prometheus

Commit Graph

Author	SHA1	Message	Date
Fabian Reinartz	cc6f988a5e	storage: fix Querier interface documentation	9 years ago
Julius Volz	3bfec97d46	Make the storage interface higher-level. See discussion in https://groups.google.com/forum/#!topic/prometheus-developers/bkuGbVlvQ9g The main idea is that the user of a storage shouldn't have to deal with fingerprints anymore, and should not need to do an individual preload call for each metric. The storage interface needs to be made more high-level to not expose these details. This also makes it easier to reuse the same storage interface for remote storages later, as fewer roundtrips are required and the fingerprint concept doesn't work well across the network. NOTE: this deliberately gets rid of a small optimization in the old query Analyzer, where we dedupe instants and ranges for the same series. This should have a minor impact, as most queries do not have multiple selectors loading the same series (and at the same offset).	10 years ago
beorn7	fc6737b7fb	storage: improve index lookups tl;dr: This is not a fundamental solution to the indexing problem (like tindex is) but it at least avoids utilizing the intersection problem to the greatest possible amount. In more detail: Imagine the following query: nicely:aggregating:rule{job="foo",env="prod"} While it uses a nicely aggregating recording rule (which might have a very low cardinality), Prometheus still intersects the low number of fingerprints for `{__name__="nicely:aggregating:rule"}` with the many thousands of fingerprints matching `{job="foo"}` and with the millions of fingerprints matching `{env="prod"}`. This totally innocuous query is dead slow if the Prometheus server has a lot of time series with the `{env="prod"}` label. Ironically, if you make the query more complicated, it becomes blazingly fast: nicely:aggregating:rule{job=~"foo",env=~"prod"} Why so? Because Prometheus only intersects with non-Equal matchers if there are no Equal matchers. That's good in this case because it retrieves the few fingerprints for `{__name__="nicely:aggregating:rule"}` and then starts right ahead to retrieve the metric for those FPs and checking individually if they match the other matchers. This change is generalizing the idea of when to stop intersecting FPs and go into "retrieve metrics and check them individually against remaining matchers" mode: - First, sort all matchers by "expected cardinality". Matchers matching the empty string are always worst (and never used for intersections). Equal matchers are in general consider best, but by using some crude heuristics, we declare some better than others (instance labels or anything that looks like a recording rule). - Then go through the matchers until we hit a threshold of remaining FPs in the intersection. This threshold is higher if we are already in the non-Equal matcher area as intersection is even more expensive here. - Once the threshold has been reached (or we have run out of matchers that do not match the empty string), start with "retrieve metrics and check them individually against remaining matchers". A beefy server at SoundCloud was spending 67% of its CPU time in index lookups (fingerprintsForLabelPairs), serving mostly a dashboard that is exclusively built with recording rules. With this change, it spends only 35% in fingerprintsForLabelPairs. The CPU usage dropped from 26 cores to 18 cores. The median latency for query_range dropped from 14s to 50ms(!). As expected, higher percentile latency didn't improve that much because the new approach is _occasionally_ running into the worst case while the old one was _systematically_ doing so. The 99th percentile latency is now about as high as the median before (14s) while it was almost twice as high before (26s).	10 years ago
Julius Volz	b7b6717438	Separate query interface out of local.Storage. PromQL only requires a much narrower interface than local.Storage in order to run queries. Narrower interfaces are easier to replace and test, too. We could also change the web interface to use local.Querier, except that we'll probably use appending functions from there in the future.	10 years ago
beorn7	836f1db04c	Improve MetricsForLabelMatchers WIP: This needs more tests. It now gets a from and through value, which it may opportunistically use to optimize the retrieval. With possible future range indices, this could be used in a very efficient way. This change merely applies some easy checks, which should nevertheless solve the use case of heavy rule evaluations on servers with a lot of series churn. Idea is the following: - Only archive series that are at least as old as the headChunkTimeout (which was already extremely unlikely to happen). - Then maintain a high watermark for the last archival, i.e. no archived series has a sample more recent than that watermark. - Any query that doesn't reach to a time before that watermark doesn't have to touch the archive index at all. (A production server at Soundcloud with the aforementioned series churn and heavy rule evaluations spends 50% of its CPU time in archive index lookups. Since rule evaluations usually only touch very recent values, most of those lookup should disappear with this change.) - Federation with a very broad label matcher will profit from this, too. As a byproduct, the un-needed MetricForFingerprint method was removed from the Storage interface.	10 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.	10 years ago
beorn7	2581648f70	Separate iterators by offset Add test that exposes the problem.	10 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.	10 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.	10 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.	10 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.	10 years ago
Fabian Reinartz	59f1e722df	Return error on sample appending	10 years ago
