We convert longs to ints using `Math.toIntExact` in places where we're
sure there will be no overflow, but this doesn't explain the intent of
these conversions very well. This commit introduces a dedicated method
for these conversions, and adds an assertion that we never overflow.
If a searchable snapshot shard fails (e.g. its node leaves the cluster)
we want to be able to start it up again on a different node as quickly
as possible to avoid unnecessarily blocking or failing searches. It
isn't feasible to fully restore such shards in an acceptably short time.
In particular we would like to be able to deal with the `can_match`
phase of a search ASAP so that we can skip unnecessary waiting on shards
that may still be warming up but which are not required for the search.
This commit solves this problem by introducing a system index that holds
much of the data required to start a shard. Today(*) this means it holds
the contents of every file with size <8kB, and the first 4kB of every
other file in the shard. This system index acts as a second-level cache,
behind the first-level node-local disk cache but in front of the blob
store itself. Reading chunks from the index is slower than reading them
directly from disk, but faster than reading them from the blob store,
and is also replicated and accessible to all nodes in the cluster.
(*) the exact heuristics for what we should put into the system index
are still under investigation and may change in future.
This second-level cache is populated when we attempt to read a chunk
which is missing from both levels of cache and must therefore be read
from the blob store.
We also introduce `SearchableSnapshotsBlobStoreCacheIntegTests` which
verify that we do not hit the blob store more than necessary when
starting up a shard that we've seen before, whether due to a node
restart or because a snapshot was mounted multiple times.
Backport of #60522
Co-authored-by: Tanguy Leroux <tlrx.dev@gmail.com>
The test didn't take into account the case where 0 documents are
indexed into the shard, meaning that files aren't loaded during
the pre-warm phase. The test injects FileSystem failures, if
the snapshot doesn't contain any files, pre-warm doesn't read
any files and the recovery completes normally.
Closes#61295
Backport of #61317
Fixes a test failure in which we allocated some shards and then
relocated them elsewhere, invalidating an assertion about the recovery
statistics which assumed that the shards stayed where they were
originally allocated.
Closes#61067.
This pull request adds recovery state tracking for Searchable Snapshots.
In order to track recoveries for searchable snapshot backed indices, this pull
request adds a new type of RecoveryState.
This newRecoveryState instance is able to deal with the
small differences that arise during Searchable snapshots recoveries.
Those differences can be summarized as follows:
- The Directory implementation that's provided by SearchableSnapshots mark the
snapshot files as reused during recovery. In order to keep track of the
recovery process as the cache is pre-warmed, those files shouldn't be marked
as reused.
- Once the shard is created, the cache starts its pre-warming phase, meaning that
we should keep track of those downloads during that process and tie the recovery
to this pre-warming phase. The shard is considered recovered once this pre-warming
phase has finished.
Backport of #60505
Implements license degradation behavior for searchable snapshots. Snapshot-backed shards are failed when the license becomes invalid, and shards won't be reallocated. After valid license is put in place again, shards are allocated again.
* Merge test runner task into RestIntegTest (#60261)
* Merge test runner task into RestIntegTest
* Reorganizing Standalone runner and RestIntegTest task
* Rework general test task configuration and extension
* Fix merge issues
* use former 7.x common test configuration
This commit does three things:
* Removes all Copyright/license headers for the build.gradle files under x-pack. (implicit Apache license)
* Removes evaluationDependsOn(xpackModule('core')) from build.gradle files under x-pack
* Removes a place holder test in favor of disabling the test task (in the async plugin)
Closing a regular index and mounting a snapshot-backed index into that existing index does not clean the existing index
folders of those preexisting shards.
This PR removes the existing Lucene / translog files once the searchable snapshot shard is starting up. Future PRs will
make reuse of the existing index files to populate the cache.
- Replace immediate task creations by using task avoidance api
- One step closer to #56610
- Still many tasks are created during configuration phase. Tackled in separate steps
Due to complicated access checks (reads and writes execute in their own access context) on some repositories (GCS, Azure, HDFS), using a hard coded buffer size of 4k for restores was needlessly inefficient.
