prometheus

Commit Graph

Author	SHA1	Message	Date
beorn7	db16acd7fb	Never drop a still open head chunk.	9 years ago
beorn7	5e4fa96719	Merge branch 'beorn7/storage5' into beorn7/storage6	9 years ago
beorn7	d0a4477446	Merge branch 'beorn7/storage3' into beorn7/storage4 Conflicts: storage/local/preload.go storage/local/storage.go storage/local/storage_test.go	9 years ago
beorn7	55eddab25f	Merge branch 'beorn7/storage2' into beorn7/storage3	9 years ago
beorn7	161eada3ad	Make chunkIterator even leaner.	9 years ago
beorn7	beb36df4bb	De-flag preloadChunksForRange Now there is preloadChunksForRange and preloadChunksForInstant in both, the series and the storage.	9 years ago
beorn7	0ea5801e47	Handle errors caused by data corruption more gracefully This requires all the panic calls upon unexpected data to be converted into errors returned. This pollute the function signatures quite lot. Well, this is Go... The ideas behind this are the following: - panic only if it's a programming error. Data corruptions happen, and they are not programming errors. - If we detect a data corruption, we "quarantine" the series, essentially removing it from the database and putting its data into a separate directory for forensics. - Failure during writing to a series file is not considered corruption automatically. It will call setDirty, though, so that a crashrecovery upon the next restart will commence and check for that. - Series quarantining and setDirty calls are logged and counted in metrics, but are hidden from the user of the interfaces in interface.go, whith the notable exception of Append(). The reasoning is that we treat corruption by removing the corrupted series, i.e. a query for it will return no results on its next call anyway, so return no results right now. In the case of Append(), we want to tell the user that no data has been appended, though. Minor side effects: - Now consistently using filepath.* instead of path.*. - Introduced structured logging where I touched it. This makes things less consistent, but a complete change to structured logging would be out of scope for this PR.	9 years ago
beorn7	c740789ce3	Improve predict_linear Fixes https://github.com/prometheus/prometheus/issues/1401 This remove the last (and in fact bogus) use of BoundaryValues. Thus, a whole lot of unused (and arguably sub-optimal / ugly) code can be removed here, too.	9 years ago
beorn7	454ecf3f52	Rework the way ranges and instants are handled In a way, our instants were also ranges, just with the staleness delta as range length. They are no treated equally, just that in one case, the range length is set as range, in the other the staleness delta. However, there are "real" instants where start and and time of a query is the same. In those cases, we only want to return a single value (the one closest before or at the equal start and end time). If that value is the last sample in the series, odds are we have it already in the series object. In that case, there is no need to pin or load any chunks. A special singleSampleSeriesIterator is created for that. This should greatly speed up instant queries as they happen frequently for rule evaluations.	9 years ago
beorn7	b876f8e6a5	Move lastSamplePair method up to memorySeries This implies a slight change of behavior as only samples added to the respective instance of a memorySeries are returned. However, this is most likely anyway what we want. Following cases: - Server has been restarted: Given the time it takes to cleanly shutdown and start up a server, the series are now stale anyway. An improved staleness handling (still to be implemented) will be based on tracking if a given target is continuing to expose samples for a given time series. In that case, we need a full scrape cycle to decide about staleness. So again, it makes sense to consider everything stale directly after a server restart. - Series unarchived due to a read request: The series is definitely stale so we don't want to return anything anyway. - Freshly created time series or series unarchived because of a sample append: That happens because appending a sample is imminent. Before the fingerprint lock is released, the series will have received a sample, and lastSamplePair will always returned the expected value.	9 years ago
beorn7	1e13f89039	Return SamplePair istead of *SamplePair consistently Formalize ZeroSamplePair as return value for non-existing samples. Change LastSamplePairForFingerprint to return a SamplePair (and not a pointer to it), which saves allocations in a potentially extremely frequent call.	9 years ago
