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.
* Fix dependency analyze warnings
Update the maven dependency plugin to the latest version and fix all
warnings for unused declared and used undeclared dependencies in the
compile scope. Added new travis job to add the check to CI. Also fixed
some source code files to use the correct packages for their imports and
updated druid-forbidden-apis to prevent regressions.
* Address review comments
* Adjust scope for org.glassfish.jaxb:jaxb-runtime
* Fix dependencies for hdfs-storage
* Consolidate netty4 versions
* Fix dependency analyze warnings
Update the maven dependency plugin to the latest version and fix all
warnings for unused declared and used undeclared dependencies in the
compile scope. Added new travis job to add the check to CI. Also fixed
some source code files to use the correct packages for their imports.
* Fix licenses and dependencies
* Fix licenses and dependencies again
* Fix integration test dependency
* Address review comments
* Fix unit test dependencies
* Fix integration test dependency
* Fix integration test dependency again
* Fix integration test dependency third time
* Fix integration test dependency fourth time
* Fix compile error
* Fix assert package
* Add checkstyle rules about imports and empty lines between members
* Add suppressions
* Update Eclipse import order
* Add empty line
* Fix StatsDEmitter
This PR accumulates many refactorings and small improvements that I did while preparing the next change set of https://github.com/druid-io/druid/projects/2. I finally decided to make them a separate PR to minimize the volume of the main PR.
Some of the changes:
- Renamed confusing "Generic Column" term to "Numeric Column" (what it actually implies) in many class names.
- Generified `ComplexMetricExtractor`
* Rename io.druid to org.apache.druid.
* Fix META-INF files and remove some benchmark results.
* MonitorsConfig update for metrics package migration.
* Reorder some dimensions in inner queries for some reason.
* Fix protobuf tests.
* Remove some unnecessary task storage internal APIs.
- Remove MetadataStorageActionHandler's getInactiveStatusesSince and getActiveEntriesWithStatus.
- Remove TaskStorage's getCreatedDateTimeAndDataSource.
- Remove TaskStorageQueryAdapter's getCreatedTime, and getCreatedDateAndDataSource.
- Migrated all callers to getActiveTaskInfo and getCompletedTaskInfo.
This has one side effect: since getActiveTaskInfo (new) warns and continues when it
sees unreadable tasks, but getActiveEntriesWithStatus threw an exception when it
encountered those, it means that after this patch bad tasks will be ignored when
syncing from metadata storage rather than causing an exception to be thrown.
IMO, this is an improvement, since the most likely reason for bad tasks is either:
- A new version introduced an additional validation, and a pre-existing task doesn't
pass it.
- You are rolling back from a newer version to an older version.
In both cases, I believe you would want to skip tasks that can't be deserialized,
rather than blocking overlord startup.
* Remove unused import.
* Fix formatting.
* Fix formatting.
* Remove some unnecessary use of boxed types.
* Fix some incorrect format strings.
* Enable IDEA's MalformedFormatString inspection.
* Add a Checkstyle check for finding uses of incorrect logging packages.
* Fix some incorrect usages of the metamx logger.
* Bypass incorrect logger Checkstyle check where using the correct logger is not simple.
* Fix some more places where the wrong number of arguments are provided to format strings.
* Suppress `MalformedFormatString` inspection on legacy logging test.
* Use @SuppressWarnings rather than a noinspection suppression comment.
* Fix some more incorrect format strings.
* Suppress some more incorrect format string warnings where the incorrect string is intentional.
* Log the aggregator when closing it fails.
* Remove some unneeded log lines.
* Avoid usages of Default system Locale and printing to System.out or System.err in production code
* Fix Charset in DruidKerberosUtil
* Remove redundant string format in GenericIndexed
* Rename StringUtils.safeFormat() to unimportantSafeFormat(); add StringUtils.format() which fails as well as String.format()
* Fix testSafeFormat()
* More fixes of redundant StringUtils.format() inside ISE
* Rename unimportantSafeFormat() to nonStrictFormat()
* Make PolyBind to fail if property value is not found
* Fix test
* Add onHeap option in NamespaceExtractionModule
* Add PolyBind.createChoiceWithDefaultNoScope()
* Fix NPE
* Fix
* Configure MetadataStorageProvider option for MySQL, PostgreSQL and SQLServer
* Deprecate PolyBind.createChoiceWithDefault form with unused defaultKey
* Fix NPE
* modified "end" column to `end`. "end" is interpretted as a string rather than dereferencing the column value
* SQLMetadataConnector.getQuoteString defines the string that should be used to quote string fields
* positional arguments for String.format
* for Connectors that use " need to include the \ escape as well
Kashif Faraz
Abhishek Agarwal
AmatyaAvadhanula
Clint Wylie
Jihoon Son
Jonathan Wei
jon-wei
Chi Cao Minh
Roman Leventov
David Lim
Clint Wylie
David Lim
Gian Merlino
Chris Gavin
michaelschiff
Himanshu
Mark