* Make the tasks run with only a single directory
There was a change that tried to get indexing to run on multiple disks
It made a bunch of changes to how tasks run, effectively hiding the
"safe" directory for tasks to write files into from the task code itself
making it extremely difficult to do anything correctly inside of a task.
This change reverts those changes inside of the tasks and makes it so that
only the task runners are the ones that make decisions about which
mount points should be used for storing task-related files.
It adds the config druid.worker.baseTaskDirs which can be used by the
task runners to know which directories they should schedule tasks inside of.
The TaskConfig remains the authoritative source of configuration for where
and how an individual task should be operating.
### Description
This change allows for input sources used during MSQ ingestion to be authorized for multiple input source types, instead of just 1. Such an input source that allows for multiple types is the CombiningInputSource.
Also fixed bug that caused some input source specific functions to be authorized against the permissions
`
[
new ResourceAction(new Resource(ResourceType.EXTERNAL, ResourceType.EXTERNAL), Action.READ),
new ResourceAction(new Resource(ResourceType.EXTERNAL, {input_source_type}), Action.READ)
]
`
when the inputSource based authorization feature is enabled, when it should instead be authorized against
`
[
new ResourceAction(new Resource(ResourceType.EXTERNAL, {input_source_type}), Action.READ)
]
`
Fixes#13837.
### Description
This change allows for input source type security in the native task layer.
To enable this feature, the user must set the following property to true:
`druid.auth.enableInputSourceSecurity=true`
The default value for this property is false, which will continue the existing functionality of needing authorization to write to the respective datasource.
When this config is enabled, the users will be required to be authorized for the following resource action, in addition to write permission on the respective datasource.
`new ResourceAction(new Resource(ResourceType.EXTERNAL, {INPUT_SOURCE_TYPE}, Action.READ`
where `{INPUT_SOURCE_TYPE}` is the type of the input source being used;, http, inline, s3, etc..
Only tasks that provide a non-default implementation of the `getInputSourceResources` method can be submitted when config `druid.auth.enableInputSourceSecurity=true` is set. Otherwise, a 400 error will be thrown.
changes:
* introduce ColumnFormat to separate physical storage format from logical type. ColumnFormat is now used instead of ColumnCapabilities to get column handlers for segment creation
* introduce new 'auto' type indexer and merger which produces a new common nested format of columns, which is the next logical iteration of the nested column stuff. Essentially this is an automatic type column indexer that produces the most appropriate column for the given inputs, making either STRING, ARRAY<STRING>, LONG, ARRAY<LONG>, DOUBLE, ARRAY<DOUBLE>, or COMPLEX<json>.
* revert NestedDataColumnIndexer, NestedDataColumnMerger, NestedDataColumnSerializer to their version pre #13803 behavior (v4) for backwards compatibility
* fix a bug in RoaringBitmapSerdeFactory if anything actually ever wrote out an empty bitmap using toBytes and then later tried to read it (the nerve!)
Due to race conditions, the BrokerServerView may sometimes try to add a segment to a server which has already been removed from the inventory. This results in an NPE and keeps the BrokerServerView from processing all change requests.
This change introduces the concept of input source type security model, proposed in #13837.. With this change, this feature is only available at the SQL layer, but we will expand to native layer in a follow up PR.
To enable this feature, the user must set the following property to true:
druid.auth.enableInputSourceSecurity=true
The default value for this property is false, which will continue the existing functionality of having the usage all external sources being authorized against the hardcoded resource action
new ResourceAction(new Resource(ResourceType.EXTERNAL, ResourceType.EXTERNAL), Action.READ
When this config is enabled, the users will be required to be authorized for the following resource action
new ResourceAction(new Resource(ResourceType.EXTERNAL, {INPUT_SOURCE_TYPE}, Action.READ
where {INPUT_SOURCE_TYPE} is the type of the input source being used;, http, inline, s3, etc..
Documentation has not been added for the feature as it is not complete at the moment, as we still need to enable this for the native layer in a follow up pr.
* Add segment generator counters to reports
* Remove unneeded annotation
* Fix checkstyle and coverage
* Add persist and merged as new metrics
* Address review comments
* Fix checkstyle
* Create metrics class to handle updating counters
* Address review comments
* Add rowsPushed as a new metrics
changes:
* fixes inconsistent handling of byte[] values between ExprEval.bestEffortOf and ExprEval.ofType, which could cause byte[] values to end up as java toString values instead of base64 encoded strings in ingest time transforms
* improved ExpressionTransform binding to re-use ExprEval.bestEffortOf when evaluating a binding instead of throwing it away
* improved ExpressionTransform array handling, added RowFunction.evalDimension that returns List<String> to back Row.getDimension and remove the automatic coercing of array types that would typically happen to expression transforms unless using Row.getDimension
* added some tests for ExpressionTransform with array inputs
* improved ExpressionPostAggregator to use partial type information from decoration
* migrate some test uses of InputBindings.forMap to use other methods
Changes:
- Set `useRoundRobinSegmentAssignment` in coordinator dynamic config to `true` by default.
- Set `batchSegmentAllocation` in `TaskLockConfig` (used in Overlord runtime properties) to `true` by default.
* Lower default maxRowsInMemory for realtime ingestion.
The thinking here is that for best ingestion throughput, we want
intermediate persists to be as big as possible without using up all
available memory. So, we rely mainly on maxBytesInMemory. The default
maxRowsInMemory (1 million) is really just a safety: in case we have
a large number of very small rows, we don't want to get overwhelmed
by per-row overheads.
However, maximum ingestion throughput isn't necessarily the primary
goal for realtime ingestion. Query performance is also important. And
because query performance is not as good on the in-memory dataset, it's
helpful to keep it from growing too large. 150k seems like a reasonable
balance here. It means that for a typical 5 million row segment, we
won't trigger more than 33 persists due to this limit, which is a
reasonable number of persists.
* Update tests.
* Update server/src/main/java/org/apache/druid/segment/indexing/RealtimeTuningConfig.java
Co-authored-by: Kashif Faraz <kashif.faraz@gmail.com>
* Fix test.
* Fix link.
---------
Co-authored-by: Kashif Faraz <kashif.faraz@gmail.com>
* This makes the zookeeper connection retry count configurable. This is presently hardcoded to 29 tries which ends up taking a long time for the druid node to shutdown in case of ZK connectivity loss.
