Commit graph

37 commits

Author SHA1 Message Date
Ganesh Vernekar 83d738e263
Fix 'invalid magic number 0' bug (#11338)
Signed-off-by: Ganesh Vernekar <ganeshvern@gmail.com>
2022-09-28 21:43:58 +05:30
Jesus Vazquez c1b669bf9b
Add out-of-order sample support to the TSDB (#11075)
* Introduce out-of-order TSDB support

This implementation is based on this design doc:
https://docs.google.com/document/d/1Kppm7qL9C-BJB1j6yb6-9ObG3AbdZnFUBYPNNWwDBYM/edit?usp=sharing

This commit adds support to accept out-of-order ("OOO") sample into the TSDB
up to a configurable time allowance. If OOO is enabled, overlapping querying
are automatically enabled.

Most of the additions have been borrowed from
https://github.com/grafana/mimir-prometheus/
Here is the list ist of the original commits cherry picked
from mimir-prometheus into this branch:
- 4b2198d7ec
- 2836e5513f
- 00b379c3a5
- ff0dc75758
- a632c73352
- c6f3d4ab33
- 5e8406a1d4
- abde1e0ba1
- e70e769889
- df59320886

Co-authored-by: Jesus Vazquez <jesus.vazquez@grafana.com>
Co-authored-by: Ganesh Vernekar <ganeshvern@gmail.com>
Co-authored-by: Dieter Plaetinck <dieter@grafana.com>
Signed-off-by: Jesus Vazquez <jesus.vazquez@grafana.com>

* gofumpt files

Signed-off-by: Jesus Vazquez <jesus.vazquez@grafana.com>

* Add license header to missing files

Signed-off-by: Jesus Vazquez <jesus.vazquez@grafana.com>

* Fix OOO tests due to existing chunk disk mapper implementation

Signed-off-by: Jesus Vazquez <jesus.vazquez@grafana.com>

* Fix truncate int overflow

Signed-off-by: Jesus Vazquez <jesus.vazquez@grafana.com>

* Add Sync method to the WAL and update tests

Signed-off-by: Jesus Vazquez <jesus.vazquez@grafana.com>

* remove useless sync

Signed-off-by: Jesus Vazquez <jesus.vazquez@grafana.com>

* Update minOOOTime after truncating Head

* Update minOOOTime after truncating Head

Signed-off-by: Ganesh Vernekar <ganeshvern@gmail.com>

* Fix lint

Signed-off-by: Ganesh Vernekar <ganeshvern@gmail.com>

* Add a unit test

Signed-off-by: Ganesh Vernekar <ganeshvern@gmail.com>
Signed-off-by: Jesus Vazquez <jesus.vazquez@grafana.com>

* Load OutOfOrderTimeWindow only once per appender

Signed-off-by: Jesus Vazquez <jesus.vazquez@grafana.com>

* Fix OOO Head LabelValues and PostingsForMatchers

Signed-off-by: Jesus Vazquez <jesus.vazquez@grafana.com>

* Fix replay of OOO mmap chunks

Signed-off-by: Ganesh Vernekar <ganeshvern@gmail.com>

* Remove unnecessary err check

Signed-off-by: Jesus Vazquez <jesus.vazquez@grafana.com>

* Prevent panic with ApplyConfig

Signed-off-by: Ganesh Vernekar 15064823+codesome@users.noreply.github.com
Signed-off-by: Jesus Vazquez <jesus.vazquez@grafana.com>

* Run OOO compaction after restart if there is OOO data from WBL

Signed-off-by: Ganesh Vernekar 15064823+codesome@users.noreply.github.com
Signed-off-by: Jesus Vazquez <jesus.vazquez@grafana.com>

* Apply Bartek's suggestions

Co-authored-by: Bartlomiej Plotka <bwplotka@gmail.com>
Signed-off-by: Jesus Vazquez <jesus.vazquez@grafana.com>

* Refactor OOO compaction

Signed-off-by: Ganesh Vernekar <ganeshvern@gmail.com>

* Address comments and TODOs

- Added a comment explaining why we need the allow overlapping
  compaction toggle
- Clarified TSDBConfig OutOfOrderTimeWindow doc
- Added an owner to all the TODOs in the code

