PerfectHadoop: MapReduce Application

This project provides a Swift wrapper of MapReduce Application Master REST API:

  • MapReduceApplication(): access a specific map / reduce application running on current server.

RELEASE NOTE

⚠️This is an experimental module and is subject to change in future. ⚠️

Connect to Hadoop Map Reduce Application

To connect to a current active Hadoop Map / Reduce Application by Perfect, initialize a MapReduceApplication() object with an APPLICATION ID, and other essential parameters:

// this connection could possibly do some basic operations
let app = MapReduceApplication(applicationId: "application_12345678_xxxxxx", host: "mapReducer.somedomain.com")

you can also

// add user name if need
let app = MapReduceApplication(applicationId: "application_12345678_xxxxxx", host: "mapReducer.somedomain.com", user: "your user name")

Authentication

If using Kerberos to authenticate, please try codes below:

// set auth to kerberos
let app = MapReduceApplication(applicationId: "application_12345678_xxxxxx", host: "mapReducer.somedomain.com", user: "your user name", auth: .krb5)

Parameters of MapReduceApplication Object

Item|Data Type|Description ----|---------|----------- applicationId|String|the id string of the application to control. Required service|String|the service protocol of web request - http / https host|String|the hostname or ip address of the Hadoop Map Reduce Application Master host port|Int|the port of map reduce application master host, default is 8088 auth| Authorization| .off or .krb5. Default value is .off proxyUser|String|proxy user, if applicable apibase|String|use this parameter ONLY the target server has a different api routine other than /ws/v1/mapreduce timeout`:Int, timeout in seconds, zero means never timeout during transfer

Get General Information

Call checkInfo() to get the general information of a Hadoop MapReduce Application Master in form of a MapReduceApplication.Info structure:

guard let inf = try app.checkInfo() else {
    // something goes wrong here
}
print(inf.startedOn)
print(inf.hadoopVersion)
print(inf.hadoopBuildVersion)
print(inf.hadoopVersionBuiltOn)

Members of MapReduceApplication.Info

Item|Data Type|Description ----|---------|----------- appId|Int|The application id startedOn|Int|The time the application started (in ms since epoch) name|string|The name of the application user|string|The user name of the user who started the application elapsedTime|long|The time since the application was started (in ms)

MapReduce Jobs

Call checkJobs() to return an array of Job structure. The jobs resource provides a list of the MapReduce jobs that have finished. It does not currently return a full list of parameters. The simplest form is checkJobs(), which will return all jobs available:

let jobs = try app.checkJobs()
jobs.forEach { j in
  print(j.id)
  print(j.name)
  print(j.queue)
  print(j.state)
}

If succeeded, checkJobs() would probably return a job object as described below:

Data Structure of Job

Item|Data Type|Description ----|---------|----------- id|String|The job id name|String|The job name queue|String|The queue the job was submitted to user|String|The user name state|String|the job state - valid values are: NEW, INITED, RUNNING, SUCCEEDED, FAILED, KILL_WAIT, KILLED, ERROR startTime|Int|The time the job started (in ms since epoch) finishTime|Int|The time the job finished (in ms since epoch) elapsedTime|Int|The elapsed time since job started (in ms) mapsTotal|Int|The total number of maps mapsCompleted|Int|The number of completed maps reducesTotal|Int|The total number of reduces reducesCompleted|Int|The number of completed reduces diagnostics|String|A diagnostic message uberized|Bool|Indicates if the job was an uber job - ran completely in the application master mapsPending|Int|The number of maps still to be run mapsRunning|Int|The number of running maps reducesPending|Int|The number of reduces still to be run reducesRunning|Int|The number of running reduces failedReduceAttempts|Int|The number of failed reduce attempts killedReduceAttempts|Int|The number of killed reduce attempts successfulReduceAttempts|Int|The number of successful reduce attempts failedMapAttempts|Int|The number of failed map attempts killedMapAttempts|Int|The number of killed map attempts successfulMapAttempts|Int|The number of successful map attempts acls|[ACL]|A collection of acls objects

Elements of the acls object

Item|Data Type|Description ----|---------|----------- value|String|The acl value name|String|The acl name

Check a Specific Job

It is also possible to check a specific job by a job id:

let job = try app.checkJob(jobId: "job_1484231633049_0005")

See Data Structure of Job as above.