Having a shorter retry count helps k8s deployments to fail fast. In situations where the underlying k8s node loses network connectivity or is no longer able to talk to zookeeper, failing fast can trigger pod restarts which can then reassign the pod to a healthy k8s node.
Existing behavior is preserved, but users can override this property if needed.
* Improve memory efficiency of WrappedRoaringBitmap.
Two changes:
1) Use an int[] for sizes 4 or below.
2) Remove the boolean compressRunOnSerialization. Doesn't save much
space, but it does save a little, and it isn't adding a ton of value
to have it be configurable. It was originally configurable in case
anything broke when enabling it, but it's been a while and nothing
has broken.
* Slight adjustment.
* Adjust for inspection.
* Updates.
* Update snaps.
* Update test.
* Adjust test.
* Fix snaps.
The FiniteFirehoseFactory and InputRowParser classes were deprecated in 0.17.0 (#8823) in favor of InputSource & InputFormat. This PR removes the FiniteFirehoseFactory and all its implementations along with classes solely used by them like Fetcher (Used by PrefetchableTextFilesFirehoseFactory). Refactors classes including tests using FiniteFirehoseFactory to use InputSource instead.
Removing InputRowParser may not be as trivial as many classes that aren't deprecated depends on it (with no alternatives), like EventReceiverFirehoseFactory. Hence FirehoseFactory, EventReceiverFirehoseFactory, and Firehose are marked deprecated.
* Make CompactionSearchPolicy injectable
A small refactoring that makes the search policy for compaction injectable.
Future changes can introduce new search policies that can be configured and
injected so that operators can choose which search policy is best suited for
their cluster.
This will also allow us to de-couple the scheduling of compaction jobs from
the CompactSegments duty, allowing the co-ordinator to schedule compaction
jobs faster than the duty lifecycle.
This PR is made so that it easy to review the future changes.
* fix tests
When both plainText and TLS ports are set in druid, the redirection to a different leader node can fail. This is caused by how we compare a redirect path and the leader locations registered with a druid node. While the registered location has both plainText and TLS port set, the redirect path only has one port since it's a URI.
* merge druid-core, extendedset, and druid-hll into druid-processing to simplify everything
* fix poms and license stuff
* mockito is evil
* allow reset of JvmUtils RuntimeInfo if tests used static injection to override
* Use an HllSketchHolder object to enable optimized merge
HllSketchAggregatorFactory.combine had been implemented using a
pure pair-wise, "make a union -> add 2 things to union -> get sketch"
algorithm. This algorithm does 2 things that was CPU
1) The Union object always builds an HLL_8 sketch regardless of the
target type. This means that when the target type is not HLL_8, we
spent CPU cycles converting to HLL_8 and back over and over again
2) By throwing away the Union object and converting back to the
HllSketch only to build another Union object, we do lots and lots
of copy+conversions of the HllSketch
This change introduces an HllSketchHolder object which can hold onto
a Union object and delay conversion back into an HllSketch until
it is actually needed. This follows the same pattern as the
SketchHolder object for theta sketches.
* Fallback virtual column
This virtual columns enables falling back to another column if
the original column doesn't exist. This is useful when doing
column migrations and you have some old data with column X,
new data with column Y and you want to use Y if it exists, X
otherwise so that you can run a consistent query against all of
the data.
Add a new API to return the history of changes to automatic compaction config history to make it easy for users to see what changes have been made to their auto-compaction config.
The API is scoped per dataSource to allow users to triage issues with an individual dataSource. The API responds with a list of configs when there is a change to either the settings that impact all auto-compaction configs on a cluster or the dataSource in question.
* discover nested columns when using nested column indexer for schemaless
* move useNestedColumnIndexerForSchemaDiscovery from AppendableIndexSpec to DimensionsSpec
Much improved table functions
* Revises properties, definitions in the catalog
* Adds a "table function" abstraction to model such functions
* Specific functions for HTTP, inline, local and S3.
* Extended SQL types in the catalog
* Restructure external table definitions to use table functions
* EXTEND syntax for Druid's extern table function
* Support for array-valued table function parameters
* Support for array-valued SQL query parameters
* Much new documentation
* Kinesis: More robust default fetch settings.
1) Default recordsPerFetch and recordBufferSize based on available memory
rather than using hardcoded numbers. For this, we need an estimate
of record size. Use 10 KB for regular records and 1 MB for aggregated
records. With 1 GB heaps, 2 processors per task, and nonaggregated
records, recordBufferSize comes out to the same as the old
default (10000), and recordsPerFetch comes out slightly lower (1250
instead of 4000).
2) Default maxRecordsPerPoll based on whether records are aggregated
or not (100 if not aggregated, 1 if aggregated). Prior default was 100.
3) Default fetchThreads based on processors divided by task count on
Indexers, rather than overall processor count.
4) Additionally clean up the serialized JSON a bit by adding various
JsonInclude annotations.
* Updates for tests.
* Additional important verify.
* single typed "root" only nested columns now mimic "regular" columns of those types
* incremental index can now use nested column indexer instead of string indexer for discovered columns
* Validate response headers and fix exception logging
A class of QueryException were throwing away their
causes making it really hard to determine what's
going wrong when something goes wrong in the SQL
planner specifically. Fix that and adjust tests
to do more validation of response headers as well.
We allow 404s and 307s to be returned even without
authorization validated, but others get converted to 403
* Unify the handling of HTTP between SQL and Native
The SqlResource and QueryResource have been
using independent logic for things like error
handling and response context stuff. This
became abundantly clear and painful during a
change I was making for Window Functions, so
I unified them into using the same code for
walking the response and serializing it.
Things are still not perfectly unified (it would
be the absolute best if the SqlResource just
took SQL, planned it and then delegated the
query run entirely to the QueryResource), but
this refactor doesn't take that fully on.
The new code leverages async query processing
from our jetty container, the different
interaction model with the Resource means that
a lot of tests had to be adjusted to align with
the async query model. The semantics of the
tests remain the same with one exception: the
SqlResource used to not log requests that failed
authorization checks, now it does.
This commit adds a new class `InputStats` to track the total bytes processed by a task.
The field `processedBytes` is published in task reports along with other row stats.
Major changes:
- Add class `InputStats` to track processed bytes
- Add method `InputSourceReader.read(InputStats)` to read input rows while counting bytes.
> Since we need to count the bytes, we could not just have a wrapper around `InputSourceReader` or `InputEntityReader` (the way `CountableInputSourceReader` does) because the `InputSourceReader` only deals with `InputRow`s and the byte information is already lost.