Signed-off-by: Jesus Vazquez <jesus.vazquez@grafana.com>

* Run go format

Signed-off-by: Jesus Vazquez <jesus.vazquez@grafana.com>

* Fix remaining review comments

Signed-off-by: Ganesh Vernekar <ganeshvern@gmail.com>

* Fix tests

Signed-off-by: Ganesh Vernekar <ganeshvern@gmail.com>

* Change wbl reference when truncating ooo in TestHeadMinOOOTimeUpdate

Signed-off-by: Jesus Vazquez <jesus.vazquez@grafana.com>

* Fix TestWBLAndMmapReplay test failure on windows

Signed-off-by: Ganesh Vernekar <ganeshvern@gmail.com>

* Address most of the feedback

Signed-off-by: Ganesh Vernekar <ganeshvern@gmail.com>

* Refactor the block meta for out of order

Signed-off-by: Ganesh Vernekar <ganeshvern@gmail.com>

* Fix windows error

Signed-off-by: Ganesh Vernekar <ganeshvern@gmail.com>

* Fix review comments

Signed-off-by: Ganesh Vernekar <ganeshvern@gmail.com>

Signed-off-by: Jesus Vazquez <jesus.vazquez@grafana.com>
Signed-off-by: Ganesh Vernekar <ganeshvern@gmail.com>
Signed-off-by: Ganesh Vernekar 15064823+codesome@users.noreply.github.com
Co-authored-by: Ganesh Vernekar <15064823+codesome@users.noreply.github.com>
Co-authored-by: Ganesh Vernekar <ganeshvern@gmail.com>
Co-authored-by: Dieter Plaetinck <dieter@grafana.com>
Co-authored-by: Oleg Zaytsev <mail@olegzaytsev.com>
Co-authored-by: Bartlomiej Plotka <bwplotka@gmail.com>
2022-09-20 22:35:50 +05:30
Łukasz Mierzwa 88f9b248b4
Correctly format error message (#10669)
Signed-off-by: Łukasz Mierzwa <l.mierzwa@gmail.com>
2022-05-06 00:42:31 +02:00
Matthieu MOREL e2ede285a2
refactor: move from io/ioutil to io and os packages (#10528)
* refactor: move from io/ioutil to io and os packages
* use fs.DirEntry instead of os.FileInfo after os.ReadDir

Signed-off-by: MOREL Matthieu <matthieu.morel@cnp.fr>
2022-04-27 11:24:36 +02:00
Mauro Stettler b025390cb4
Disable chunk write queue by default, allow user to configure the exact size (#10425)
* Disable chunk write queue by default

Signed-off-by: Mauro Stettler <mauro.stettler@gmail.com>

* update flag description

Signed-off-by: Mauro Stettler <mauro.stettler@gmail.com>
2022-03-11 17:26:59 +01:00
Ganesh Vernekar 24827782cb
Fix panics when m-mapping head chunks (#10316)
* Fix panics when m-mapping head chunks

Signed-off-by: Ganesh Vernekar <ganeshvern@gmail.com>

* Fix review comments

Signed-off-by: Ganesh Vernekar <ganeshvern@gmail.com>

* Fix reviews

Signed-off-by: Ganesh Vernekar <ganeshvern@gmail.com>
2022-02-22 20:35:15 +05:30
Mauro Stettler bf959b36cb
Nits after PR 10051 merge (#10159)
Signed-off-by: Marco Pracucci <marco@pracucci.com>

Co-authored-by: Marco Pracucci <marco@pracucci.com>
2022-01-19 20:20:35 +05:30
Ganesh Vernekar 129ed4ec8b
Fix Example() function in TSDB (#10153)
* Fix Example() function in TSDB

Signed-off-by: Ganesh Vernekar <ganeshvern@gmail.com>

* Fix tests

Signed-off-by: Ganesh Vernekar <ganeshvern@gmail.com>
2022-01-11 17:24:03 +05:30
Mauro Stettler 0df3489275
Write chunks via queue, predicting the refs (#10051)
* Write chunks via queue, predicting the refs

Our load tests have shown that there is a latency spike in the
remote write handler whenever the head chunks need to be written,
because chunkDiskMapper.WriteChunk() blocks until the chunks are written
to disk.