JobAttempt of Job

When you make a request for the list of job attempts, the information will be returned as an array of job attempt objects.

guard let attempts = try app.checkJobAttempts(jobId: "job_1484231633049_0005") else {
    // something goes wrong
}
attempts.forEach { attempt in
    print(attempt.id)
    print(attempt.containerId)
    print(attempt.nodeHttpAddress)
    print(attempt.nodeId)
    print(attempt.startTime)
}

JobAttempt Structure:

Item|Data Type|Description ----|---------|----------- id|String|The job attempt id nodeId|String|The node id of the node the attempt ran on nodeHttpAddress|String|The node http address of the node the attempt ran on logsLink|String|The http link to the job attempt logs containerId|String|The id of the container for the job attempt startTime|Long|The start time of the attempt (in ms since epoch)

Counters of Job

With the job counters API, you can object a collection of resources that represent al the counters for that job.

guard let js = try app.checkJobCounters(jobId: "job_1484231633049_0005") else {
    // something wrong
}//end guard
js.counterGroup.forEach{ group in
  print(group.counterGroupName)
  group.counters.forEach { counter in
    print(counter.name)
    print(counter.mapCounterValue)
    print(counter.reduceCounterValue)
    print(counter.totalCounterValue)
  }//next counter
}//next group

JobCounter Object

Item|Data Type|Description ----|---------|----------- id|String|The job id counterGroup|[CounterGroup]|An array of counter group objects

CounterGroup Object

Item|Data Type|Description ----|---------|----------- counterGroupName|string|The name of the counter group counter|[Counter]|An array of counter objects

Counter Object

Item|Data Type|Description ----|---------|----------- name|String|The name of the counter reduceCounterValue|Int|The counter value of reduce tasks mapCounterValue|Int|The counter value of map tasks totalCounterValue|Int|The counter value of all tasks

Check Configuration of Job

Use checkJobConfig() to check configuration of a specific job:

gurard let config = try app.checkJobConfig(jobId: "job_1484231633049_0005") else {
    /// something wrong
}
// print the configuration path
print(config.path)
// check properties of configuration file
for p in config.property {
  print(p.name)
  print(p.value)
  print(p.source)
}

JobConfig Object

A job configuration resource contains information about the job configuration for this job.

Item|Data Type|Description ----|---------|----------- path|String|The path to the job configuration file property|[Property]| an array of property object

Property Object

Item|Data Type|Description ----|---------|----------- name|String|The name of the configuration property value|String|The value of the configuration property source|String|The location this configuration object came from. If there is more then one of these it shows the history with the latest source at the end of the list.

Tasks of a Job

Use checkJobTasks() to collect task information from a specific job:

// get all tasks information from a specific job
let tasks = try app.checkJobTasks(jobId: "job_1484231633049_0005")

// print properties of each task
for t in tasks {
  print(t.progress)
  print(t.elapsedTime)
  print(t.state)
  print(t.startTime)
  print(t.id)
  print(t.type)
  print(t.successfulAttempt)
  print(t.finishTime)
}//next t

Parameters of checkJobTasks()

Calling checkJobTasks() requires a jobId all the time, however, you can also specify an extra parameter to indicate what type of tasks shall be listed in the query results:

  • jobId: a string represents the id of the job
  • taskType: optional, could be .MAP or .REDUCE

JobTask Object

The checkJobTasks() will return an array of JobTask data structure, as described below:

Item|Data Type|Description ----|---------|----------- id|string|The task id state|String|The state of the task - valid values are: NEW, SCHEDULED, RUNNING, SUCCEEDED, FAILED, KILL_WAIT, KILLED type|String|The task type - MAP or REDUCE successfulAttempt|String|The id of the last successful attempt progress|Double|The progress of the task as a percent startTime|Int|The time in which the task started (in ms since epoch) or -1 if it was never started finishTime|Int|The time in which the task finished (in ms since epoch) elapsedTime|Int|The elapsed time since the application started (in ms)

Query a Specific JobTask

If both jobId and jobTaskId are available, you can use checkJobTask() to perform a query on a specific job task:

guard let task = try app.checkJobTask(jobId: "job_1484231633049_0005", taskId: "task_1326381300833_2_2_m_0") else {
    // something wrong
}
print(task.progress)

The return value of checkJobTask will be a JobTask object, as described above.