- Classic batch: Use the new `InputSourceReader.read(inputStats)` in `AbstractBatchIndexTask`
- Streaming: Increment `processedBytes` in `StreamChunkParser`. This does not use the new `InputSourceReader.read(inputStats)` method.
- Extend `InputStats` with `RowIngestionMeters` so that bytes can be exposed in task reports
Other changes:
- Update tests to verify the value of `processedBytes`
- Rename `MutableRowIngestionMeters` to `SimpleRowIngestionMeters` and remove duplicate class
- Replace `CacheTestSegmentCacheManager` with `NoopSegmentCacheManager`
- Refactor `KafkaIndexTaskTest` and `KinesisIndexTaskTest`
Refactor DataSource to have a getAnalysis method()
This removes various parts of the code where while loops and instanceof
checks were being used to walk through the structure of DataSource objects
in order to build a DataSourceAnalysis. Instead we just ask the DataSource
for its analysis and allow the stack to rebuild whatever structure existed.
* Zero-copy local deep storage.
This is useful for local deep storage, since it reduces disk usage and
makes Historicals able to load segments instantaneously.
Two changes:
1) Introduce "druid.storage.zip" parameter for local storage, which defaults
to false. This changes default behavior from writing an index.zip to writing
a regular directory. This is safe to do even during a rolling update, because
the older code actually already handled unzipped directories being present
on local deep storage.
2) In LocalDataSegmentPuller and LocalDataSegmentPusher, use hard links
instead of copies when possible. (Generally this is possible when the
source and destination directory are on the same filesystem.)
* Druid automated quickstart
* remove conf/druid/single-server/quickstart/_common/historical/jvm.config
* Minor changes in python script
* Add lower bound memory for some services
* Additional runtime properties for services
* Update supervise script to accept command arguments, corresponding changes in druid-quickstart.py
* File end newline
* Limit the ability to start multiple instances of a service, documentation changes
* simplify script arguments
* restore changes in medium profile
* run-druid refactor
* compute and pass middle manager runtime properties to run-druid
supervise script changes to process java opts array
use argparse, leave free memory, logging
* Remove extra quotes from mm task javaopts array
* Update logic to compute minimum memory
* simplify run-druid
* remove debug options from run-druid
* resolve the config_path provided
* comment out service specific runtime properties which are computed in the code
* simplify run-druid
* clean up docs, naming changes
* Throw ValueError exception on illegal state
* update docs
* rename args, compute_only -> compute, run_zk -> zk
* update help documentation
* update help documentation
* move task memory computation into separate method
* Add validation checks
* remove print
* Add validations
* remove start-druid bash script, rename start-druid-main
* Include tasks in lower bound memory calculation
* Fix test
* 256m instead of 256g
* caffeine cache uses 5% of heap
* ensure min task count is 2, task count is monotonic
* update configs and documentation for runtime props in conf/druid/single-server/quickstart
* Update docs
* Specify memory argument for each profile in single-server.md
* Update middleManager runtime.properties
* Move quickstart configs to conf/druid/base, add bash launch script, support python2
* Update supervise script
* rename base config directory to auto
* rename python script, changes to pass repeated args to supervise
* remove exmaples/conf/druid/base dir
* add docs
* restore changes in conf dir
* update start-druid-auto
* remove hashref for commands in supervise script
* start-druid-main java_opts array is comma separated
* update entry point script name in python script
* Update help docs
* documentation changes
* docs changes
* update docs
* add support for running indexer
* update supported services list
* update help
* Update python.md
* remove dir
* update .spelling
* Remove dependency on psutil and pathlib
* update docs
* Update get_physical_memory method
* Update help docs
* update docs
* update method to get physical memory on python
* udpate spelling
* update .spelling
* minor change
* Minor change
* memory comptuation for indexer
* update start-druid
* Update python.md
* Update single-server.md
* Update python.md
* run python3 --version to check if python is installed
* Update supervise script
* start-druid: echo message if python not found
* update anchor text
* minor change
* Update condition in supervise script
* JVM not jvm in docs
* Processors for Window Processing
This is an initial take on how to use Processors
for Window Processing. A Processor is an interface
that transforms RowsAndColumns objects.
RowsAndColumns objects are essentially combinations
of rows and columns.
The intention is that these Processors are the start
of a set of operators that more closely resemble what
DB engineers would be accustomed to seeing.
* Wire up windowed processors with a query type that
can run them end-to-end. This code can be used to
actually run a query, so yay!
* Wire up windowed processors with a query type that
can run them end-to-end. This code can be used to
actually run a query, so yay!
* Some SQL tests for window functions. Added wikipedia
data to the indexes available to the
SQL queries and tests validating the windowing
functionality as it exists now.
Co-authored-by: Gian Merlino <gianmerlino@gmail.com>
* Switching emitter. This will allow for a per feed emitter designation.
This will work by looking at an event's feed and direct it to a specific emitter. If no specific feed is specified for a feed.
The emitter can direct the event to a default emitter.
* fix checkstyle issues and make docs for switching emitter use basic event feeds
* fix broken docs, add test, and guard against misconfigurations
* add module test
add switching emitter module test
* fix broken SwitchingEmitterModuleTest
* add apache license to top of test
* fix checkstyle issues
* address comments by adding javadocs, removing a todo, and making druid docs more clear
In a cluster with a large number of streaming tasks (~1000), SegmentAllocateActions
on the overlord can often take very long intervals of time to finish thus causing spikes
in the `task/action/run/time`. This may result in lag building up while a task waits for a
segment to get allocated.
The root causes are:
- large number of metadata calls made to the segments and pending segments tables
- `giant` lock held in `TaskLockbox.tryLock()` to acquire task locks and allocate segments
Since the contention typically arises when several tasks of the same datasource try
to allocate segments for the same interval/granularity, the allocation run times can be
improved by batching the requests together.
Changes
- Add flags
- `druid.indexer.tasklock.batchSegmentAllocation` (default `false`)
- `druid.indexer.tasklock.batchAllocationMaxWaitTime` (in millis) (default `1000`)
- Add methods `canPerformAsync` and `performAsync` to `TaskAction`
- Submit each allocate action to a `SegmentAllocationQueue`, and add to correct batch
- Process batch after `batchAllocationMaxWaitTime`
- Acquire `giant` lock just once per batch in `TaskLockbox`
- Reduce metadata calls by batching statements together and updating query filters
- Except for batching, retain the whole behaviour (order of steps, retries, etc.)