This adds a queue to the chunk disk mapper which makes the WriteChunk()
method non-blocking unless the queue is full. Reads can still be served
from the queue.

Signed-off-by: Mauro Stettler <mauro.stettler@gmail.com>

* address PR feeddback

Signed-off-by: Mauro Stettler <mauro.stettler@gmail.com>

* initialize metrics without .Add(0)

Signed-off-by: Mauro Stettler <mauro.stettler@gmail.com>

* change isRunningMtx to normal lock

Signed-off-by: Mauro Stettler <mauro.stettler@gmail.com>

* do not re-initialize chunkrefmap

Signed-off-by: Mauro Stettler <mauro.stettler@gmail.com>

* update metric outside of lock scope

Signed-off-by: Mauro Stettler <mauro.stettler@gmail.com>

* add benchmark for adding job to chunk write queue

Signed-off-by: Mauro Stettler <mauro.stettler@gmail.com>

* remove unnecessary "success" var

Signed-off-by: Mauro Stettler <mauro.stettler@gmail.com>

* gofumpt -extra

Signed-off-by: Mauro Stettler <mauro.stettler@gmail.com>

* avoid WithLabelValues call in addJob

Signed-off-by: Mauro Stettler <mauro.stettler@gmail.com>

* format comments

Signed-off-by: Mauro Stettler <mauro.stettler@gmail.com>

* addressing PR feedback

Signed-off-by: Mauro Stettler <mauro.stettler@gmail.com>

* rename cutExpectRef to cutAndExpectRef

Signed-off-by: Mauro Stettler <mauro.stettler@gmail.com>

* use head.Init() instead of .initTime()

Signed-off-by: Mauro Stettler <mauro.stettler@gmail.com>

* address PR feedback

Signed-off-by: Mauro Stettler <mauro.stettler@gmail.com>

* PR feedback

Co-authored-by: Ganesh Vernekar <15064823+codesome@users.noreply.github.com>
Signed-off-by: Mauro Stettler <mauro.stettler@gmail.com>

* update test according to PR feedback

Signed-off-by: Mauro Stettler <mauro.stettler@gmail.com>

* replace callbackWg -> awaitCb

Signed-off-by: Mauro Stettler <mauro.stettler@gmail.com>

* better test of truncation with empty files

Signed-off-by: Mauro Stettler <mauro.stettler@gmail.com>

* replace callbackWg -> awaitCb

Signed-off-by: Mauro Stettler <mauro.stettler@gmail.com>

Co-authored-by: Ganesh Vernekar <15064823+codesome@users.noreply.github.com>
2022-01-10 13:36:45 +00:00
Dieter Plaetinck 0fac9bb859
Add basic initial developer docs for TSDB (#9451)
* Add basic initial developer docs for TSDB

There's a decent amount of content already out there (blog posts,
conference talks, etc), but:
* when they get stale, they don't tend to get updated
* they still leave me with questions that I'ld like to answer
  for developers (like me) who want to use, or work with, TSDB

What I propose is developer docs inside the prometheus
repository.  Easy to find and harness the power of the community
to expand it and keep it up to date.

* perfect is the enemy of good.  Let's have a base and incrementally improve
* Markdown docs should be broad but not too deep.  Source code comments
  can complement them, and are the ideal place for implementation details.

