Package com.sun.jini.thread

Class TaskManager

java.lang.Object
com.sun.jini.thread.TaskManager
public class TaskManager extends Object
A task manager manages a single queue of tasks, and some number of worker threads. New tasks are added to the tail of the queue. Each thread loops, taking a task from the queue and running it. Each thread looks for a task by starting at the head of the queue and taking the first task (that is not already being worked on) that is not required to run after any of the tasks that precede it in the queue (including tasks that are currently being worked on).

This class uses the Logger named com.sun.jini.thread.TaskManager to log information at the following logging levels:

com.sun.jini.thread.TaskManager
LevelDescription
SEVERE failure to create a worker thread when no other worker threads exist
WARNING exceptions thrown by TaskManager.Task methods, and failure to create a worker thread when other worker threads exist
Author:
Sun Microsystems, Inc.

  • Field Details

    • logger

      protected static final org.slf4j.Logger logger
      Logger

    • tasks

      protected final ArrayList<TaskManager.Task> tasks
      Active and pending tasks

    • firstPending

      protected int firstPending
      Index of the first pending task; all earlier tasks are active

    • roTasks

      protected final List roTasks
      Read-only view of tasks

    • threads

      protected final List<com.sun.jini.thread.TaskManager.TaskThread> threads
      Active threads

    • maxThreads

      protected final int maxThreads
      Maximum number of threads allowed

    • timeout

      protected final long timeout
      Idle time before a thread should exit

    • loadFactor

      protected final float loadFactor
      Threshold for creating new threads

    • terminated

      protected boolean terminated
      True if manager has been terminated

  • Constructor Details

    • TaskManager

      public TaskManager()
      Create a task manager with maxThreads = 10, timeout = 15 seconds, and loadFactor = 3.0.

    • TaskManager

      public TaskManager(int maxThreads, long timeout, float loadFactor)
      Create a task manager.
      Parameters:
      maxThreads - maximum number of threads to use on tasks
      timeout - idle time before a thread exits
      loadFactor - threshold for creating new threads. A new thread is created if the total number of runnable tasks (both active and pending) exceeds the number of threads times the loadFactor, and the maximum number of threads has not been reached.

    • TaskManager

      public TaskManager(int maxThreads, long timeout, float loadFactor, String threadName, int retriesOnIdle)

    • TaskManager

      public TaskManager(int maxThreads, long timeout, float loadFactor, String threadName, int retriesOnIdle, int threadPriority)

  • Method Details

    • addIfNew

      public void addIfNew(TaskManager.Task t)
      Add a new task if it is not equal to (using the equals method) to any existing active or pending task.

    • add

      public void add(TaskManager.Task t)
      Add a new task.

    • setThreadName

      public void setThreadName(String threadName)

    • getThreadName

      public String getThreadName()

    • addAll

      public void addAll(Collection c)
      Add all tasks in a collection, in iterator order.

    • needThread

      protected boolean needThread()
      Return true if a new thread should be created (ignoring maxThreads).

    • removeIfPending

      public boolean removeIfPending(TaskManager.Task t)
      Remove a task if it is pending (not active). Object identity (==) is used, not the equals method. Returns true if the task was removed.

    • remove

      public boolean remove(TaskManager.Task t)

    • terminate

      public void terminate()
      Interrupt all threads, and stop processing tasks. Only getPending should be used afterwards.

    • isTerminated

      public boolean isTerminated()

    • getPending

      public List<TaskManager.Task> getPending()
      Return all pending tasks. A new list is returned each time.

    • getTotalTasks

      public int getTotalTasks()
      Returns the total number of tasks to be executed and currently executing.

    • getMaxThreads

      public int getMaxThreads()
      Return the maximum number of threads to use on tasks.

    • getThreadCount

      public int getThreadCount()
      Returns:
      the number of threads currently allocated (less or equal to getMaxThreads())
      Since:
      12.3

    • getRunningThreadCount

      public int getRunningThreadCount()
      Returns:
      the number of threads actively running a task
      Since:
      12.3