- Respond to leadership changes and fail items in queue when not leader
- Emit batch and request level metrics
SQL test framework extensions
* Capture planner artifacts: logical plan, etc.
* Planner test builder validates the logical plan
* Validation for the SQL resut schema (we already have
validation for the Druid row signature)
* Better Guice integration: properties, reuse Guice modules
* Avoid need for hand-coded expr, macro tables
* Retire some of the test-specific query component creation
* Fix query log hook race condition
Detects self-redirects, redirect loops, long redirect chains, and redirects to unknown servers.
Treat all of these cases as an unavailable service, retrying if the retry policy allows it.
Previously, some of these cases would lead to a prompt, unretryable error. This caused
clients contacting an Overlord during a leader change to fail with error messages like:
org.apache.druid.rpc.RpcException: Service [overlord] redirected too many times
Additionally, a slight refactor of callbacks in ServiceClientImpl improves readability of
the flow through onSuccess.
The batch segment sampling performs significantly better than the older method
of sampling if there are a large number of used segments. It also avoids duplicates.
Changes:
- Make batch segment sampling the default
- Deprecate the property `useBatchedSegmentSampler`
- Remove unused coordinator config `druid.coordinator.loadqueuepeon.repeatDelay`
- Cleanup `KillUnusedSegments`
- Simplify `KillUnusedSegmentsTest`, add better tests, remove redundant tests
Main changes:
1) Convert SeekableStreamIndexTaskClient to an interface, move old code
to SeekableStreamIndexTaskClientSyncImpl, and add new implementation
SeekableStreamIndexTaskClientAsyncImpl that uses ServiceClient.
2) Add "chatAsync" parameter to seekable stream supervisors that causes
the supervisor to use an async task client.
3) In SeekableStreamSupervisor.discoverTasks, adjust logic to avoid making
blocking RPC calls in workerExec threads.
4) In SeekableStreamSupervisor generally, switch from Futures.successfulAsList
to FutureUtils.coalesce, so we can better capture the errors that occurred
with contacting individual tasks.
Other, related changes:
1) Add ServiceRetryPolicy.retryNotAvailable, which controls whether
ServiceClient retries unavailable services. Useful since we do not
want to retry calls unavailable tasks within the service client. (The
supervisor does its own higher-level retries.)
2) Add FutureUtils.transformAsync, a more lambda friendly version of
Futures.transform(f, AsyncFunction).
3) Add FutureUtils.coalesce. Similar to Futures.successfulAsList, but
returns Either instead of using null on error.
4) Add JacksonUtils.readValue overloads for JavaType and TypeReference.
Segment assignments can take very long due to the strategy cost computation
for a large number of segments. This commit allows segment assignments to be
done in a round-robin fashion within a tier. Only segment balancing takes cost-based
decisions to move segments around.
Changes
- Add dynamic config `useRoundRobinSegmentAssignment` with default value false
- Add `RoundRobinServerSelector`. This does not implement the `BalancerStrategy`
as it does not conform to that contract and may also be used in conjunction with a
strategy (round-robin for `RunRules` and a cost strategy for `BalanceSegments`)
- Drops are still cost-based even when round-robin assignment is enabled.
Druid catalog basics
Catalog object model for tables, columns
Druid metadata DB storage (as an extension)
REST API to update the catalog (as an extension)
Integration tests
Model only: no planner integration yet
`cachingCost` strategy has some discrepancies when compared to cost strategy.
This commit addresses two of these by retaining the same behaviour as the `cost` strategy
when computing the cost of moving a segment to a server:
- subtract the self cost of a segment if it is being served by the target server
- subtract the cost of segments that are marked to be dropped
Other changes:
- Add tests to verify fixed strategy. These tests would fail without the fixes made to `CachingCostStrategy.computeCost()`
- Fix the definition of the segment related metrics in the docs.
- Fix some docs issues introduced in #13181
* Support for middle manager less druid, tasks launch as k8s jobs
* Fixing forking task runner test
* Test cleanup, dependency cleanup, intellij inspections cleanup
* Changes per PR review
Add configuration option to disable http/https proxy for the k8s client
Update the docs to provide more detail about sidecar support
* Removing un-needed log lines
* Small changes per PR review
* Upon task completion we callback to the overlord to update the status / locaiton, for slower k8s clusters, this reduces locking time significantly
* Merge conflict fix
* Fixing tests and docs
* update tiny-cluster.yaml
changed `enableTaskLevelLogPush` to `encapsulatedTask`
* Apply suggestions from code review
Co-authored-by: Abhishek Agarwal <1477457+abhishekagarwal87@users.noreply.github.com>
* Minor changes per PR request
* Cleanup, adding test to AbstractTask
* Add comment in peon.sh
* Bumping code coverage
* More tests to make code coverage happy
* Doh a duplicate dependnecy
* Integration test setup is weird for k8s, will do this in a different PR
* Reverting back all integration test changes, will do in anotbher PR
* use StringUtils.base64 instead of Base64
* Jdk is nasty, if i compress in jdk 11 in jdk 17 the decompressed result is different
Co-authored-by: Rahul Gidwani <r_gidwani@apple.com>
Co-authored-by: Abhishek Agarwal <1477457+abhishekagarwal87@users.noreply.github.com>
In clusters with a large number of segments, the duty `MarkAsUnusedOvershadowedSegments`
can take a long very long time to finish. This is because of the costly invocation of
`timeline.isOvershadowed` which is done for every used segment in every coordinator run.
Changes
- Use `DataSourceSnapshot.getOvershadowedSegments` to get all overshadowed segments
- Iterate over this set instead of all used segments to identify segments that can be marked as unused
- Mark segments as unused in the DB in batches rather than one at a time
- Refactor: Add class `SegmentTimeline` for ease of use and readability while using a
`VersionedIntervalTimeline` of segments.
* First set of changes for framework
* Second set of changes to move segment map function to data source
* Minot change to server manager
* Removing the createSegmentMapFunction from JoinableFactoryWrapper and moving to JoinDataSource
* Checkstyle fixes
* Patching Eric's fix for injection
* Checkstyle and fixing some CI issues
* Fixing code inspections and some failed tests and one injector for test in avatica
* Another set of changes for CI...almost there
* Equals and hashcode part update
* Fixing injector from Eric + refactoring for broadcastJoinHelper
* Updating second injector. Might revert later if better way found
* Fixing guice issue in JoinableFactory
* Addressing review comments part 1
* Temp changes refactoring
* Revert "Temp changes refactoring"
This reverts commit 9da42a9ef0.
