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

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

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

Elements of the acls object

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:

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

CounterGroup Object

Counter Object

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.

Property Object

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:

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

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:

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

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