Signed-off-by: Dieter Plaetinck <dieter@grafana.com>

* use example code that works out of the box

Signed-off-by: Dieter Plaetinck <dieter@grafana.com>

* Apply suggestions from code review

Co-authored-by: Ganesh Vernekar <15064823+codesome@users.noreply.github.com>
Signed-off-by: Dieter Plaetinck <dieter@grafana.com>

* PR feedback

Signed-off-by: Dieter Plaetinck <dieter@grafana.com>

* more docs

Signed-off-by: Dieter Plaetinck <dieter@grafana.com>

* PR feedback

Signed-off-by: Dieter Plaetinck <dieter@grafana.com>

* Apply suggestions from code review

Signed-off-by: Dieter Plaetinck <dieter@grafana.com>

Co-authored-by: Bartlomiej Plotka <bwplotka@gmail.com>

* Apply suggestions from code review

Signed-off-by: Dieter Plaetinck <dieter@grafana.com>

Co-authored-by: Ganesh Vernekar <15064823+codesome@users.noreply.github.com>

* feedback

Signed-off-by: Dieter Plaetinck <dieter@grafana.com>

* Update tsdb/docs/usage.md

Signed-off-by: Dieter Plaetinck <dieter@grafana.com>

Co-authored-by: Ganesh Vernekar <15064823+codesome@users.noreply.github.com>

* final tweaks

Signed-off-by: Dieter Plaetinck <dieter@grafana.com>

* workaround docs versioning issue

Signed-off-by: Dieter Plaetinck <dieter@grafana.com>

* Move example code to real executable, testable example.

Signed-off-by: Dieter Plaetinck <dieter@grafana.com>

* cleanup example test and make sure it always reproduces

Signed-off-by: Dieter Plaetinck <dieter@grafana.com>

* obtain temp dir in a way that works with older Go versions

Signed-off-by: Dieter Plaetinck <dieter@grafana.com>

* Fix Ganesh's comments

Signed-off-by: Ganesh Vernekar <ganeshvern@gmail.com>

Co-authored-by: Ganesh Vernekar <15064823+codesome@users.noreply.github.com>
Co-authored-by: Bartlomiej Plotka <bwplotka@gmail.com>
Co-authored-by: Ganesh Vernekar <ganeshvern@gmail.com>
2021-11-17 15:51:27 +05:30
Mauro Stettler 8a4f659126 fix error message
Signed-off-by: Mauro Stettler <mauro.stettler@gmail.com>
2021-11-12 21:45:46 +01:00
Dieter Plaetinck cda025b5b5
TSDB: demistify SeriesRefs and ChunkRefs (#9536)
* TSDB: demistify seriesRefs and ChunkRefs

The TSDB package contains many types of series and chunk references,
all shrouded in uint types.  Often the same uint value may
actually mean one of different types, in non-obvious ways.

This PR aims to clarify the code and help navigating to relevant docs,
usage, etc much quicker.

Concretely:

* Use appropriately named types and document their semantics and
  relations.
* Make multiplexing and demuxing of types explicit
  (on the boundaries between concrete implementations and generic
  interfaces).
* Casting between different types should be free.  None of the changes
  should have any impact on how the code runs.

TODO: Implement BlockSeriesRef where appropriate (for a future PR)

Signed-off-by: Dieter Plaetinck <dieter@grafana.com>

* feedback

Signed-off-by: Dieter Plaetinck <dieter@grafana.com>

* agent: demistify seriesRefs and ChunkRefs

Signed-off-by: Dieter Plaetinck <dieter@grafana.com>
2021-11-06 15:40:04 +05:30
Mateusz Gozdek 1a6c2283a3 Format Go source files using 'gofumpt -w -s -extra'
Part of #9557

Signed-off-by: Mateusz Gozdek <mgozdekof@gmail.com>
2021-11-02 19:52:34 +01:00
Dieter Plaetinck d5afe0a577
TSDB: Use a dedicated head chunk reference type (#9501)
* Use dedicated Ref type

Throughout the code base, there are reference types masked as
regular integers.  Let's use dedicated types.  They are
equivalent, but clearer semantically.
This also makes it trivial to find where they are used,
and from uses, find the centralized docs.

