Package org.apache.tools.ant.taskdefs

# Class Parallel

java.lang.Object
org.apache.tools.ant.ProjectComponent
org.apache.tools.ant.Task
org.apache.tools.ant.taskdefs.Parallel

All Implemented Interfaces:
  `java.lang.Cloneable`, `TaskContainer`

    public class Parallel
    extends Task
    implements TaskContainer

Executes the contained tasks in separate threads, continuing once all are completed.

New behavior allows for the ant script to specify a maximum number of threads that will be executed in parallel. One should be very careful about using the `waitFor` task when specifying `threadCount` as it can cause deadlocks if the number of threads is too small or if one of the nested tasks fails to execute completely. The task selection algorithm will insure that the tasks listed before a task have started before that task is started, but it will not insure a successful completion of those tasks or that those tasks will finish first (i.e. it's a classic race condition).

Since:
  Ant 1.4

- ## Nested Class Summary

  Nested Classes
  Modifier and Type | Class | Description
  --- | --- | ---
  `static class` | `Parallel.TaskList` | Class which holds a list of tasks to execute

- ## Field Summary

  ### Fields inherited from class org.apache.tools.ant.Task

  `target, taskName, taskType, wrapper`

  ### Fields inherited from class org.apache.tools.ant.ProjectComponent

  `description, location, project`

- ## Constructor Summary

  Constructors
  Constructor | Description
  --- | ---
  `Parallel()` |

- ## Method Summary

  Modifier and Type | Method | Description
  --- | --- | ---
  `void` | `addDaemons​(Parallel.TaskList daemonTasks)` | Add a group of daemon threads
  `void` | `addTask​(Task nestedTask)` | Add a nested task to execute in parallel.
  `void` | `execute()` | Execute the parallel tasks
  `void` | `setFailOnAny​(boolean failOnAny)` | Control whether a failure in a nested task halts execution.
  `void` | `setPollInterval​(int pollInterval)` | Interval to poll for completed threads when threadCount or threadsPerProcessor is specified.
  `void` | `setThreadCount​(int numThreads)` | Statically determine the maximum number of tasks to execute simultaneously.
  `void` | `setThreadsPerProcessor​(int numThreadsPerProcessor)` | Dynamically generates the number of threads to execute based on the number of available processors (via `java.lang.Runtime.availableProcessors()`).
  `void` | `setTimeout​(long timeout)` | Sets the timeout on this set of tasks.

  ### Methods inherited from class org.apache.tools.ant.Task

  `bindToOwner, getOwningTarget, getRuntimeConfigurableWrapper, getTaskName, getTaskType, getWrapper, handleErrorFlush, handleErrorOutput, handleFlush, handleInput, handleOutput, init, isInvalid, log, log, log, log, maybeConfigure, perform, reconfigure, setOwningTarget, setRuntimeConfigurableWrapper, setTaskName, setTaskType`

  ### Methods inherited from class org.apache.tools.ant.ProjectComponent

  `clone, getDescription, getLocation, getProject, setDescription, setLocation, setProject`

  ### Methods inherited from class java.lang.Object

  `equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- ## Constructor Details

  - ### Parallel

    public Parallel()

- ## Method Details

  - ### addDaemons

    public void addDaemons​(Parallel.TaskList daemonTasks)
    Add a group of daemon threads
    Parameters:
      `daemonTasks` - The tasks to be executed as daemon.

  - ### setPollInterval

    public void setPollInterval​(int pollInterval)
    Interval to poll for completed threads when threadCount or threadsPerProcessor is specified. Integer in milliseconds.; optional
    Parameters:
      `pollInterval` - New value of property pollInterval.

  - ### setFailOnAny

    public void setFailOnAny​(boolean failOnAny)
    Control whether a failure in a nested task halts execution. Note that the task will complete but existing threads will continue to run - they are not stopped
    Parameters:
      `failOnAny` - if true any nested task failure causes parallel to complete.

  - ### addTask

    public void addTask​(Task nestedTask)
    Add a nested task to execute in parallel.
    Specified by:
      `addTask` in interface `TaskContainer`
    Parameters:
      `nestedTask` - Nested task to be executed in parallel

  - ### setThreadsPerProcessor

    public void setThreadsPerProcessor​(int numThreadsPerProcessor)
    Dynamically generates the number of threads to execute based on the number of available processors (via `java.lang.Runtime.availableProcessors()`). Will overwrite the value set in threadCount; optional
    Parameters:
      `numThreadsPerProcessor` - Number of threads to create per available processor.

  - ### setThreadCount

    public void setThreadCount​(int numThreads)
    Statically determine the maximum number of tasks to execute simultaneously. If there are less tasks than threads then all will be executed at once, if there are more then only `threadCount` tasks will be executed at one time. If `threadsPerProcessor` is set then this value is ignored.; optional
    Parameters:
      `numThreads` - total number of threads.

  - ### setTimeout

    public void setTimeout​(long timeout)
    Sets the timeout on this set of tasks. If the timeout is reached before the other threads complete, the execution of this task completes with an exception. Note that existing threads continue to run.
    Parameters:
      `timeout` - timeout in milliseconds.

  - ### execute

    public void execute() throws BuildException
    Execute the parallel tasks
    Overrides:
      `execute` in class `Task`
    Throws:
      `BuildException` - if any of the threads failed.