beorn7	0e202dacb4	Streamline series iterator creation This will fix issue #1035 and will also help to make issue #1264 less bad. The fundamental problem in the current code: In the preload phase, we quite accurately determine which chunks will be used for the query being executed. However, in the subsequent step of creating series iterators, the created iterators are referencing _all_ in-memory chunks in their series, even the un-pinned ones. In iterator creation, we copy a pointer to each in-memory chunk of a series into the iterator. While this creates a certain amount of allocation churn, the worst thing about it is that copying the chunk pointer out of the chunkDesc requires a mutex acquisition. (Remember that the iterator will also reference un-pinned chunks, so we need to acquire the mutex to protect against concurrent eviction.) The worst case happens if a series doesn't even contain any relevant samples for the query time range. We notice that during preloading but then we will still create a series iterator for it. But even for series that do contain relevant samples, the overhead is quite bad for instant queries that retrieve a single sample from each series, but still go through all the effort of series iterator creation. All of that is particularly bad if a series has many in-memory chunks. This commit addresses the problem from two sides: First, it merges preloading and iterator creation into one step, i.e. the preload call returns an iterator for exactly the preloaded chunks. Second, the required mutex acquisition in chunkDesc has been greatly reduced. That was enabled by a side effect of the first step, which is that the iterator is only referencing pinned chunks, so there is no risk of concurrent eviction anymore, and chunks can be accessed without mutex acquisition. To simplify the code changes for the above, the long-planned change of ValueAtTime to ValueAtOrBefore time was performed at the same time. (It should have been done first, but it kind of accidentally happened while I was in the middle of writing the series iterator changes. Sorry for that.) So far, we actively filtered the up to two values that were returned by ValueAtTime, i.e. we invested work to retrieve up to two values, and then we invested more work to throw one of them away. The SeriesIterator.BoundaryValues method can be removed once #1401 is fixed. But I really didn't want to load even more changes into this PR. Benchmarks: The BenchmarkFuzz.* benchmarks run 83% faster (i.e. about six times faster) and allocate 95% fewer bytes. The reason for that is that the benchmark reads one sample after another from the time series and creates a new series iterator for each sample read. To find out how much these improvements matter in practice, I have mirrored a beefy Prometheus server at SoundCloud that suffers from both issues #1035 and #1264. To reach steady state that would be comparable, the server needs to run for 15d. So far, it has run for 1d. The test server currently has only half as many memory time series and 60% of the memory chunks the main server has. The 90th percentile rule evaluation cycle time is ~11s on the main server and only ~3s on the test server. However, these numbers might get much closer over time. In addition to performance improvements, this commit removes about 150 LOC.	9 years ago
beorn7	ef3ab96111	Populate first and last time in the chunk descriptor earlier The First time is kind of trivial as we always know it when we create a new chunkDesc. The last time is only know when the chunk is closed, so we have to set it at that time. The change saves a lot of digging down into the chunk itself. Especially the last time is relative expensive as it involves the creation of an iterator. The first time access now doesn't require locking, which is also a nice gain.	9 years ago
Julius Volz	995d3b831d	Fix most golint warnings. This is with `golint -min_confidence=0.5`. I left several lint warnings untouched because they were either incorrect or I felt it was better not to change them at the moment.	9 years ago
Brian Brazil	fdf0d0642e	Cast value to float, as that's what the console templates expect.	9 years ago
Fabian Reinartz	1535ef1457	Replace metric.SamplePair with model.SamplePair	9 years ago
Fabian Reinartz	306e8468a0	Switch from client_golang/model to common/model	9 years ago
beorn7	699946bf32	Fix chunk desc loading. If all samples in consecutive chunks have the same timestamp, the way we used to load chunks will fail. With this change, the persist watermark is used to load the right amount of chunkDescs from disk. This bug is a possible reason for the rare storage corruption we have observed.	10 years ago