* temp
* Temp discussions
* Refactoring temp
* Refatoring the query rewrite to refer to a datasource
* Refactoring getCacheKey by moving it inside data source
* Nullable annotation check in injector
* Addressing some comments, removing 2 analysis.isJoin() checks and correcting the benchmark files
* Minor changes for refactoring
* Addressing reviews part 1
* Refactoring part 2 with new test cases for broadcast join
* Set for nullables
* removing instance of checks
* Storing nullables in guice to avoid checking on reruns
* Fixing a test case and removing an irrelevant line
* Addressing the atomic reference review comments
* Remove basePersistDirectory from tuning configs.
Since the removal of CliRealtime, it serves no purpose, since it is
always overridden in production using withBasePersistDirectory given
some subdirectory of the task work directory.
Removing this from the tuning config has a benefit beyond removing
no-longer-needed logic: it also avoids the side effect of empty
"druid-realtime-persist" directories getting created in the systemwide
temp directory.
* Test adjustments to appropriately set basePersistDirectory.
* Remove unused import.
* Fix RATC constructor.
* Refactor Calcite test "framework" for planner tests
Refactors the current Calcite tests to make it a bit easier
to adjust the set of runtime objects used within a test.
* Move data creation out of CalciteTests into TestDataBuilder
* Move "framework" creation out of CalciteTests into
a QueryFramework
* Move injector-dependent functions from CalciteTests
into QueryFrameworkUtils
* Wrapper around the planner factory, etc. to allow
customization.
* Bulk of the "framework" created once per class rather
than once per test.
* Refactor tests to use a test builder
* Change all testQuery() methods to use the test builder.
Move test execution & verification into a test runner.
We introduce two new configuration keys that refine the query context security model controlled by druid.auth.authorizeQueryContextParams. When that value is set to true then two other configuration options become available:
druid.auth.unsecuredContextKeys: The set of query context keys that do not require a security check. Use this for the "white-list" of key to allow. All other keys go through the existing context key security checks.
druid.auth.securedContextKeys: The set of query context keys that do require a security check. Use this when you want to allow all but a specific set of keys: only these keys go through the existing context key security checks.
Both are set using JSON list format:
druid.auth.securedContextKeys=["secretKey1", "secretKey2"]
You generally set one or the other values. If both are set, unsecuredContextKeys acts as exceptions to securedContextKeys.
In addition, Druid defines two query context keys which always bypass checks because Druid uses them internally:
sqlQueryId
sqlStringifyArrays
1) Better support for Java 9+ in RuntimeInfo. This means that in many cases,
an actual validation can be done.
2) Clearer log message in cases where an actual validation cannot be done.
Druid currently uses Zookeeper dependent options as the default.
This commit updates the following to use HTTP as the default instead.
- task runner. `druid.indexer.runner.type=remote -> httpRemote`
- load queue peon. `druid.coordinator.loadqueuepeon.type=curator -> http`
- server inventory view. `druid.serverview.type=curator -> http`
Fixes#12822
The framework added here make it easy to write tests that verify the behaviour and interactions
of the following entities under various conditions:
- `DruidCoordinator`
- `HttpLoadQueuePeon`, `LoadQueueTaskMaster`
- coordinator duties: `BalanceSegments`, `RunRules`, `UnloadUnusedSegments`, etc.
- datasource retention rules: `LoadRule`, `DropRule`
Changes:
Add the following main classes:
- `CoordinatorSimulation` and related interfaces to dictate behaviour of simulation
- `CoordinatorSimulationBuilder` to build a simulation.
- `BlockingExecutorService` to keep submitted tasks in queue and execute them
only when explicitly invoked.
Add tests:
- `CoordinatorSimulationBaseTest`, `SegmentLoadingTest`, `SegmentBalancingTest`
- `SegmentLoadingNegativeTest` to contain tests which assert the existing erroneous behaviour
of segment loading. Once the behaviour is fixed, these tests will be moved to the regular
`SegmentLoadingTest`.
Please refer to the README.md in `org.apache.druid.server.coordinator.simulate` for more details
* Converted Druid planner to use statement handlers
Converts the large collection of if-statements for statement
types into a set of classes: one per supported statement type.
Cleans up a few error messages.
* Revisions from review comments
* Build fix
* Build fix
* Resolve merge confict.
* More merges with QueryResponse PR
* More parameterized type cleanup
Forces a rebuild due to a flaky test
* Allocate numCorePartitions using only used segments
* Add corePartition checks in existing test
* Separate committedMaxId and overallMaxId
* Fix bug: replace overall with committed
This commit fixes issues with delayed supervisor termination during certain transient states.
Tasks can be created during supervisor termination and left behind since the cleanup may
not consider these newly added tasks.
#12178 added a lock for the entire process of task creation to prevent such dangling tasks.
But it also introduced a deadlock scenario as follows:
- An invocation of `runInternal` is in progress.
- A `stop` request comes, acquires `stateChangeLock` and submit a `ShutdownNotice`
- `runInternal` keeps waiting to acquire the `stateChangeLock`
- `ShutdownNotice` remains stuck in the notice queue because `runInternal` is still running
- After some timeout, the supervisor goes through a forced termination
Fix:
* `SeekableStreamSupervisor.runInternal` - do not try to acquire lock if supervisor is already stopping
* `SupervisorStateManager.maybeSetState` - do not allow transitions from STOPPING state
* Move web-console dependency from druid-server to distribution
* Add a test to check if the web-console is correctly integrated
* exclude web-console from 'other integration tests'
* Revert "exclude web-console from 'other integration tests'"
This reverts commit 8d72225544.
* Revert "Add a test to check if the web-console is correctly integrated"
This reverts commit d6ac8f3087.
* Expose HTTP Response headers from SqlResource
This change makes the SqlResource expose HTTP response
headers in the same way that the QueryResource exposes them.
Fundamentally, the change is to pipe the QueryResponse
object all the way through to the Resource so that it can
populate response headers. There is also some code
cleanup around DI, as there was a superfluous FactoryFactory
class muddying things up.