Signed-off-by: Dieter Plaetinck <dieter@grafana.com>

* postpone some work until after possible return

Signed-off-by: Dieter Plaetinck <dieter@grafana.com>

* clarify

Signed-off-by: Dieter Plaetinck <dieter@grafana.com>

* rename feedback

Signed-off-by: Dieter Plaetinck <dieter@grafana.com>

* skip header is up to caller

Signed-off-by: Dieter Plaetinck <dieter@grafana.com>
2021-10-13 17:44:32 +05:30
jinglina 1a430e5f89
remove redundant parentheses (#9134)
Signed-off-by: jinglina <jinglinax@163.com>
2021-07-29 18:26:57 +05:30
Marco Pracucci 4b49ffbad5
Stop the bleed on chunk mapper panic (#8723)
* Added test to reproduce panic on TSDB head chunks truncated while querying

Signed-off-by: Marco Pracucci <marco@pracucci.com>

* Added test for Querier too

Signed-off-by: Marco Pracucci <marco@pracucci.com>

* Stop the bleed on mmap-ed head chunks panic

Signed-off-by: Marco Pracucci <marco@pracucci.com>

* Lower memory pressure in tests to ensure it doesn't OOM

Signed-off-by: Marco Pracucci <marco@pracucci.com>

* Skip TestQuerier_ShouldNotPanicIfHeadChunkIsTruncatedWhileReadingQueriedChunks

Signed-off-by: Marco Pracucci <marco@pracucci.com>

* Experiment to not trigger runtime.GC() continuously

Signed-off-by: Marco Pracucci <marco@pracucci.com>

* Try to fix test in CI

Signed-off-by: Marco Pracucci <marco@pracucci.com>

* Do not call runtime.GC() at all

Signed-off-by: Marco Pracucci <marco@pracucci.com>

* I have no idea why it's failing in CI, skipping tests

Signed-off-by: Marco Pracucci <marco@pracucci.com>
2021-05-06 14:18:59 -06:00
Bartlomiej Plotka 8bf7bc68f1
Fixed TestChunkDiskMapper_WriteChunk_Chunk_IterateChunks for go1.16 (#8538)
Fixes https://github.com/prometheus/prometheus/issues/8403

Signed-off-by: Bartlomiej Plotka <bwplotka@gmail.com>
2021-02-25 14:38:12 +05:30
Guangwen Feng e2cd6c5f57 Fix golint issue caused by typo
Signed-off-by: Guangwen Feng <fenggw-fnst@cn.fujitsu.com>
2021-01-06 15:54:35 +08:00
Marco Pracucci db19e05d93
Add option to customise head chunks write buffer size (#8201)
* Add option to customise head chunks write buffer size

Signed-off-by: Marco Pracucci <marco@pracucci.com>

* Fixed tests

Signed-off-by: Marco Pracucci <marco@pracucci.com>
2020-11-19 18:30:47 +05:30
Julien Pivotto 8bc369bf9b
Calculate head chunk size based on actual disk usage (#8139)
Signed-off-by: Julien Pivotto <roidelapluie@inuits.eu>
2020-11-03 15:34:59 +05:30
Bartlomiej Plotka 3d8826a3d4
MultiError: Refactored MultiError for more concise and safe usage. (#8066)
* MultiError: Refactored MultiError for more concise and safe usage.

* Less lines
* Goland IDE was marking every usage of old MultiError "potential nil" error
* It was easy to forgot using Err() when error was returned, now it's safely assured on compile time.

NOTE: Potentially I would rename package to merrors. (: In different PR.

Signed-off-by: Bartlomiej Plotka <bwplotka@gmail.com>

* Addressed review comments.

Signed-off-by: Bartlomiej Plotka <bwplotka@gmail.com>

* Addressed comments.

Signed-off-by: Bartlomiej Plotka <bwplotka@gmail.com>

* Fix after rebase.