beorn7	ff08f0b6fe	storage: ensure timestamp monotonicity within series. Fixes https://github.com/prometheus/prometheus/issues/481 While doing so, clean up and fix a few other things: - Fix `go vet` warnings (@fabxc to blame ;). - Fix a racey problem with unarchiving: Whenever we unarchive a series, we essentially want to do something with it. However, until we have done something with it, it appears like a series that is ready to be archived or even purged. So e.g. it would be ignored during checkpointing. With this fix, we always load the chunkDescs upon unarchiving. This is wasteful if we only want to add a new sample to an archived time series, but the (presumably more common) case where we access an archived time series in a query doesn't become more expensive. - The change above streamlined the getOrCreateSeries ond newMemorySeries flow. Also, the modTime is now always set correctly. - Fix the leveldb-backed implementation of KeyValueStore.Delete. It had the wrong behavior of still returning true, nil if a non-existing key has been passed in.	10 years ago
beorn7	3b9c421a69	Weed out all the [Gg]et* method names. The only exception is getNumChunksToPersist to avoid naming the struct member numChunksToPersist in a weird way.	10 years ago
beorn7	81b190bf45	Remove locking from series iterator. Cache chunk iterators.	10 years ago
beorn7	cd5574bf8a	Make chunk and series iterators more efficient.	10 years ago
beorn7	2235cec175	Handle fingerprint collisions.	10 years ago
beorn7	9820e5fe99	Use FastFingerprint where appropriate.	10 years ago
beorn7	11bd9ce1bd	Increase resilience of the storage against data corruption - step 3. Step 3: Remember the mtime of series files and make use of it to detect series files that are not the one the checkpoint thinks they are.	10 years ago
beorn7	1d8fc7d56f	Change minor things after code review.	10 years ago
beorn7	0056eaeb4f	Redesign series maintenance and chunk persistence.	10 years ago
beorn7	5bea942d8e	Improve various things around chunk encoding. A number of mostly minor things: - Rename chunk type -> chunk encoding. - After all, do not carry around the chunk encoding to all parts of the system, but just have one place where the encoding for new chunks is set based on the flag. The new approach has caveats as well, but the polution of so many method signatures is worse. - Use the default chunk encoding for new chunks of existing series. (Previously, only new _series_ would get chunks with the default encoding.) - Use an enum for chunk encoding. (But keep the version number for the flag, for reasons discussed previously.) - Add encoding() to the chunk interface (so that a chunk knows its own encoding - no need to have that in a different top-level function). - Got rid of newFollowUpChunk (which would keep the existing encoding for all chunks of a time series). Now only use newChunk(), which will create a chunk encoding according to the flag. - Simplified transcodeAndAdd. - Reordered methods of deltaEncodedChunk and doubleDeltaEncoded chunk to match the order in the chunk interface. - Only transcode if the chunk is not yet half full. If more than half full, add a new chunk instead.	10 years ago
beorn7	13fcf1ddbc	Implement double-delta encoded chunks.	10 years ago
beorn7	edd716e63c	Fix the embarrassing bug introduced in commit `0851945`. In that commit, the 'maintainSeries' call was accidentally removed. This commit refactors things a bit so that there is now a clean 'maintainMemorySeries' and a 'maintainArchivedSeries' call. Straighten the nomenclature a bit (consistently use 'drop' for chunks and 'purge' for series/metrics). Remove the annoying 'Completed maintenance sweep through archived fingerprints' message if there were no archived fingerprints to do maintenance on.	10 years ago
beorn7	5d3cd65a5d	Improve performance of ingestion. - Parallelize AppendSamples as much as possible without breaking the contract about temporal order. - Allocate more fingerprint locker slots. - Do not run early checkpoints if we are behind on chunk persistence. - Increase fpMinWaitDuration to give the disk more time for more important things. Also, switch math.MaxInt64 and math.MinInt64 to the new constants.	10 years ago
Bjoern Rabenstein	5859b74f1b	Clean up license issues. - Move CONTRIBUTORS.md to the more common AUTHORS. - Added the required NOTICE file. - Changed "Prometheus Team" to "The Prometheus Authors". - Reverted the erroneous changes to the Apache License.	10 years ago
Bjoern Rabenstein	622e8350cd	Fix a bug handling freshly unarchived series. Usually, if you unarchive a series, it is to add something to it, which will create a new head chunk. However, if a series in unarchived, and before anything is added to it, it is handled by the maintenance loop, it will be archived again. In that case, we have to load the chunkDescs to know the lastTime of the series to be archived. Usually, this case will happen only rarely (as a race, has never happened so far, possibly because the locking around unarchiving and the subsequent sample append is smart enough). However, during crash recovery, we sometimes treat series as "freshly unarchived" without directly appending a sample. We might add more cases of that type later, so better deal with archiving properly and load chunkDescs if required.	10 years ago
