org.apache.tools.ant.taskdefs

Class Parallel

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

UNKNOWN: category="control"

Nested Class Summary
static classParallel.TaskList
Class which holds a list of tasks to execute
Method Summary
voidaddDaemons(Parallel.TaskList daemonTasks)
Add a group of daemon threads
voidaddTask(Task nestedTask)
Add a nested task to execute in parallel.
voidexecute()
Execute the parallel tasks
voidsetFailOnAny(boolean failOnAny)
Control whether a failure in a nested task halts execution.
voidsetPollInterval(int pollInterval)
Interval to poll for completed threads when threadCount or threadsPerProcessor is specified.
voidsetThreadCount(int numThreads)
Statically determine the maximum number of tasks to execute simultaneously.
voidsetThreadsPerProcessor(int numThreadsPerProcessor)
Dynamically generates the number of threads to execute based on the number of available processors (via java.lang.Runtime.availableProcessors()).
voidsetTimeout(long timeout)
Sets the timeout on this set of tasks.

Method Detail

addDaemons

public void addDaemons(Parallel.TaskList daemonTasks)
Add a group of daemon threads

Parameters: daemonTasks The tasks to be executed as daemon.

addTask

public void addTask(Task nestedTask)
Add a nested task to execute in parallel.

Parameters: nestedTask Nested task to be executed in parallel

execute

public void execute()
Execute the parallel tasks

Throws: BuildException if any of the threads failed.

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.

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.

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 and the JVM is at least a 1.4 VM then this value is ignored.; optional

Parameters: numThreads total number of threads.

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()). Requires a J2SE 1.4 VM, and it will overwrite the value set in threadCount. If used in a 1.1, 1.2, or 1.3 VM then the task will defer to threadCount.; optional

Parameters: numThreadsPerProcessor Number of threads to create per available processor.

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.

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