By the same token, the use of stream copying with the default 8k buffer size for blob writes was inefficient as well.
We also had dedicated, undocumented buffer size settings for HDFS and FS repositories. For these two we would use a 100k buffer by default. We did not have such a setting for e.g. GCS though, which would only use an 8k read buffer which is needlessly small for reading from a raw `URLConnection`.
This commit adds an undocumented setting that sets the default buffer size to `128k` for all repositories. It removes wasteful allocation of such a large buffer for small writes and reads in case of HDFS and FS repositories (i.e. still using the smaller buffer to write metadata) but uses a large buffer for doing restores and uploading segment blobs.
This should speed up Azure and GCS restores and snapshots in a non-trivial way as well as save some memory when reading small blobs on FS and HFDS repositories.
Today when mounting a searchable snapshot we obtain the snapshot/index
UUIDs and then assume that these are the UUIDs used during the
subsequent restore. If you concurrently delete the snapshot and replace
it with one with the same name then this assumption is violated, with
chaotic consequences.
This commit introduces a check that ensures that the snapshot UUID does
not change during the mount process. If the snapshot remains in place
then the index UUID necessarily does not change either.
Relates #50999
Since #58728 writing operations on searchable snapshot directory cache files
are executed in an asynchronous manner using a dedicated thread pool. The
thread pool used is searchable_snapshots which has been created to execute
prewarming tasks.
Reusing the same thread pool wasn't a good idea as it can lead to deadlock
situations. One of these situation arose in a test failure where the thread pool
was full of prewarming tasks, all waiting for a cache file to be accessible, while
the cache file was being evicted by the cache service. But such an eviction
can only be processed when all read/write operations on the cache file are
completed and in this case the deadlock occurred because the cache file was
actively being read by a concurrent search which also won the privilege to
write the range of bytes in cache... and this writing operation could never have
been completed because of the prewarming tasks making no progress and
filling up the thread pool.
This commit renames the searchable_snapshots thread pool to
searchable_snapshots_cache_fetch_async. Assertions are added to assert
that cache writes are executed using this thread pool and to assert that read
on cached index inputs are executed using a different thread pool to avoid
potential deadlock situations.
This commit also adds a searchable_snapshots_cache_prewarming that is
used to execute prewarming tasks. It also converts the existing cache prewarming
test into a more complte integration test that creates multiple searchable
snapshot indices concurrently with randomized thread pool sizes, and verifies
that all files have been correctly prewarmed.
Today we empty the searchable snapshots cache when cleanly closing a
shard, but leak cache files in some cases involving an unclean shutdown.
Such leaks are not permanent, they are cleaned up on shard relocation or
deletion, but they still might last for arbitrarily long until that
happens. This commit introduces a cleanup process that runs during node
startup to catch such leaks sooner.
Also, today we permit searchable snapshots to be held on custom data
paths, and store the corresponding cache files within the custom
location. Supporting this feature would make the cleanup process
significantly more complicated since it would require each node to parse
the index metadata for the shards it held before shutdown. Yet, this
feature is undocumented and offers minimal benefits to searchable
snapshots. Therefore with this commit we forbid custom data paths for
searchable snapshot shards.
In order to ensure that we do not write a broken piece of `RepositoryData`
because the phyiscal repository generation was moved ahead more than one step
by erroneous concurrent writing to a repository we must check whether or not
the current assumed repository generation exists in the repository physically.
Without this check we run the risk of writing on top of stale cached repository data.
Relates #56911
* Enforce higher priority for RepositoriesService ClusterStateApplier
This avoids shards allocation failures when the repository instance
comes in the same ClusterState update as the shard allocation.
Backport of #58808
This commit creates a new Gradle plugin to provide a separate task name
and source set for running YAML based REST tests. The only project
converted to use the new plugin in this PR is distribution/archives/integ-test-zip.