* fix bug in /status/properties filtering
* Refactor tests to use jackson for parsing druid.server.hiddenProperties instead of hacky string modifications
* make javadoc more descriptive using example
* add in a sanity assertion that raw properties keyset size is greater than filtered properties keyset size
* Add interpolation to JsonConfigurator
* Fix checkstyle
* Fix tests by removing common-text override
* Add back commons-text without version
* Remove unused hadoopDir configs
* Move some stuff to hopefully pass coverage
* more consistent expression error messages
* review stuff
* add NamedFunction for Function, ApplyFunction, and ExprMacro to share common stuff
* fixes
* add expression transform name to transformer failure, better parse_json error messaging
* apache#12063 Ease of hidding sensitive properties from /status/properties endpoint
* apache#12063 Ease of hidding sensitive properties from /status/properties endpoint
* apache#12063 Ease of hidding sensitive properties from /status/properties endpoint
using one property for hiding properties, updated the index.md to document hiddenProperties
* apache#12063 Ease of hidding sensitive properties from /status/properties endpoint
Added java docs
* apache#12063 Ease of hidding sensitive properties from /status/properties endpoint
Add "password", "key", "token", "pwd" as default druid.server.hiddenProperties
fixed typo and removed redundant space
Co-authored-by: zemin <zemin.piao@adyen.com>
* json_value adjustments
changes:
* native json_value expression now has optional 3rd argument to specify type, which will cast all values to the specified type
* rework how JSON_VALUE is wired up in SQL. Now we are using a custom convertlet to translate JSON_VALUE(... RETURNING type) into dedicated JSON_VALUE_BIGINT, JSON_VALUE_DOUBLE, JSON_VALUE_VARCHAR, JSON_VALUE_ANY instead of using the calcite StandardConvertletTable that wraps JSON_VALUE_ANY in a CAST, so that we preserve the typing of JSON_VALUE to pass down to the native expression as the 3rd argument
* fix json_value_any to be usable by humans too, coverage
* fix bug
* checkstyle
* checkstyle
* review stuff
* validate that options to json_value are the supported options rather than ignore them
* remove more legacy undocumented functions
This commit is a first draft of the revised integration test framework which provides:
- A new directory, integration-tests-ex that holds the new integration test structure. (For now, the existing integration-tests is left unchanged.)
- Maven module druid-it-tools to hold code placed into the Docker image.
- Maven module druid-it-image to build the Druid-only test image from the tarball produced in distribution. (Dependencies live in their "official" image.)
- Maven module druid-it-cases that holds the revised tests and the framework itself. The framework includes file-based test configuration, test-specific clients, test initialization and updated versions of some of the common test support classes.
The integration test setup is primarily a huge mass of details. This approach refactors many of those details: from how the image is built and configured to how the Docker Compose scripts are structured to test configuration. An extensive set of "readme" files explains those details. Rather than repeat that material here, please consult those files for explanations.
Fixes KafkaEmitter not emitting queryType for a native query. The Event to JSON serialization was extracted to the external class: EventToJsonSerializer. This was done to simplify the testing logic for the serialization as well as extract the responsibility of serialization to the separate class.
The logic builds ObjectNode incrementally based on the event .toMap method. Parsing each entry individually ensures that the Jackson polymorphic annotations are respected. Not respecting these annotation caused the missing of the queryType from output event.
* Refactor SqlLifecycle into statement classes
Create direct & prepared statements
Remove redundant exceptions from tests
Tidy up Calcite query tests
Make PlannerConfig more testable
* Build fixes
* Added builder to SqlQueryPlus
* Moved Calcites system properties to saffron.properties
* Build fix
* Resolve merge conflict
* Fix IntelliJ inspection issue
* Revisions from reviews
Backed out a revision to Calcite tests that didn't work out as planned
* Build fix
* Fixed spelling errors
* Fixed failed test
Prepare now enforces security; before it did not.
* Rebase and fix IntelliJ inspections issue
* Clean up exception handling
* Fix handling of JDBC auth errors
* Build fix
* More tweaks to security messages
This is used to control access to the EXTERN function, which allows
reading external data in SQL. The EXTERN function is not usable in
production as of today, but it is used by the task-based SQL engine
contemplated in #12262.
In the current druid code base, we have the interface DataSegmentPusher which allows us to push segments to the appropriate deep storage without the extension being worried about the semantics of how to push too deep storage.
While working on #12262, whose some part of the code will go as an extension, I realized that we do not have an interface that allows us to do basic "write, get, delete, deleteAll" operations on the appropriate deep storage without let's say pulling the s3-storage-extension dependency in the custom extension.
Hence, the idea of StorageConnector was born where the storage connector sits inside the druid core so all extensions have access to it.
Each deep storage implementation, for eg s3, GCS, will implement this interface.
Now with some Jackson magic, we bind the implementation of the correct deep storage implementation on runtime using a type variable.
* Add check for eternity time segment to SqlSegmentsMetadataQuery
* Add check for half eternities
* Add multiple segments test
* Add failing test to document known issue
* Refactor Guice initialization
Builders for various module collections
Revise the extensions loader
Injector builders for server startup
Move Hadoop init to indexer
Clean up server node role filtering
Calcite test injector builder
* Revisions from review comments
* Build fixes
* Revisions from review comments
* Improved Java 17 support and Java runtime docs.
1) Add a "Java runtime" doc page with information about supported
Java versions, garbage collection, and strong encapsulation..
2) Update asm and equalsverifier to versions that support Java 17.
3) Add additional "--add-opens" lines to surefire configuration, so
tests can pass successfully under Java 17.
4) Switch openjdk15 tests to openjdk17.
5) Update FrameFile to specifically mention Java runtime incompatibility
as the cause of not being able to use Memory.map.
6) Update SegmentLoadDropHandler to log an error for Errors too, not
just Exceptions. This is important because an IllegalAccessError is
encountered when the correct "--add-opens" line is not provided,
which would otherwise be silently ignored.
7) Update example configs to use druid.indexer.runner.javaOptsArray
instead of druid.indexer.runner.javaOpts. (The latter is deprecated.)
* Adjustments.
* Use run-java in more places.
* Add run-java.
* Update .gitignore.
* Exclude hadoop-client-api.
Brought in when building on Java 17.
* Swap one more usage of java.
* Fix the run-java script.
* Fix flag.
* Include link to Temurin.
* Spelling.