Bjoern Rabenstein	fee88a7a77	Remove the remaining races, new and old. Also, resolve a few other TODOs. Change-Id: Icb39b5a5e8ca22ebcb48771cd8951c5d9e112691	10 years ago
Bjoern Rabenstein	674624f1c8	Completed more TODOs. - Documented checkpoint file format. - High-level description of series sanitation. - Replace fp.LoadFromString panic with an error. (Change in client_golang already submitted.) - Introduced checks for series file size where appropriate. - Removed two Law of Demeter violations. Change-Id: I555d97a2c8f4769820c2fc8bf5d6f4e160222abc	10 years ago
Bjoern Rabenstein	7d11019aa2	Squash a few trivial TODOs. - Delete unneeded file view_adapter.go. - Assessed that we still need the fingerprints in nodes (to create iterators). - Turned numMemChunkDescs into a metric. Change-Id: I29be963c795a075ec00c095f76bf26405535609d	10 years ago
Bjoern Rabenstein	bb42cc2e2d	Evict based on memory pressure. Evict recently used chunks last. Change-Id: Ie6168f0cdb3917bdc63b6fe15585dd70c1e42afe	10 years ago
Bjoern Rabenstein	904acd43da	Add crash recovery. Fix the behavior if preload for non-existent series is requested. Instead of returning an error (which triggers a panic further up), simply count those incidents. They can happen regularly, we just want to know if they happen too frequently because that would mean the indexing is behind or broken. Change-Id: I4b2d1b93c4146eeea897d188063cb9574a270f8b	10 years ago
Bjoern Rabenstein	5f8e9617ef	Add more tests. Add an end-to-end fuzz and race test. Fix a race exposed by the above. Change-Id: Ifaa39a90cefbde8d4c29bda197cc92592ded21bb	10 years ago
Bjoern Rabenstein	d215e013b7	Fix the weird chunkDesc shuffling bug. The root cause was that after chunkDesc eviction, the offset between memory representation of chunk layout (via chunkDescs in memory) was shiftet against chunks as layed out on disk. Keeping the offset up to date is by no means trivial, so this commit is pretty involved. Also, found a race that for some reason didn't bite us so far: Persisting chunks was completel unlocked, so if chunks were purged on disk at the same time, disaster would strike. However, locking the persisting of chunk revealed interesting dead locks. Basically, never queue under the fp lock. Change-Id: I1ea9e4e71024cabbc1f9601b28e74db0c5c55db8	10 years ago
Bjoern Rabenstein	a617269b12	Avoid unnecessary cloning of the head chunk. Change-Id: I5da774515d5493166a197b5814d0a720628cfaff	10 years ago
Bjoern Rabenstein	74c9b34a5e	Improve storage instrumentation even more. Add gauge for chunks and chunkdescs in memory (backed by a global variable to be used later not only for instrumentation but also for memory management). Refactored instrumentation code once more (instrumentation.go is back :). Change-Id: Ife39947e22a48cac4982db7369c231947f446e17	10 years ago
Bjoern Rabenstein	443dd33805	Improve instrumentation in storage. Also, fix some other minor bugs. Change-Id: If72f1c058b0f47d3e378fdf80228d7e9a8db06c7	10 years ago
Bjoern Rabenstein	192bf52c41	Evict chunkDescs, too. Change-Id: I8b70f22fbf1dfcbc49f9ec391985144649e6ce9c	10 years ago
Bjoern Rabenstein	096fa0f8b2	Squash a number of TODOs. - Staleness delta is no a proper function parameter and not replicated from package ast. - Named type 'chunks' replaced by explicit '[]chunk' to avoid confusion. - For the same reason, replaced 'chunkDescs' by '[]*chunkDescs'. - Verified that math.Modf is not a speed enhancement over conversion (actually 5x slower). - Renamed firstTimeField, lastTimeField into chunkFirstTime and chunkLastTime. - Verified unpin() is sufficiently goroutine-safe. - Decided not to update archivedFingerprintToTimeRange upon series truncation and added a rationale why. Change-Id: I863b8d785e5ad9f71eb63e229845eacf1bed8534	10 years ago
Bjoern Rabenstein	427c8d53a5	Fix handling of empty chunkDescs while preloading chunks. Change-Id: I73ce89fe0ef90c6eda78218e5be2cbfa0207c364	10 years ago
Bjoern Rabenstein	ecee5d8281	Fix head chunk persisting and a chunkDesc race condition. - Head chunk persisting only happens in evictOlderThan, so do it there. (With the previous code, it would never happen.) - Raw accesses to chunkDesc.chunk are now done via isEvicted (with locking). Change-Id: I48b07b56dfea4899b50df159b4ea566954396fcd	10 years ago
Bjoern Rabenstein	2b4ff620aa	Return a nop iterator for series that have been purged completely. Change-Id: I6e92cac4472486feefdecba8593c17867e8c710d	10 years ago
Bjoern Rabenstein	6e3a366f91	Only archive a time series when none of its chunks is pinned. Change-Id: I7e4b67c34b417b8980173bc5dc3b213bd7d698e5	10 years ago
Bjoern Rabenstein	ca42a22e20	Add safety panic to seriesMap.put. Change-Id: I4d4d2e45cc0f908a33eb1ae6e3ee6796adfcbd1e	10 years ago

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68 Commits (8ec10ae7a5c3ec7a0b6e54c326a09d9afc9d39e8)