Package org.eclipse.jetty.util.thread

Class QueuedThreadPool

java.lang.Object
org.eclipse.jetty.util.component.AbstractLifeCycle
org.eclipse.jetty.util.component.ContainerLifeCycle
org.eclipse.jetty.util.thread.QueuedThreadPool
All Implemented Interfaces:
Executor, ThreadFactory, Container, Destroyable, Dumpable, Dumpable.DumpableContainer, LifeCycle, ThreadPool, ThreadPool.SizedThreadPool, TryExecutor, VirtualThreads.Configurable
Direct Known Subclasses:
MonitoredQueuedThreadPool
@ManagedObject("A thread pool") public class QueuedThreadPool extends ContainerLifeCycle implements ThreadFactory, ThreadPool.SizedThreadPool, Dumpable, TryExecutor, VirtualThreads.Configurable

A thread pool with a queue of jobs to execute.

Jetty components that need threads (such as network acceptors and selector) may lease threads from this thread pool using a ThreadPoolBudget; these threads are "active" from the point of view of the thread pool, but not available to run transient jobs such as processing an HTTP request or a WebSocket frame.

QueuedThreadPool has a ReservedThreadExecutor which leases threads from this pool, but makes them available as if they are "idle" threads.

QueuedThreadPool therefore has the following fundamental values:

  • threads: the current number of threads. These threads may execute a job (either internal or transient), or may be ready to run (either idle or reserved). This number may grow or shrink as the thread pool grows or shrinks.
  • readyThreads: the current number of threads that are ready to run transient jobs. This number may grow or shrink as the thread pool grows or shrinks.
  • leasedThreads: the number of threads that run internal jobs. This number is typically constant after this thread pool is started.

Given the definitions above, the most interesting definitions are:

Other definitions, typically less interesting because they take into account threads that execute internal jobs, or because they don't take into account available reserved threads (that are essentially ready to execute transient jobs), are:

  • Constructor Details

    • QueuedThreadPool

      public QueuedThreadPool()

    • QueuedThreadPool

      public QueuedThreadPool(@Name("maxThreads") int maxThreads)

    • QueuedThreadPool

      public QueuedThreadPool(@Name("maxThreads") int maxThreads, @Name("minThreads") int minThreads)

    • QueuedThreadPool

      public QueuedThreadPool(@Name("maxThreads") int maxThreads, @Name("minThreads") int minThreads, @Name("queue") BlockingQueue<Runnable> queue)

    • QueuedThreadPool

      public QueuedThreadPool(@Name("maxThreads") int maxThreads, @Name("minThreads") int minThreads, @Name("idleTimeout") int idleTimeout)

    • QueuedThreadPool

      public QueuedThreadPool(@Name("maxThreads") int maxThreads, @Name("minThreads") int minThreads, @Name("idleTimeout") int idleTimeout, @Name("queue") BlockingQueue<Runnable> queue)

    • QueuedThreadPool

      public QueuedThreadPool(@Name("maxThreads") int maxThreads, @Name("minThreads") int minThreads, @Name("idleTimeout") int idleTimeout, @Name("queue") BlockingQueue<Runnable> queue, @Name("threadGroup") ThreadGroup threadGroup)

    • QueuedThreadPool

      public QueuedThreadPool(@Name("maxThreads") int maxThreads, @Name("minThreads") int minThreads, @Name("idleTimeout") int idleTimeout, @Name("reservedThreads") int reservedThreads, @Name("queue") BlockingQueue<Runnable> queue, @Name("threadGroup") ThreadGroup threadGroup)

    • QueuedThreadPool

      public QueuedThreadPool(@Name("maxThreads") int maxThreads, @Name("minThreads") int minThreads, @Name("idleTimeout") int idleTimeout, @Name("reservedThreads") int reservedThreads, @Name("queue") BlockingQueue<Runnable> queue, @Name("threadGroup") ThreadGroup threadGroup, @Name("threadFactory") ThreadFactory threadFactory)