Task Counters of Job

Method checkJobTaskCounters() can return counters of a specific task, as the example below:

guard let js = try app.checkJobTaskCounters(jobId: "job_1484231633049_0005", taskId: "task_1326381300833_2_2_m_0") else {
    // something wrong
}
// print the id of the job task counters
print(js.id)
// check out each counter group
js.taskCounterGroup.forEach{ group in
  print(group.counterGroupName)
  // print counters in each group.
  group.counters.forEach { counter in
    print(counter.name)
    print(counter.value)
  }
}

JobTaskCounter Object

Item|Data Type|Description ----|---------|----------- id|String|The job id taskCounterGroup|[CounterGroup]|An array of counter group objects, See CounterGroup

Task Attempts

Function checkJobTaskAttempts() can return attempts from a specific job task.

let jobTaskAttempts = try app.checkJobTaskAttempts(jobId: "job_1484231633049_0005", taskId: "task_1326381300833_2_2_m_0")
for attempt in jobTaskAttempts {
  print(attempt.id)
  print(attempt.diagnostics)
  print(attempt.assignedContainerId)
  print(attempt.rack)
  print(attempt.state)
  print(attempt.progress)
}//next

Once done, the checkJobTaskAttempts will return an array of TaskAttempt object, as described below:

TaskAttempt Object

Elements of the TaskAttempt object:

Item|Data Type|Description ----|---------|----------- id|String|The task id rack|String|The rack state|TaskAttempt.State|The state of the task attempt - valid values are: NEW, UNASSIGNED, ASSIGNED, RUNNING, COMMITPENDING, SUCCESSCONTAINERCLEANUP, SUCCEEDED, FAILCONTAINERCLEANUP, FAILTASKCLEANUP, FAILED, KILLCONTAINERCLEANUP, KILLTASK_CLEANUP, KILLED type|TaskType|The type of task - MAP or REDUCE assignedContainerId|String|The container id this attempt is assigned to nodeHttpAddress|String|The http address of the node this task attempt ran on diagnostics|String|A diagnostics message progress|Double|The progress of the task attempt as a percent startTime|Int|The time in which the task attempt started (in ms since epoch) finishTime|Int|The time in which the task attempt finished (in ms since epoch) elapsedTime|Int|The elapsed time since the task attempt started (in ms)

Besides, For reduce task attempts you also have the following fields:

Item|Data Type|Description ----|---------|----------- shuffleFinishTime|Int|The time at which shuffle finished (in ms since epoch) mergeFinishTime|Int|The time at which merge finished (in ms since epoch) elapsedShuffleTime|Int|The time it took for the shuffle phase to complete (time in ms between reduce task start and shuffle finish) elapsedMergeTime|Int|The time it took for the merge phase to complete (time in ms between the shuffle finish and merge finish) elapsedReduceTime|Int|The time it took for the reduce phase to complete (time in ms between merge finish to end of reduce task)

Query a Specific TaskAttempt

If a taskAttempt id is available, you can also check the specific one by checkJobTaskAttempt(), as demo below:

guard let jobTaskAttempts = try app.checkJobTaskAttempt(jobId: "job_1484231633049_0005", taskId: "task_1326381300833_2_2_m_0", "attempt_1326381300833_2_2_m_0_0") else {
    // something wrong
    print("there is no such a task attempt")
    return
}//end guard
print(attempt.id)
print(attempt.diagnostics)
print(attempt.assignedContainerId)
print(attempt.rack)
print(attempt.state)
print(attempt.progress)

The checkJobTaskAttempt() will return such an TaskAttempt object as described above.

Attempt State Control

Currently Hadoop MapReduce Application Master has an experimental attempt state control.

Check Attempt

To check a running attempt state, use checkJobTaskAttemptState(): swift guard let state = try checkJobTaskAttemptState(jobId: "job_1484231633049_0005", taskId: "task_1326381300833_2_2_m_0", "attempt_1326381300833_2_2_m_0_0") else { // something wrong print("there is no such a task attempt") return }//end guard print(state)

Kill Attempt

To terminate an attempt, call killTaskAttempt():

try killTaskAttempt(jobId: "job_1484231633049_0005", taskId: "task_1326381300833_2_2_m_0", "attempt_1326381300833_2_2_m_0_0")

Attempt Counters of Task

Method checkJobTaskAttemptCounters() can return counters of a specific task attempt, as the example below:

guard let counters = try app.checkJobTaskAttemptCounters(jobId: "job_1484231633049_0005", taskId: "task_1326381300833_2_2_m_0", "attempt_1326381300833_2_2_m_0_0") else {
    // something wrong
    print("Task Attempt Counters Acquiring failed")
    return 
}
// print the counters' id
print(counters.id)
// enumerate all groups
for group in counters.taskAttemptCounterGroup {
  // print group name
  print(group.counterGroupName)
  // enumerate all counters in this group
  for counter in group.counters {
    print(counter.name)
    print(counter.value)
  }//next counter
}//next group
}

JobTaskAttemptCounters Object

Item|Data Type|Description ----|---------|----------- id|String|The job id taskAttemptcounterGroup |[CounterGroup]|An array of counter group objects, See CounterGroup