Signed-off-by: Bartlomiej Plotka <bwplotka@gmail.com>
2020-10-28 15:24:58 +00:00
Julien Pivotto 4e5b1722b3
Move away from testutil, refactor imports (#8087)
Signed-off-by: Julien Pivotto <roidelapluie@inuits.eu>
2020-10-22 11:00:08 +02:00
Ganesh Vernekar 2624d827fa
Read repair empty last file in chunks_head (#8061)
* Read repair empty file in chunks_head

Signed-off-by: Ganesh Vernekar <cs15btech11018@iith.ac.in>

* Refactor and introduce repairLastChunkFile

Signed-off-by: Ganesh Vernekar <cs15btech11018@iith.ac.in>

* Attempt windows test fix

Signed-off-by: Ganesh Vernekar <cs15btech11018@iith.ac.in>

* Fix review comments

Signed-off-by: Ganesh Vernekar <cs15btech11018@iith.ac.in>

* Fix review comments

Signed-off-by: Ganesh Vernekar <cs15btech11018@iith.ac.in>
2020-10-21 18:27:13 +05:30
Ganesh Vernekar c806262206
Fix 'chunks.HeadReadWriter: maxt of the files are not set' error (#7856)
* Fix chunks.HeadReadWriter: maxt of the files are not set

Signed-off-by: Ganesh Vernekar <cs15btech11018@iith.ac.in>
2020-08-26 19:59:18 +02:00
Yukun Sun cfd4e05c9e
fix: return a corruption error when iterator function find a chunk that is out of sequence (#7855)
Signed-off-by: sunyukun <sunyukun@didiglobal.com>

Co-authored-by: sunyukun <sunyukun@didiglobal.com>
2020-08-26 20:36:27 +05:30
Max Neverov bb5c6b38e2
Fix Possible Race Condition in TSDB (#7815)
* Replace tsdb chunk mapper size with atomic; protect mmappedChunkFiles with read path mutex on DeleteCorrupted

Signed-off-by: Max Neverov <neverov.max@gmail.com>

* PR fixes

Signed-off-by: Max Neverov <neverov.max@gmail.com>
2020-08-26 14:22:48 +05:30
Javier Palomo Almena 348ff4285f
tsdb: Replace sync/atomic with uber-go/atomic in tsdb (#7659)
* tsdb/chunks: Replace sync/atomic with uber-go/atomic

Signed-off-by: Javier Palomo <javier.palomo.almena@gmail.com>

* tsdb/heaad: Replace sync/atomic with uber-go/atomic

Signed-off-by: Javier Palomo <javier.palomo.almena@gmail.com>

* vendor: Make go.uber.org/atomic a direct dependency

There is no modifications to go.sum and vendor/ because
it was already vendored.

Signed-off-by: Javier Palomo <javier.palomo.almena@gmail.com>

* tsdb: Remove comments referring to the sync/atomic alignment bug

Related: https://golang.org/pkg/sync/atomic/#pkg-note-BUG

Signed-off-by: Javier Palomo <javier.palomo.almena@gmail.com>
2020-07-28 10:12:42 +05:30
johncming 9801f52b0a
tsdb/chunks: fix bug of data race(#7643). (#7646)
Signed-off-by: johncming <johncming@yahoo.com>
2020-07-23 18:05:19 +05:30
Ganesh Vernekar b7c46a8c79
Merge remote-tracking branch 'upstream/master' into merge-release-2.19
Signed-off-by: Ganesh Vernekar <cs15btech11018@iith.ac.in>
2020-06-19 12:40:29 +05:30
Ganesh Vernekar 48fae12b89
Fix unsequential m-map files (#7414)
* Fix unsequential m-map files

Signed-off-by: Ganesh Vernekar <cs15btech11018@iith.ac.in>

* Fix review comments

Signed-off-by: Ganesh Vernekar <cs15btech11018@iith.ac.in>
2020-06-18 19:24:58 +05:30
Simon Pasquier 2f12049371
tsdb: improve logs when encountering corruption (#7308)
* tsdb: improve logs when encountering corruption

Signed-off-by: Simon Pasquier <spasquie@redhat.com>

* Wrap corrupted block errors

Signed-off-by: Simon Pasquier <spasquie@redhat.com>

* Add file path to head chunks

Signed-off-by: Simon Pasquier <spasquie@redhat.com>
2020-06-17 16:40:00 +02:00
Ganesh Vernekar 1627d234da
Moves the atomically accessed member to the top of the struct (#7365)
* Moves the 64bit atomically accessed field to the top of the struct.

Signed-off-by: Bryan Varner <1652015+bvarner@users.noreply.github.com>

* Moves the 64bit atomically accessed field to the top of the struct.

