spark-webui-executors-ExecutorsListener.adoc

ExecutorsListener Spark Listener

ExecutorsListener is a SparkListener that tracks executors and their tasks in a Spark application for Stage Details page, Jobs tab and /allexecutors REST endpoint.

Table 1. ExecutorsListener’s SparkListener Callbacks (in alphabetical order)

Event Handler	Description
onApplicationStart	May create an entry for the driver in executorToTaskSummary registry
onExecutorAdded	May create an entry in executorToTaskSummary registry. It also makes sure that the number of entries for dead executors does not exceed spark.ui.retainedDeadExecutors and removes excess. Adds an entry to executorEvents registry and optionally removes the oldest if the number of entries exceeds spark.ui.timeline.executors.maximum.
onExecutorBlacklisted	FIXME
onExecutorRemoved	Marks an executor dead in executorToTaskSummary registry. Adds an entry to executorEvents registry and optionally removes the oldest if the number of entries exceeds spark.ui.timeline.executors.maximum.
onExecutorUnblacklisted	FIXME
onNodeBlacklisted	FIXME
onNodeUnblacklisted	FIXME
onTaskStart	May create an entry for an executor in executorToTaskSummary registry.
onTaskEnd	May create an entry for an executor in executorToTaskSummary registry.

ExecutorsListener requires a StorageStatusListener and SparkConf.

Table 2. ExecutorsListener’s Internal Registries and Counters

Registry	Description
executorToTaskSummary	The lookup table for ExecutorTaskSummary per executor id. Used to build a ExecutorSummary for /allexecutors REST endpoint, to display stdout and stderr logs in Tasks and Aggregated Metrics by Executor sections in Stage Details page.
executorEvents	A collection of SparkListenerEvents. Used to build the event timeline in AllJobsPage and Details for Job pages.

updateExecutorBlacklist Method

Caution

FIXME

Intercepting Executor Was Blacklisted Events — onExecutorBlacklisted Callback

Caution

FIXME

Intercepting Executor Is No Longer Blacklisted Events — onExecutorUnblacklisted Callback

Caution

FIXME

Intercepting Node Was Blacklisted Events — onNodeBlacklisted Callback

Caution

FIXME

Intercepting Node Is No Longer Blacklisted Events — onNodeUnblacklisted Callback

Caution

FIXME

Intercepting Application Started Events — onApplicationStart Callback

onApplicationStart(applicationStart: SparkListenerApplicationStart): Unit

Note	onApplicationStart is part of SparkListener contract to announce that a Spark application has been started.

onApplicationStart takes driverLogs property from the input applicationStart (if defined) and finds the driver’s active StorageStatus (using the current StorageStatusListener). onApplicationStart then uses the driver’s StorageStatus (if defined) to set executorLogs.

Table 3. ExecutorTaskSummary and ExecutorInfo Attributes

ExecutorTaskSummary Attribute	SparkListenerApplicationStart Attribute
executorLogs	driverLogs (if defined)

Intercepting Executor Added Events — onExecutorAdded Callback

onExecutorAdded(executorAdded: SparkListenerExecutorAdded): Unit

Note	onExecutorAdded is part of SparkListener contract to announce that a new executor has been registered with the Spark application.

onExecutorAdded finds the executor (using the input executorAdded) in the internal executorToTaskSummary registry and sets the attributes. If not found, onExecutorAdded creates a new entry.

Table 4. ExecutorTaskSummary and ExecutorInfo Attributes

ExecutorTaskSummary Attribute	ExecutorInfo Attribute
executorLogs	logUrlMap
totalCores	totalCores
tasksMax	totalCores / spark.task.cpus

onExecutorAdded adds the input executorAdded to executorEvents collection. If the number of elements in executorEvents collection is greater than spark.ui.timeline.executors.maximum configuration property, the first/oldest event is removed.

onExecutorAdded removes the oldest dead executor from executorToTaskSummary lookup table if their number is greater than spark.ui.retainedDeadExecutors.

Intercepting Executor Removed Events — onExecutorRemoved Callback

onExecutorRemoved(executorRemoved: SparkListenerExecutorRemoved): Unit

Note	onExecutorRemoved is part of SparkListener contract to announce that an executor has been unregistered with the Spark application.

onExecutorRemoved adds the input executorRemoved to executorEvents collection. It then removes the oldest event if the number of elements in executorEvents collection is greater than spark.ui.timeline.executors.maximum configuration property.

The executor is marked as removed/inactive in executorToTaskSummary lookup table.

Intercepting Task Started Events — onTaskStart Callback

onTaskStart(taskStart: SparkListenerTaskStart): Unit

Note	onTaskStart is part of SparkListener contract to announce that a task has been started.

onTaskStart increments tasksActive for the executor (using the input SparkListenerTaskStart).

Table 5. ExecutorTaskSummary and SparkListenerTaskStart Attributes

ExecutorTaskSummary Attribute	Description
tasksActive	Uses taskStart.taskInfo.executorId.

Intercepting Task End Events — onTaskEnd Callback

onTaskEnd(taskEnd: SparkListenerTaskEnd): Unit

Note	onTaskEnd is part of SparkListener contract to announce that a task has ended.

onTaskEnd takes TaskInfo from the input taskEnd (if available).

Depending on the reason for SparkListenerTaskEnd onTaskEnd does the following:

Table 6. onTaskEnd Behaviour per SparkListenerTaskEnd Reason

SparkListenerTaskEnd Reason	onTaskEnd Behaviour
Resubmitted	Does nothing
ExceptionFailure	Increment tasksFailed
anything	Increment tasksComplete

tasksActive is decremented but only when the number of active tasks for the executor is greater than 0.

Table 7. ExecutorTaskSummary and onTaskEnd Behaviour

ExecutorTaskSummary Attribute	Description
tasksActive	Decremented if greater than 0.
duration	Uses taskEnd.taskInfo.duration

If the TaskMetrics (in the input taskEnd) is available, the metrics are added to the taskSummary for the task’s executor.

Table 8. Task Metrics and Task Summary

Task Summary	Task Metric
inputBytes	inputMetrics.bytesRead
inputRecords	inputMetrics.recordsRead
outputBytes	outputMetrics.bytesWritten
outputRecords	outputMetrics.recordsWritten
shuffleRead	shuffleReadMetrics.remoteBytesRead
shuffleWrite	shuffleWriteMetrics.bytesWritten
jvmGCTime	metrics.jvmGCTime

Finding Active BlockManagers — activeStorageStatusList Method

activeStorageStatusList: Seq[StorageStatus]

activeStorageStatusList requests StorageStatusListener for active BlockManagers (on executors).

Note	activeStorageStatusList is used when: FIXME AllExecutorListResource does executorList ExecutorListResource does executorList ExecutorsListener gets informed that the Spark application has started, onNodeBlacklisted, and onNodeUnblacklisted