beorn7	ec08c9a391	Rework the way to communicate backpressure (AKA suspended ingestion) This gives up on the idea to communicate throuh the Append() call (by either not returning as it is now or returning an error as suggested/explored elsewhere). Here I have added a Throttled() call, which has the advantage that it can be called before a whole _batch_ of Append()'s. Scrapes will happen completely or not at all. Same for rule group evaluations. That's a highly desired behavior (as discussed elsewhere). The code is even simpler now as the whole ingestion buffer could be removed. Logging of throttled mode has been streamlined and will create at most one message per minute.	10 years ago
beorn7	3f4d22e4c7	Update doc comment This should have gone into a previous commit, but I forgot to save this particular file.	10 years ago
Fabian Reinartz	e061595352	Move COWMetric into storage/metric package	10 years ago
Fabian Reinartz	1535ef1457	Replace metric.SamplePair with model.SamplePair	10 years ago
Fabian Reinartz	438e232c9b	Fix grouping of import blocks	10 years ago
Fabian Reinartz	306e8468a0	Switch from client_golang/model to common/model	10 years ago
beorn7	8c196c1028	Minor doc fixes.	11 years ago
Fabian Reinartz	6bfb4549a6	storage: add LastSamplePairForFingerprint method	11 years ago
Fabian Reinartz	5b91ea9b36	storage: improve label matching and allow unset matching. Matching of empty labels now also matches metrics where the label was not explicitly set to the empty string.	11 years ago
Fabian Reinartz	5c6c0e2faa	Add storage method to delete time series	11 years ago
Fabian Reinartz	aff01e29c3	Limit retrievable samples to retention window. The storage does not delete data immediately after the retention period. We don't want to retrieve this data as it causes artifacts.	11 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.	11 years ago
beorn7	81b190bf45	Remove locking from series iterator. Cache chunk iterators.	11 years ago
Fabian Reinartz	d8440d75f1	Do not start storage processing before Start() is called.	11 years ago
beorn7	be11cb2b07	Remove the sample ingestion channel. The one central sample ingestion channel has caused a variety of trouble. This commit removes it. Targets and rule evaluation call an Append method directly now. To incorporate multiple storage backends (like OpenTSDB), storage.Tee forks the Append into two different appenders. Note that the tsdb queue manager had its own queue anyway. It was a queue after a queue... Much queue, so overhead... Targets have their own little buffer (implemented as a channel) to avoid stalling during an http scrape. But a new scrape will only be started once the old one is fully ingested. The contraption of three pipelined ingesters was removed. A Target is an ingester itself now. Despite more logic in Target, things should be less confusing now. Also, remove lint and vet warnings in ast.go.	11 years ago
beorn7	fe518fdb28	Simplify AppendSamples by allowing it to be goroutine-unsafe.	11 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.	11 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.	11 years ago
Julius Volz	a6bc42bc61	Minor formatting/spelling fixups.	11 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.	11 years ago
Julius Volz	c9618d11e8	Introduce copy-on-write for metrics in AST. This depends on changes in: https://github.com/prometheus/client_golang/tree/cow-metrics. Change-Id: I80b94833a60ddf954c7cd92fd2cfbebd8dd46142	11 years ago
Bjoern Rabenstein	14bda4180c	Changes after pair code review. Change-Id: Ib72d40f8e9027818cfbbd32a7a7201eebda07455	11 years ago
Bjoern Rabenstein	f1de5b0c4e	Run checkpointing of in-memory metrics and head chunks periodically. Checkpointing interval is now a command line flag. Along the way, several things were refactored. - Restructure the way the storage is started and stopped.. - Number of series in checkpoint is now a uint64, not a varint. (Breaks old checkpoints, needs wipe!) - More consistent naming and order of methods. Change-Id: I883d9170c9a608ee716bb0ab3d0ded8ca03760d9	11 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	11 years ago
Bjoern Rabenstein	443dd33805	Improve instrumentation in storage. Also, fix some other minor bugs. Change-Id: If72f1c058b0f47d3e378fdf80228d7e9a8db06c7	11 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	11 years ago
Bjoern Rabenstein	b3ed9aa7a2	Clean up start-up and shut-down. Change-Id: Idff4bbb0a15a9f879bfbb3da5b1025179cab5e2c	11 years ago
Bjoern Rabenstein	38fc24d0ed	Fix targetpool_test.go and other tests. Change-Id: I91a4dd1d39e01f174e1aaae653ce1ed7aecaa624	11 years ago
Bjoern Rabenstein	8fba3302bc	Bold changes to concurrency. (WIP. Probably doesn't work yet.) Change-Id: Id1537dfcca53831a1d428078a5863ece7bdf4875	11 years ago
Bjoern Rabenstein	fcdf5a8ee7	Fix bugs in chunk evict code. Also, simplify code by re-looking up metric in metric map. Change-Id: Ib2092f9184374e5a543e87d3a9f4a74fda64b193	11 years ago
Bjoern Rabenstein	7e6a03fbf9	Fix a few concurrency issues before starting to use the new fp locker. Change-Id: I8615e8816e79ef0882e123163ee590c739b79d12	11 years ago
Bjoern Rabenstein	e9ff29c547	Comment/code cleanup. Change-Id: I38736e3d0fec79759a2bafa35aecf914480ff810	11 years ago
Bjoern Rabenstein	0031a448e2	Add WaitForIndexing. Change-Id: I5a5c975c4246632f937413322c855bbe63d00802	11 years ago
Bjoern Rabenstein	c7aad110fb	Add an indexing queue and batch the ops. Some other improvements on the way, in particular codec -> codable renaming and addition of LookupSet methods. Change-Id: I978f8f3f84ca8e4d39a9d9f152ae0ad274bbf4e2	11 years ago
Bjoern Rabenstein	71206dbc06	More code cleanups. Add license text everywhere. And others.... Change-Id: I11ccde267a2ef7eb366c4788ba7aeae14ba7545c	11 years ago
Julius Volz	630b5a087a	Also consider on-disk fingerprints during purge. This reintroduces LevelDB iterators so that we can iterate through all the on-disk fingerprints. Change-Id: I007ee4638d038d2a4461bbda27f30fcaad411474	11 years ago
Bjoern Rabenstein	f5f9f3514a	Major code cleanup. - Make it go-vet and golint clean. - Add comments, TODOs, etc. Change-Id: If1392d96f3d5b4cdde597b10c8dff1769fcfabe2	11 years ago
Bjoern Rabenstein	bbf49200ab	Implement methods in persistence.go. Change-Id: I804cdd0b30420e171825fd86fe1281eca0d5e638	11 years ago

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57 Commits (cc6f988a5ecffa263d58ccce4029a6988dcd5f6f)