* Update examples/bin/run-java
Co-authored-by: Xavier Léauté <xl+github@xvrl.net>
Co-authored-by: Xavier Léauté <xl+github@xvrl.net>
* Use nonzero default value of maxQueuedBytes.
The purpose of this parameter is to prevent the Broker from running out
of memory. The prior default is unlimited; this patch changes it to a
relatively conservative 25MB.
This may be too low for larger clusters. The risk is that throughput
can decrease for queries with large resultsets or large amounts of intermediate
data. However, I think this is better than the risk of the prior default, which
is that these queries can cause the Broker to go OOM.
* Alter calculation.
Sysmonitor stats (mem, fs, disk, net, cpu, swap, sys, tcp) are reported by all Druid processes, including Peons that are ephemeral in nature. Since Peons always run on the same host as the MiddleManager that spawned them and is unlikely to change, the SyMonitor metrics emitted by Peon are merely duplicates. This is often not a problem except when machines are super-beefy. Imagine a 64-core machine and 32 workers running on this machine. now you will have each Peon reporting metrics for each core. that's an increase of (32 * 64)x in the number of metrics. This leads to a metric explosion.
This PR updates MetricsModule to check node role running while registering SysMonitor and not to load any existing SysMonitor$Stats.
Few indexing tasks register RealtimeMetricsMonitor or TaskRealtimeMetricsMonitor with the process’s MonitorScheduler when they start. These monitors never unregister themselves (they always return true, they'd need to return false to unregister). Each of these monitors emits a set of metrics once every druid.monitoring.emissionPeriod.
As a result, after executing several tasks for a while, Indexer emits metrics of these tasks even after they're long gone.
Proposed Solution
Since one should be able to obtain the last round of ingestion metrics after the task unregisters the monitor, introducing lastRoundMetricsToBePushed variable to keep track of the same and overriding the AbstractMonitor.monitor method in RealtimeMetricsMonitor, TaskRealtimeMetricsMonitor to implement the new logic.
* initial commit of bucket dimensions for metrics
return counts of segments that have rowcount in a bucket size for a datasource
return average value of rowcount per segment in a datasource
added unit test
naming could use a lot of work
buckets right now are not finalized
added javadocs
altered metrics.md
* fix checkstyle issues
* addressed review comments
add monitor test
move added functionality to new monitor
update docs
* address comments
renamed monitor
handle tombstones better
update docs
added javadocs
* Add support for tombstones in the segment distribution
* undo changes to tombstone segmentizer factory
* fix accidental whitespacing changes
* address comments regarding metrics documentation
and rename variable to be more accurate
* fix tests
* fix checkstyle issues
* fix broken test
* undo removal of timeout
* Mid-level service client and updated high-level clients.
Our servers talk to each other over HTTP. We have a low-level HTTP
client (HttpClient) that is super-asynchronous and super-customizable
through its handlers. It's also proven to be quite robust: we use it
for Broker -> Historical communication over the wide variety of query
types and workloads we support.
But the low-level client has no facilities for service location or
retries, which means we have a variety of high-level clients that
implement these in their own ways. Some high-level clients do a better
job than others. This patch adds a mid-level ServiceClient that makes
it easier for high-level clients to be built correctly and harmoniously,
and migrates some of the high-level logic to use ServiceClients.
Main changes:
1) Add ServiceClient org.apache.druid.rpc package. That package also
contains supporting stuff like ServiceLocator and RetryPolicy
interfaces, and a DiscoveryServiceLocator based on
DruidNodeDiscoveryProvider.
2) Add high-level OverlordClient in org.apache.druid.rpc.indexing.
3) Indexing task client creator in TaskServiceClients. It uses
SpecificTaskServiceLocator to find the tasks. This improves on
ClientInfoTaskProvider by caching task locations for up to 30 seconds
across calls, reducing load on the Overlord.
4) Rework ParallelIndexSupervisorTaskClient to use a ServiceClient
instead of extending IndexTaskClient.
5) Rework RemoteTaskActionClient to use a ServiceClient instead of
DruidLeaderClient.
6) Rework LocalIntermediaryDataManager, TaskMonitor, and
ParallelIndexSupervisorTask. As a result, MiddleManager, Peon, and
Overlord no longer need IndexingServiceClient (which internally used
DruidLeaderClient).
There are some concrete benefits over the prior logic, namely:
- DruidLeaderClient does retries in its "go" method, but only retries
exactly 5 times, does not sleep between retries, and does not retry
retryable HTTP codes like 502, 503, 504. (It only retries IOExceptions.)
ServiceClient handles retries in a more reasonable way.
- DruidLeaderClient's methods are all synchronous, whereas ServiceClient
methods are asynchronous. This is used in one place so far: the
SpecificTaskServiceLocator, so we don't need to block a thread trying
to locate a task. It can be used in other places in the future.
- HttpIndexingServiceClient does not properly handle all server errors.
In some cases, it tries to parse a server error as a successful
response (for example: in getTaskStatus).
- IndexTaskClient currently makes an Overlord call on every task-to-task
HTTP request, as a way to find where the target task is. ServiceClient,
through SpecificTaskServiceLocator, caches these target locations
for a period of time.
* Style adjustments.
* For the coverage.
* Adjustments.
* Better behaviors.
* Fixes.
The expiry timeout is compared against the current time but the condition is reversed.
This means that as soon as a supervisor task finishes, its partitions are cleaned up,
irrespective of the specified `intermediaryPartitionTimeout` period.
After these changes, the `intermediaryPartitionTimeout` will start getting honored.
Changes
* Fix the condition
* Add tests to verify the new correct behaviour
* Reduce the default expiry timeout from P1D to PT5M
to retain current behaviour in case of default configs.
This commit contains the cleanup needed for the new integration test framework.
Changes:
- Fix log lines, misspellings, docs, etc.
- Allow the use of some of Druid's "JSON config" objects in tests
- Fix minor bug in `BaseNodeRoleWatcher`
* Remove null and empty fields from native queries
* Test fixes
* Attempted IT fix.
