============= Task Resource

The Task resource provides a set of REST endpoints that give Presto servers the ability to communicate about tasks and task output. This isn't a service that will be used by end users, but it supports the execution of queries on a Presto installation.

.. function:: GET /v1/task

Returns information about all tasks known to a Presto server.

Note that the output of a call to /v1/task can be quite large. If you execute this against a busy Presto server the response received will include a listing of every task known to that server along with detailed statistics about operators and drivers.

The following example response shows a trivial task response that has been truncated to fit this manual. A real response from a busy Presto server would generate pages and pages of output. Here there is a taskId for a task which is in the CANCELED state.

Example response:

.. sourcecode:: json

  [ {
    "taskId" : "20131222_183944_00011_dk5x2.1.0",
    "version" : 9223372036854775807,
    "state" : "CANCELED",
    "self" : "unknown",
    "lastHeartbeat" : "2013-12-22T13:54:46.566-05:00",
    "outputBuffers" : {
      "state" : "FINISHED",
      "masterSequenceId" : 0,
      "pagesAdded" : 0,
      "buffers" : [ ]
    },
    "noMoreSplits" : [ ],
    "stats" : {
      "createTime" : "2013-12-22T13:54:46.566-05:00",
      "elapsedTime" : "0.00ns",
      "queuedTime" : "92.00us",
      "totalDrivers" : 0,
      "queuedDrivers" : 0,
      "runningDrivers" : 0,
      "completedDrivers" : 0,
      "memoryReservation" : "0B",
      "totalScheduledTime" : "0.00ns",
      "totalCpuTime" : "0.00ns",
      "totalBlockedTime" : "0.00ns",
      "rawInputDataSize" : "0B",
      "rawInputPositions" : 0,
      "processedInputDataSize" : "0B",
      "processedInputPositions" : 0,
      "outputDataSize" : "0B",
      "outputPositions" : 0,
      "pipelines" : [ ]
    },
    "failures" : [ ],
    "outputs" : { }
  }]

.. function:: POST /v1/task/{taskId}

.. function:: DELETE /v1/task/{taskId}

Deletes a given task from a Presto server.

.. function:: GET /v1/task/{taskId}

Retrieves information about a specific task by taskId.

The following example lists the output of a task. It contains the following high-level sections:

outputBuffers
noMoreSplits
stats
failures
outputs

This is the same output that is also present in the response from the Query resource which lists all of the stages and tasks involved in a particular query. This is call is used by Presto to coordinate a queries.

Example response:

.. sourcecode:: json

  {
"taskId" : "20140115_170528_00004_dk5x2.0.0",
"version" : 42,
"state" : "FINISHED",
"self" : "http://10.193.207.128:8080/v1/task/20140115_170528_00004_dk5x2.0.0",
"lastHeartbeat" : "2014-01-15T12:12:12.518-05:00",
"outputBuffers" : {
  "state" : "FINISHED",
  "masterSequenceId" : 0,
  "pagesAdded" : 1,
  "buffers" : [ {
    "bufferId" : "out",
    "finished" : true,
    "bufferedPages" : 0,
    "pagesSent" : 1
  } ]
},
"noMoreSplits" : [ "8" ],
"stats" : {
  "createTime" : "2014-01-15T12:12:08.520-05:00",
  "startTime" : "2014-01-15T12:12:08.526-05:00",
  "endTime" : "2014-01-15T12:12:12.518-05:00",
  "elapsedTime" : "4.00s",
  "queuedTime" : "6.39ms",
  "totalDrivers" : 1,
  "queuedDrivers" : 0,
  "runningDrivers" : 0,
  "completedDrivers" : 1,
  "memoryReservation" : "174.76kB",
  "totalScheduledTime" : "4.19ms",
  "totalCpuTime" : "4.09ms",
  "totalBlockedTime" : "29.50ms",
  "rawInputDataSize" : "10.90kB",
  "rawInputPositions" : 154,
  "processedInputDataSize" : "10.90kB",
  "processedInputPositions" : 154,
  "outputDataSize" : "10.90kB",
  "outputPositions" : 154,
  "pipelines" : [ {
    "inputPipeline" : true,
    "outputPipeline" : true,
    "totalDrivers" : 1,
    "queuedDrivers" : 0,
    "runningDrivers" : 0,
    "completedDrivers" : 1,
    "memoryReservation" : "0B",
    "queuedTime" : {
      "maxError" : 0.0,
      "count" : 1.0,
      "total" : 5857000.0,
      "p01" : 5857000,
      "p05" : 5857000,
      "p10" : 5857000,
      "p25" : 5857000,
      "p50" : 5857000,
      "p75" : 5857000,
      "p90" : 5857000,
      "p95" : 5857000,
      "p99" : 5857000,
      "min" : 5857000,
      "max" : 5857000
    },
    "elapsedTime" : {
      "maxError" : 0.0,
      "count" : 1.0,
      "total" : 4.1812E7,
      "p01" : 41812000,
      "p05" : 41812000,
      "p10" : 41812000,
      "p25" : 41812000,
      "p50" : 41812000,
      "p75" : 41812000,
      "p90" : 41812000,
      "p95" : 41812000,
      "p99" : 41812000,
      "min" : 41812000,
      "max" : 41812000
    },
    "totalScheduledTime" : "4.19ms",
    "totalCpuTime" : "4.09ms",
    "totalBlockedTime" : "29.50ms",
    "rawInputDataSize" : "10.90kB",
    "rawInputPositions" : 154,
    "processedInputDataSize" : "10.90kB",
    "processedInputPositions" : 154,
    "outputDataSize" : "10.90kB",
    "outputPositions" : 154,
    "operatorSummaries" : [ {
      "operatorId" : 0,
      "operatorType" : "ExchangeOperator",
      "addInputCalls" : 0,
      "addInputWall" : "0.00ns",
      "addInputCpu" : "0.00ns",
      "addInputUser" : "0.00ns",
      "inputDataSize" : "10.90kB",
      "inputPositions" : 154,
      "getOutputCalls" : 1,
      "getOutputWall" : "146.00us",
      "getOutputCpu" : "137.90us",
      "getOutputUser" : "0.00ns",
      "outputDataSize" : "10.90kB",
      "outputPositions" : 154,
      "blockedWall" : "29.50ms",
      "finishCalls" : 0,
      "finishWall" : "0.00ns",
      "finishCpu" : "0.00ns",
      "finishUser" : "0.00ns",
      "memoryReservation" : "0B",
      "info" : {
	"bufferedBytes" : 0,
	"averageBytesPerRequest" : 11158,
	"bufferedPages" : 0,
	"pageBufferClientStatuses" : [ {
	  "uri" : "http://10.193.207.128:8080/v1/task/20140115_170528_00004_dk5x2.1.0/results/ab68e201-3878-4b21-b6b9-f6658ddc408b",
	  "state" : "closed",
	  "lastUpdate" : "2014-01-15T12:12:08.562-05:00",
	  "pagesReceived" : 1,
	  "requestsScheduled" : 3,
	  "requestsCompleted" : 3,
	  "httpRequestState" : "queued"
	} ]
      }
    }, {
      "operatorId" : 1,
      "operatorType" : "FilterAndProjectOperator",
      "addInputCalls" : 1,
      "addInputWall" : "919.00us",
      "addInputCpu" : "919.38us",
      "addInputUser" : "0.00ns",
      "inputDataSize" : "10.90kB",
      "inputPositions" : 154,
      "getOutputCalls" : 2,
      "getOutputWall" : "128.00us",
      "getOutputCpu" : "128.64us",
      "getOutputUser" : "0.00ns",
      "outputDataSize" : "10.45kB",
      "outputPositions" : 154,
      "blockedWall" : "0.00ns",
      "finishCalls" : 5,
      "finishWall" : "258.00us",
      "finishCpu" : "253.19us",
      "finishUser" : "0.00ns",
      "memoryReservation" : "0B"
    }, {
      "operatorId" : 2,
      "operatorType" : "OrderByOperator",
      "addInputCalls" : 1,
      "addInputWall" : "438.00us",
      "addInputCpu" : "439.18us",
      "addInputUser" : "0.00ns",
      "inputDataSize" : "10.45kB",
      "inputPositions" : 154,
      "getOutputCalls" : 4,
      "getOutputWall" : "869.00us",
      "getOutputCpu" : "831.85us",
      "getOutputUser" : "0.00ns",
      "outputDataSize" : "10.45kB",
      "outputPositions" : 154,
      "blockedWall" : "0.00ns",
      "finishCalls" : 4,
      "finishWall" : "808.00us",
      "finishCpu" : "810.18us",
      "finishUser" : "0.00ns",
      "memoryReservation" : "174.76kB"
    }, {
      "operatorId" : 3,
      "operatorType" : "FilterAndProjectOperator",
      "addInputCalls" : 1,
      "addInputWall" : "166.00us",
      "addInputCpu" : "166.66us",
      "addInputUser" : "0.00ns",
      "inputDataSize" : "10.45kB",
      "inputPositions" : 154,
      "getOutputCalls" : 5,
      "getOutputWall" : "305.00us",
      "getOutputCpu" : "241.14us",
      "getOutputUser" : "0.00ns",
      "outputDataSize" : "10.90kB",
      "outputPositions" : 154,
      "blockedWall" : "0.00ns",
      "finishCalls" : 2,
      "finishWall" : "70.00us",
      "finishCpu" : "71.02us",
      "finishUser" : "0.00ns",
      "memoryReservation" : "0B"
    }, {
      "operatorId" : 4,
      "operatorType" : "TaskOutputOperator",
      "addInputCalls" : 1,
      "addInputWall" : "50.00us",
      "addInputCpu" : "51.03us",
      "addInputUser" : "0.00ns",
      "inputDataSize" : "10.90kB",
      "inputPositions" : 154,
      "getOutputCalls" : 0,
      "getOutputWall" : "0.00ns",
      "getOutputCpu" : "0.00ns",
      "getOutputUser" : "0.00ns",
      "outputDataSize" : "10.90kB",
      "outputPositions" : 154,
      "blockedWall" : "0.00ns",
      "finishCalls" : 1,
      "finishWall" : "35.00us",
      "finishCpu" : "35.39us",
      "finishUser" : "0.00ns",
      "memoryReservation" : "0B"
    } ],
    "drivers" : [ ]
  } ]
},
"failures" : [ ],
"outputs" : { }
  }

.. function:: GET /v1/task/{taskId}/results/{outputId}/{token}

This service is used by Presto to retrieve task output.

.. function:: DELETE /v1/task/{taskId}/results/{outputId}

This service is used by Presto to delete task output.