TaskDescription¶

TaskDescription is a metadata of a Task.

Creating Instance¶

TaskDescription takes the following to be created:

• Task ID
• Task attempt number
• Executor ID
• Task name
• Task index (within the TaskSet)
• Partition ID
• Added files (as Map[String, Long])
• Added JAR files (as Map[String, Long])
• Properties
• Resources
• Serialized task (as ByteBuffer)

TaskDescription is created when:

• TaskSetManager is requested to find a task ready for execution (given a resource offer)

Resources¶

resources: Map[String, ResourceInformation]

TaskDescription is given resources when created.

The resources are either specified when TaskSetManager is requested to resourceOffer (and prepareLaunchingTask) or decoded from bytes.

Text Representation¶

toString: String

toString uses the taskId and index as follows:

TaskDescription(TID=[taskId], index=[index])

Decoding TaskDescription (from Serialized Format)¶

decode(
  byteBuffer: ByteBuffer): TaskDescription

decode simply decodes (<>) a TaskDescription from the serialized format (ByteBuffer).

Internally, decode...FIXME

decode is used when:

• CoarseGrainedExecutorBackend is requested to CoarseGrainedExecutorBackend.md#LaunchTask[handle a LaunchTask message]

• Spark on Mesos' MesosExecutorBackend is requested to spark-on-mesos:spark-executor-backends-MesosExecutorBackend.md#launchTask[launch a task]

Encoding TaskDescription (to Serialized Format)¶

encode(
  taskDescription: TaskDescription): ByteBuffer

encode simply encodes the TaskDescription to a serialized format (ByteBuffer).

Internally, encode...FIXME

encode is used when:

• DriverEndpoint (of CoarseGrainedSchedulerBackend) is requested to launchTasks

Task Name¶

The name of the task is of the format:

task [taskID] in stage [taskSetID]