  • Method Details

    • getThreadPoolBudget

      public ThreadPoolBudget getThreadPoolBudget()
      Specified by:
      getThreadPoolBudget in interface ThreadPool.SizedThreadPool
      Returns:
      a ThreadPoolBudget for this sized thread pool, or null of no ThreadPoolBudget can be returned

    • setThreadPoolBudget

      public void setThreadPoolBudget(ThreadPoolBudget budget)

    • setStopTimeout

      public void setStopTimeout(long stopTimeout)

    • getStopTimeout

      public long getStopTimeout()

    • doStart

      protected void doStart() throws Exception
      Description copied from class: ContainerLifeCycle
      Starts the managed lifecycle beans in the order they were added.
      Overrides:
      doStart in class ContainerLifeCycle
      Throws:
      AbstractLifeCycle.StopException - If thrown, the lifecycle will immediately be stopped.
      Exception - If there was a problem starting. Will cause a transition to FAILED state

    • doStop

      protected void doStop() throws Exception
      Description copied from class: ContainerLifeCycle
      Stops the managed lifecycle beans in the reverse order they were added.
      Overrides:
      doStop in class ContainerLifeCycle
      Throws:
      Exception - If there was a problem stopping. Will cause a transition to FAILED state

    • getIdleTimeout

      @ManagedAttribute("maximum time a thread may be idle in ms") public int getIdleTimeout()
      Returns:
      the maximum thread idle time in ms

    • setIdleTimeout

      public void setIdleTimeout(int idleTimeout)

      Set the maximum thread idle time in ms.

      Threads that are idle for longer than this period may be stopped.

      Parameters:
      idleTimeout - the maximum thread idle time in ms

    • getMaxThreads

      @ManagedAttribute("maximum number of threads in the pool") public int getMaxThreads()
      Specified by:
      getMaxThreads in interface ThreadPool.SizedThreadPool
      Returns:
      the maximum number of threads

    • setMaxThreads

      public void setMaxThreads(int maxThreads)
      Specified by:
      setMaxThreads in interface ThreadPool.SizedThreadPool
      Parameters:
      maxThreads - the maximum number of threads

    • getMinThreads

      @ManagedAttribute("minimum number of threads in the pool") public int getMinThreads()
      Specified by:
      getMinThreads in interface ThreadPool.SizedThreadPool
      Returns:
      the minimum number of threads

    • setMinThreads

      public void setMinThreads(int minThreads)
      Specified by:
      setMinThreads in interface ThreadPool.SizedThreadPool
      Parameters:
      minThreads - minimum number of threads

    • getReservedThreads

      @ManagedAttribute("number of configured reserved threads or -1 for heuristic") public int getReservedThreads()
      Returns:
      number of reserved threads or -1 for heuristically determined

    • setReservedThreads

      public void setReservedThreads(int reservedThreads)
      Parameters:
      reservedThreads - number of reserved threads or -1 for heuristically determined

    • getName

      @ManagedAttribute("name of the thread pool") public String getName()
      Returns:
      the name of the this thread pool

    • setName

      public void setName(String name)

      Sets the name of this thread pool, used as a prefix for the thread names.

      Parameters:
      name - the name of the this thread pool

    • getThreadsPriority

      @ManagedAttribute("priority of threads in the pool") public int getThreadsPriority()
      Returns:
      the priority of the pool threads

    • setThreadsPriority

      public void setThreadsPriority(int priority)
      Parameters:
      priority - the priority of the pool threads

    • isDaemon

      @ManagedAttribute("thread pool uses daemon threads") public boolean isDaemon()
      Returns:
      whether to use daemon threads
      See Also:

    • setDaemon

      public void setDaemon(boolean daemon)
      Parameters:
      daemon - whether to use daemon threads
      See Also:

    • isDetailedDump

      @ManagedAttribute("reports additional details in the dump") public boolean isDetailedDump()