For which the testing has been moved to :rest-api-spec since it makes the most
sense and it avoids a small but awkward change to the distribution plugin.
The remaining cases in modules, plugins, and x-pack will be handled in followups.
This plugin is distinctly different from the plugin introduced in #55896 since
the YAML REST tests are intended to be black box tests over HTTP. As such they
should not (by default) have access to the classpath for that which they are testing.
The YAML based REST tests will be moved to separate source sets (yamlRestTest).
The which source is the target for the test resources is dependent on if this
new plugin is applied. If it is not applied, it will default to the test source
set.
Further, this introduces a breaking change for plugin developers that
use the YAML testing framework. They will now need to either use the new source set
and matching task, or configure the rest resources to use the old "test" source set that
matches the old integTest task. (The former should be preferred).
As part of this change (which is also breaking for plugin developers) the
rest resources plugin has been removed from the build plugin and now requires
either explicit application or application via the new YAML REST test plugin.
Plugin developers should be able to fix the breaking changes to the YAML tests
by adding apply plugin: 'elasticsearch.yaml-rest-test' and moving the YAML tests
under a yamlRestTest folder (instead of test)
Despite all my attempts I did not manage to reproduce issues like the ones
described in #58961. My guess is that the _mount request got retried at
some point but I wasn't able to validate this assumption.
Still, the FsSearchableSnapshotsIT can be pretty disk heavy if a small
random chunk size and a large number of documents is picked up in the
tests. The parent class also does not verify the acknowledged status
of some requests.
This commit lowers down the chunk size and number of docs in tests
(this is extensively tests in unit tests) and also adds assertions on
acknowledged responses.
Relates #58961
Since #58728 part of searchable snapshot shard files are written in cache
in an asynchronous manner in a dedicated thread pool. It means that even
if a search query is successful and returns, there are still more bytes to
write in the cached files on disk.
On CI this can be slow; if we want to check that the cached_bytes_written
has changed we need to check multiple times to give some time for the
cached data to be effectively written.
This commit changes CacheFile and CachedBlobContainerIndexInput so that
the read operations made by these classes are now progressively executed
and do not wait for full range to be written in cache. It relies on the change
introduced in #58477 and it is the last change extracted from #58164.
Relates #58164
Restoring from a snapshot (which is a particular form of recovery) does not currently take recovery throttling into account
(i.e. the `indices.recovery.max_bytes_per_sec` setting). While restores are subject to their own throttling (repository
setting `max_restore_bytes_per_sec`), this repository setting does not allow for values to be configured differently on a
per-node basis. As restores are very similar in nature to peer recoveries (streaming bytes to the node), it makes sense to
configure throttling in a single place.
The `max_restore_bytes_per_sec` setting is also changed to default to unlimited now, whereas previously it was set to
`40mb`, which is the current default of `indices.recovery.max_bytes_per_sec`). This means that no behavioral change
will be observed by clusters where the recovery and restore settings were not adapted.
Relates https://github.com/elastic/elasticsearch/issues/57023
Co-authored-by: James Rodewig <james.rodewig@elastic.co>
* Replace compile configuration usage with api (#58451)
- Use java-library instead of plugin to allow api configuration usage
- Remove explicit references to runtime configurations in dependency declarations
- Make test runtime classpath input for testing convention
- required as java library will by default not have build jar file
- jar file is now explicit input of the task and gradle will ensure its properly build
* Fix compile usages in 7.x branch
This commit adds the BuildParams.testSeed to the repository base paths used
in searchable snapshots QA tests. For S3 and GCS the test seed is added for
coherency sake with other integration tests while it's required for Azure as
Azure 3rd party tests are executed on CI simultaneously for regular and
SAS token accounts.
Closes#58260
SparseFileTracker.Gap can keep a reference to the corresponding range it is about to fill,
it does not need to resolve the range each time onSuccess/onProgress/onFailure are
called.
Relates #58477
Today SparseFileTracker allows to wait for a range to become available
before executing a given listener. In the case of searchable snapshot,
we'd like to be able to wait for a large range to be filled (ie, downloaded
and written to disk) while being able to execute the listener as soon as
a smaller range is available.
