. This is needed for ingestion
path to trigger `current` indexDB re-population. Since index re-population
requires additional resources, every index rotation event may cause some extra
load on CPU and disk. While it may be unnoticeable for most of the cases,
for systems with very high number of unique series each rotation may lead
to performance degradation for some period of time.

This PR makes an attempt to smooth out resource usage after the rotation.
The changes are following:
1. `tsidCache` is no longer reset after the rotation;
2. Instead, each entry in `tsidCache` gains a notion of indexDB to which
they belong;
3. On ingestion path after the rotation we check if requested TSID was
found in `tsidCache`. Then we have 3 branches:
3.1 Fast path. It was found, and belongs to the `current` indexDB. Return TSID.
3.2 Slow path. It wasn't found, so we generate it from scratch,
add to `current` indexDB, add it to `tsidCache`.
3.3 Smooth path. It was found but does not belong to the `current` indexDB.
In this case, we add it to the `current` indexDB with some probability.
The probability is based on time passed since the last rotation with some threshold.
The more time has passed since rotation the higher is chance to re-populate `current` indexDB.
The default re-population interval in this PR is set to `1h`, during which entries from
`previous` index supposed to slowly re-populate `current` index.

The new metric `vm_timeseries_repopulated_total` was added to identify how many TSIDs
were moved from `previous` indexDB to the `current` indexDB. This metric supposed to
grow only during the first `1h` after the last rotation.

https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1401

Signed-off-by: hagen1778 <roman@victoriametrics.com>

* wip

* wip

Co-authored-by: Aliaksandr Valialkin <valyala@victoriametrics.com>
2022-02-12 00:30:08 +02:00