    • setDetailedDump

      public void setDetailedDump(boolean detailedDump)

    • getLowThreadsThreshold

      @ManagedAttribute("threshold at which the pool is low on threads") public int getLowThreadsThreshold()

    • setLowThreadsThreshold

      public void setLowThreadsThreshold(int lowThreadsThreshold)

    • getVirtualThreadsExecutor

      public Executor getVirtualThreadsExecutor()
      Specified by:
      getVirtualThreadsExecutor in interface VirtualThreads.Configurable
      Returns:
      the Executor to use to execute tasks in virtual threads

    • setVirtualThreadsExecutor

      public void setVirtualThreadsExecutor(Executor executor)
      Specified by:
      setVirtualThreadsExecutor in interface VirtualThreads.Configurable
      Parameters:
      executor - the Executor to use to execute tasks in virtual threads
      See Also:

    • setMaxEvictCount

      public void setMaxEvictCount(int evictCount)

      Returns the maximum number of idle threads that are evicted for every idle timeout period, thus shrinking this thread pool towards its minimum number of threads. The default value is 1.

      For example, consider a thread pool with minThread=2, maxThread=20, idleTimeout=5000 and maxEvictCount=3. Let's assume all 20 threads are executing a task, and they all finish their own tasks at the same time and no more tasks are submitted; then, 3 threads will be evicted, while the other 17 will wait another idle timeout; then another 3 threads will be evicted, and so on until minThreads=2 will be reached.

      Parameters:
      evictCount - the maximum number of idle threads to evict in one idle timeout period

    • getMaxEvictCount

      @ManagedAttribute("maximum number of idle threads to evict in one idle timeout period") public int getMaxEvictCount()
      Returns:
      the maximum number of idle threads to evict in one idle timeout period

    • getQueueSize

      @ManagedAttribute("size of the job queue") public int getQueueSize()
      Returns:
      the number of jobs in the queue waiting for a thread

    • getMaxReservedThreads

      @ManagedAttribute("maximum number (capacity) of reserved threads") public int getMaxReservedThreads()
      Returns:
      the maximum number (capacity) of reserved threads
      See Also:

    • getAvailableReservedThreads

      @ManagedAttribute("number of available reserved threads") public int getAvailableReservedThreads()
      Returns:
      the number of available reserved threads
      See Also:

    • getThreads

      @ManagedAttribute("number of threads in the pool") public int getThreads()

      The fundamental value that represents the number of threads currently known by this thread pool.

      This value includes threads that have been leased to internal components, idle threads, reserved threads and threads that are executing transient jobs.

      Specified by:
      getThreads in interface ThreadPool
      Returns:
      the number of threads currently known to the pool
      See Also:

    • getReadyThreads

      @ManagedAttribute("number of threads ready to execute transient jobs") public int getReadyThreads()

      The fundamental value that represents the number of threads ready to execute transient jobs.

      Returns:
      the number of threads ready to execute transient jobs
      See Also:

    • getLeasedThreads

      @ManagedAttribute("number of threads used by internal components") public int getLeasedThreads()

      The fundamental value that represents the number of threads that are leased to internal components, and therefore cannot be used to execute transient jobs.

      Returns:
      the number of threads currently used by internal components
      See Also:

    • getMaxLeasedThreads

      @ManagedAttribute("maximum number of threads leased to internal components") public int getMaxLeasedThreads()

      The maximum number of threads that are leased to internal components, as some component may allocate its threads lazily.

      Returns:
      the maximum number of threads leased by internal components
      See Also:

    • getIdleThreads

      @ManagedAttribute("number of idle threads but not reserved") public int getIdleThreads()

      The number of idle threads, but without including reserved threads.

      Prefer getReadyThreads() for a better representation of "threads ready to execute transient jobs".

      Specified by:
      getIdleThreads in interface ThreadPool
      Returns:
      the number of idle threads but not reserved
      See Also:

    • getBusyThreads

      @ManagedAttribute("number of threads executing internal and transient jobs") public int getBusyThreads()

      The number of threads executing internal and transient jobs.

