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:
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

  • 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.