* Revisions from review comments
* Build fixes resulting from changes suggested by reviews
* IT fix for changed segment size
The web-console (indirectly) calls the Overlord’s GET tasks API to fetch the tasks' summary which in turn queries the metadata tasks table. This query tries to fetch several columns, including payload, of all the rows at once. This introduces a significant memory overhead and can cause unresponsiveness or overlord failure when the ingestion tab is opened multiple times (due to several parallel calls to this API)
Another thing to note is that the task table (the payload column in particular) can be very large. Extracting large payloads from such tables can be very slow, leading to slow UI. While we are fixing the memory pressure in the overlord, we can also fix the slowness in UI caused by fetching large payloads from the table. Fetching large payloads also puts pressure on the metadata store as reported in the community (Metadata store query performance degrades as the tasks in druid_tasks table grows · Issue #12318 · apache/druid )
The task summaries returned as a response for the API are several times smaller and can fit comfortably in memory. So, there is an opportunity here to fix the memory usage, slow ingestion, and under-pressure metadata store by removing the need to handle large payloads in every layer we can. Of course, the solution becomes complex as we try to fix more layers. With that in mind, this page captures two approaches. They vary in complexity and also in the degree to which they fix the aforementioned problems.
* Clean up query contexts
Uses constants in place of literal strings for context keys.
Moves some QueryContext methods to QueryContexts for reuse.
* Revisions from review comments
* Add QoSFilters first in the chain.
When a request is suspended and later resumed due to QoS constraints,
its filter chain is restarted. Placing QoSFilters first in the chain
avoids double-execution of other filters.
Fixes an issue where requests deferred by QoS would report 403 Forbidden
due to double-execution of SecuritySanityCheckFilter.
* Smaller changes.
* Add QoS filters in BaseJettyTest.
* Remove unused parameter.
* SqlSegmentsMetadataQuery: Fix OVERLAPS for wide target segments.
Segments with endpoints prior to year 0 or after year 9999 may overlap
the search intervals but not match the generated SQL conditions. So, we
need to add an additional OR condition to catch these.
I checked a real, live MySQL metadata store to confirm that the query
still uses metadata store indexes. It does.
* Add comments.
Often users are submitting queries, and ingestion specs that work only if the relevant extension is not loaded. However, the error is too technical for the users and doesn't suggest them to check for missing extensions. This PR modifies the error message so users can at least check their settings before assuming that the error is because of a bug.
Adds a default implementation of getQueryContext, which was added to the Query interface in #12396. Query is marked with @ExtensionPoint, and lately we have been trying to be less volatile on these interfaces by providing default implementations to be more chill for extension writers.
The way this default implementation is done in this PR is a bit strange due to the way that getQueryContext is used (mutated with system default and system generated keys); the default implementation has a specific object that it returns, and I added another temporary default method isLegacyContext that checks if the getQueryContext returns that object or not. If not, callers fall back to using getContext and withOverriddenContext to set these default and system values.
I am open to other ideas as well, but this way should work at least without exploding, and added some tests to ensure that it is wired up correctly for QueryLifecycle, including the context authorization stuff.
The added test shows the strange behavior if query context authorization is enabled, mainly that the system default and system generated query context keys also need to be granted as permissions for things to function correctly. This is not great, so I mentioned it in the javadocs as well. Not sure if it needs to be called out anywhere else.
* Emit state of replace and append for native batch tasks
* Emit count of one depending on batch ingestion mode (APPEND, OVERWRITE, REPLACE)
* Add metric to compaction job
* Avoid null ptr exc when null emitter
* Coverage
* Emit tombstone & segment counts
* Tasks need a type
* Spelling
* Integrate BatchIngestionMode in batch ingestion tasks functionality
* Typos
* Remove batch ingestion type from metric since it is already in a dimension. Move IngestionMode to AbstractTask to facilitate having mode as a dimension. Add metrics to streaming. Add missing coverage.
* Avoid inner class referenced by sub-class inspection. Refactor computation of IngestionMode to make it more robust to null IOConfig and fix test.
* Spelling
* Avoid polluting the Task interface
* Rename computeCompaction methods to avoid ambiguous java compiler error if they are passed null. Other minor cleanup.
Issue:
Even though `CompactionTuningConfig` allows a `maxColumnsToMerge` config
(to optimize memory usage, particulary for datasources with many dimensions),
the corresponding client object `ClientCompactionTaskQueryTuningConfig`
(used by the coordinator duty `CompactSegments` to trigger auto-compaction)
does not contain this field. Thus, the value of `maxColumnsToMerge` specified
in any datasource compaction config is ignored.
Changes:
- Add field `maxColumnsToMerge` in `ClientCompactionTaskQueryTuningConfig`
and `UserCompactionTaskQueryTuningConfig`
- Fix tests
* Ensure ByteBuffers allocated in tests get freed.
Many tests had problems where a direct ByteBuffer would be allocated
and then not freed. This is bad because it causes flaky tests.
To fix this:
1) Add ByteBufferUtils.allocateDirect(size), which returns a ResourceHolder.
This makes it easy to free the direct buffer. Currently, it's only used
in tests, because production code seems OK.
2) Update all usages of ByteBuffer.allocateDirect (off-heap) in tests either
to ByteBuffer.allocate (on-heap, which are garbaged collected), or to
ByteBufferUtils.allocateDirect (wherever it seemed like there was a good
reason for the buffer to be off-heap). Make sure to close all direct
holders when done.
* Changes based on CI results.
* A different approach.
* Roll back BitmapOperationTest stuff.
* Try additional surefire memory.
* Revert "Roll back BitmapOperationTest stuff."
This reverts commit 49f846d9e3.
* Add TestBufferPool.
* Revert Xmx change in tests.
* Better behaved NestedQueryPushDownTest. Exit tests on OOME.
* Fix TestBufferPool.
* Remove T1C from ARM tests.
* Somewhat safer.
* Fix tests.
* Fix style stuff.
* Additional debugging.
* Reset null / expr configs better.
* ExpressionLambdaAggregatorFactory thread-safety.
* Alter forkNode to try to get better info when a JVM crashes.
* Fix buffer retention in ExpressionLambdaAggregatorFactory.
* Remove unused import.
Atul Mohan
imply-cheddar
zachjsh
Clint Wylie
Abhishek Agarwal
soullkk
Kashif Faraz
Paul Rogers
Adarsh Sanjeev
Gian Merlino
Karan Kumar
Tejaswini Bandlamudi
Suneet Saldanha
Lucas Capistrant
AmatyaAvadhanula
Maytas Monsereenusorn
somu-imply
Rishabh Singh
TSFenwick
Rohan Garg
Dr. Sizzles
Frank Chen
Adam Peck
zemin
Adam Peck
Santosh Pingale
Bartosz Mikulski
Gian Merlino
Agustin Gonzalez
superivaj