      Prefer getUtilizedThreads() for a better representation of "threads executing transient jobs".

      Returns:
      the number of threads executing internal and transient jobs
      See Also:

    • getUtilizedThreads

      @ManagedAttribute("number of threads executing transient jobs") public int getUtilizedThreads()

      The number of threads executing transient jobs.

      Returns:
      the number of threads executing transient jobs
      See Also:

    • getMaxAvailableThreads

      @ManagedAttribute("maximum number of threads available to run transient jobs") public int getMaxAvailableThreads()

      The maximum number of threads available to run transient jobs.

      Returns:
      the maximum number of threads available to run transient jobs

    • getUtilizationRate

      @ManagedAttribute("utilization rate of threads executing transient jobs") public double getUtilizationRate()

      The rate between the number of utilized threads and the maximum number of utilizable threads.

      A value of 0.0D means that the thread pool is not utilized, while a value of 1.0D means that the thread pool is fully utilized to execute transient jobs.

      Returns:
      the utilization rate of threads executing transient jobs

    • isLowOnThreads

      @ManagedAttribute(value="thread pool is low on threads", readonly=true) public boolean isLowOnThreads()

      Returns whether this thread pool is low on threads.

      The current formula is:

       maxThreads - threads + readyThreads - queueSize <= lowThreadsThreshold
      Specified by:
      isLowOnThreads in interface ThreadPool
      Returns:
      whether the pool is low on threads
      See Also:

    • execute

      public void execute(Runnable job)
      Specified by:
      execute in interface Executor
      Specified by:
      execute in interface TryExecutor

    • tryExecute

      public boolean tryExecute(Runnable task)
      Description copied from interface: TryExecutor
      Attempt to execute a task.
      Specified by:
      tryExecute in interface TryExecutor
      Parameters:
      task - The task to be executed
      Returns:
      True IFF the task has been given directly to a thread to execute. The task cannot be queued pending the later availability of a Thread.

    • join

      public void join() throws InterruptedException
      Blocks until the thread pool is LifeCycle stopped.
      Specified by:
      join in interface ThreadPool
      Throws:
      InterruptedException - if thread was interrupted

    • startThread

      protected void startThread()

    • newThread

      public Thread newThread(Runnable runnable)
      Specified by:
      newThread in interface ThreadFactory

    • removeThread

      protected void removeThread(Thread thread)

    • dump

      public void dump(Appendable out, String indent) throws IOException
      Description copied from interface: Dumpable
      Dump this object (and children) into an Appendable using the provided indent after any new lines. The indent should not be applied to the first object dumped.
      Specified by:
      dump in interface Dumpable
      Overrides:
      dump in class ContainerLifeCycle
      Parameters:
      out - The appendable to dump to
      indent - The indent to apply after any new lines.
      Throws:
      IOException - if unable to write to Appendable

    • runJob

      protected void runJob(Runnable job)

      Runs the given job in the current thread.

      Subclasses may override to perform pre/post actions before/after the job is run.

      Parameters:
      job - the job to run

    • evict

      protected boolean evict()

      Determines whether to evict the current thread from the pool.

      Returns:
      whether the current thread should be evicted

    • getQueue

      protected BlockingQueue<Runnable> getQueue()
      Returns:
      the job queue

    • interruptThread

      @ManagedOperation("interrupts a pool thread") public boolean interruptThread(@Name("id") long id)
      Parameters:
      id - the thread ID to interrupt.
      Returns:
      true if the thread was found and interrupted.

    • dumpThread

      @ManagedOperation("dumps a pool thread stack") public String dumpThread(@Name("id") long id)
      Parameters:
      id - the thread ID to interrupt.
      Returns:
      the stack frames dump

    • toString

      public String toString()
      Overrides:
      toString in class AbstractLifeCycle