This pull request is an extract from #58164 which introduces a
ProgressListenableActionFuture that is used internally by
SparseFileTracker. The progressive listenable future allows to register
listeners attached to SparseFileTracker.Gap so that they are executed
once the Gap is completed (with success or failure) or as soon as the
Gap progress reaches a given progress value. This progress value is
defined when the tracker.waitForRange() method is called; this method
has been modified to accept a range and another listener's range to
operate on.
Co-authored-by: Elastic Machine <elasticmachine@users.noreply.github.com>
Today the read/write locks used internally by CacheFile object are
wrapped into a ReleasableLock. This is not strictly required and also
prevents usage of the tryLock() methods which we would like to use
for early releasing of read operations (#58164).
Today a mounted searchable snapshot defaults to having the same replica
configuration as the index that was snapshotted. This commit changes this
behaviour so that we default to zero replicas on these indices, but allow the
user to override this in the mount request.
Relates #50999
* Remove usage of deprecated testCompile configuration
* Replace testCompile usage by testImplementation
* Make testImplementation non transitive by default (as we did for testCompile)
* Update CONTRIBUTING about using testImplementation for test dependencies
* Fail on testCompile configuration usage
Today you can convert a searchable snapshot index back into a regular index by
restoring the underlying snapshot, but this is somewhat wasteful if the shards
are already in cache since it copies the whole index from the repository again.
Instead, we can make use of the locally-cached data by using the clone API to
copy the contents of the cache into the layout expected by a regular shard.
This commit marks the searchable snapshot's private index settings as
`NotCopyableOnResize` so that they are removed by resize operations such as
cloning.
Cloning a regular index typically hard-links the underlying files rather than
copying them, but this is tricky to support in the case of a searchable
snapshot so this commit takes the simpler approach of always copying the
underlying files.
While investigating possible optimizations to speed up searchable
snapshots shard restores, we noticed that Elasticsearch builds the
list of shard files on local disk in order to compare it with the list of
files contained in the snapshot to restore. This list of files is
materialized with a MetadataSnapshot object whose construction
involves to read the footer checksum of every files of the shard
using Store.checksumFromLuceneFile() method.
Further investigation shows that a MetadataSnapshot object is
also created for other types of operations like building the list of
files to recover in a peer recovery (and primary shard relocation)
or in order to assign a shard to a node. These operations use the
Store.getMetadata(IndexCommit) method to build the list of files
and checksums.
In the case of searchable snapshots building the MetadataSnapshot
object can potentially trigger cache misses, which in turn can
cause the download and the writing in cache of the last range of
the file in order to check the 16 bytes footer. This in turn can
cause more evictions.
Since searchable snapshots already contains the footer information
of every file in BlobStoreIndexShardSnapshot it can directly read the
checksum from it and avoid to use the cache at all to create a
MetadataSnapshot for the operations mentioned above.
This commit adds a shortcut to the
SearchableSnapshotDirectory.openInput() method - similarly to what
already exists for segment infos - so that it creates a specific
IndexInput for checksum reading operation.
This test sometimes fails when prewarming is enabled because
it's possible that some files are cached in background while the
test tries to clear the cache. This commit disables prewarming
for this test.
A FilterBlobContainer class was introduced in #55952 and it delegates
its behavior to a given BlobContainer while allowing to override
only necessary methods.
This commit replaces the existing BlobContainerWrapper class from
the test framework with the new FilterBlobContainer from core.
This commit changes searchable snapshots so that it now respects the
repository's max_restore_bytes_per_sec setting when it downloads blobs.
Backport of #55952 for 7.x
David Turner
Francisco Fernández Castaño
Yannick Welsch
Rene Groeschke
Jake Landis
Armin Braun
Tanguy Leroux
Daniel Mitterdorfer
David Kyle
Mark Vieira
Lee Hinman
Ignacio Vera
Julie Tibshirani