Signed-off-by: Bryan Varner <1652015+bvarner@users.noreply.github.com>

* Fixing up go fmt formatting issues.

Signed-off-by: Bryan Varner <1652015+bvarner@users.noreply.github.com>

Co-authored-by: Bryan Varner <1652015+bvarner@users.noreply.github.com>
2020-06-09 10:55:43 +05:30
Ganesh Vernekar a1355eb7c7
Remove time based m-map file creation (#7314)
* Remove time based m-map file creation

Signed-off-by: Ganesh Vernekar <cs15btech11018@iith.ac.in>

* Fix review comments

Signed-off-by: Ganesh Vernekar <cs15btech11018@iith.ac.in>
2020-05-29 20:08:41 +05:30
Ganesh Vernekar 83619aa9ac
Preallocate m-map file only for Windows (#7306)
Signed-off-by: Ganesh Vernekar <cs15btech11018@iith.ac.in>
2020-05-28 20:24:19 +05:30
Krasimir Georgiev 09df8d94e0
More explicit chunks and head error handling. (#7277) 2020-05-22 12:03:23 +03:00
Ganesh Vernekar d4b9fe801f
M-map full chunks of Head from disk (#6679)
When appending to the head and a chunk is full it is flushed to the disk and m-mapped (memory mapped) to free up memory

Prom startup now happens in these stages
 - Iterate the m-maped chunks from disk and keep a map of series reference to its slice of mmapped chunks.
- Iterate the WAL as usual. Whenever we create a new series, look for it's mmapped chunks in the map created before and add it to that series.

If a head chunk is corrupted the currpted one and all chunks after that are deleted and the data after the corruption is recovered from the existing WAL which means that a corruption in m-mapped files results in NO data loss.

[Mmaped chunks format](https://github.com/prometheus/prometheus/blob/master/tsdb/docs/format/head_chunks.md)  - main difference is that the chunk for mmaping now also includes series reference because there is no index for mapping series to chunks.
[The block chunks](https://github.com/prometheus/prometheus/blob/master/tsdb/docs/format/chunks.md) are accessed from the index which includes the offsets for the chunks in the chunks file - example - chunks of series ID have offsets 200, 500 etc in the chunk files.
In case of mmaped chunks, the offsets are stored in memory and accessed from that. During WAL replay, these offsets are restored by iterating all m-mapped chunks as stated above by matching the series id present in the chunk header and offset of that chunk in that file.

**Prombench results**

_WAL Replay_

1h Wal reply time
30% less wal reply time - 4m31 vs 3m36
2h Wal reply time
20% less wal reply time - 8m16 vs 7m

_Memory During WAL Replay_

High Churn:
10-15% less RAM -  32gb vs 28gb
20% less RAM after compaction 34gb vs 27gb
No Churn:
20-30% less RAM -  23gb vs 18gb
40% less RAM after compaction 32.5gb vs 20gb

Screenshots are in [this comment](https://github.com/prometheus/prometheus/pull/6679#issuecomment-621678932)


Signed-off-by: Ganesh Vernekar <cs15btech11018@iith.ac.in>
2020-05-06 21:00:00 +05:30
Ganesh Vernekar e50fdbc70c
Live m-mapping of chunks on disk (#6830)
* Live m-mapping of chunks on disk

Signed-off-by: Ganesh Vernekar <cs15btech11018@iith.ac.in>

* Fix review comments

Signed-off-by: Ganesh Vernekar <cs15btech11018@iith.ac.in>

* Fix review comments Part 2

Signed-off-by: Ganesh Vernekar <cs15btech11018@iith.ac.in>

* Fix review comments Part 3

Signed-off-by: Ganesh Vernekar <cs15btech11018@iith.ac.in>

* Fix review comments Part 4

Signed-off-by: Ganesh Vernekar <cs15btech11018@iith.ac.in>

* Attempt to fix windows bug

Signed-off-by: Ganesh Vernekar <cs15btech11018@iith.ac.in>
2020-03-19 22:03:44 +05:30