Naming threads and thread-pools of ExecutorService

Question

Let s say I have an application that utilizes the Executor framework as such  Executors newSingleThreadExecutor   submit new Runnable         Override     public void run               do stuff           When I run this application in the debugger  a thread is created with the following  default  name  Thread pool-1-thread-1   As you can see  this isn t terribly useful and as far as I can tell  the Executor framework does not provide an easy way to name the created threads or thread-pools   So  how does one go about providing names for the threads thread-pools  For instance  Thread FooPool-FooThread

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Executors newSingleThreadExecutor r - gt  new Thread r   someName    submit getJob      Runnable getJob             return    - gt                   your job

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Using the existing functionality of Executors defaultThreadFactory   but just setting the name  import java util concurrent Executors  import java util concurrent ThreadFactory   public class NamingThreadFactory implements ThreadFactory       private final String prefix      private int threadNuber   0       public NamingThreadFactory String prefix           this prefix   prefix              Override     public Thread newThread Runnable r            Thread t   Executors defaultThreadFactory   newThread r           t setName prefix   threadNuber           return t

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Thought I d throw in some simplified examples  just so the options are all out there  Unique number  could also put this into a method   AtomicInteger threadNum   new AtomicInteger 0   ExecutorService e   Executors newSingleThreadExecutor r - gt  new Thread r   quot my-name- quot    threadNum incrementAndGet       Unique number and  quot probably quot  unique name  if you re generating new Runnable objects    Useful if starting off the threads is within a method that gets called more than once  for instance  AtomicInteger threadNum   new AtomicInteger 0   ExecutorService e   Executors newSingleThreadExecutor r - gt  new Thread r   quot my-name- quot    threadNum incrementAndGet      quot - quot    r hashCode       If you really wanted a unique name each time you d need a class with a static var  and could also add a static pool number prefix in there as well  see other answers   and an equivalent in JDK  lt  8  you don t need a new class for it  or could return a ThreadFactory out of a method   Executors newSingleThreadExecutor new ThreadFactory           AtomicInteger threadCount   new AtomicInteger 0           Override       public Thread newThread Runnable r            return new Thread r   quot your-name- quot    threadCount getAndIncrement      quot - quot    r hashCode        could also use Integer toHexString r hashCode    for shorter                   And could make that into a method for the  quot you-name- quot  aspect as a variable   Or use a separate class with a constructor like the other answers all seem to

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The BasicThreadFactory from apache commons-lang is also useful to provide the naming behavior  Instead of writing an anonymous inner class  you can use the Builder to name the threads as you want  Here s the example from the javadocs       Create a factory that produces daemon threads with a naming pattern and     a priority  BasicThreadFactory factory   new BasicThreadFactory Builder         namingPattern  workerthread- d         daemon true        priority Thread MAX PRIORITY        build        Create an executor service for single-threaded execution  ExecutorService exec   Executors newSingleThreadExecutor factory

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I find it easiest to use a lambda as a thread factory if you just want to change the name for a single thread executor   Executors newSingleThreadExecutor runnable - gt  new Thread runnable   Your name

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You can write your own implementation of ThreadFactory  using for example some existing implementation  like defaultThreadFactory  and change the name at the end   Example of implementing ThreadFactory    class ThreadFactoryWithCustomName implements ThreadFactory       private final ThreadFactory threadFactory      private final String name       public ThreadFactoryWithCustomName final ThreadFactory threadFactory  final String name            this threadFactory   threadFactory          this name   name              Override     public Thread newThread final Runnable r            final Thread thread   threadFactory newThread r           thread setName name           return thread            And usage   Executors newSingleThreadExecutor new ThreadFactoryWithCustomName          Executors defaultThreadFactory             customName

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You could supply a ThreadFactory to newSingleThreadScheduledExecutor ThreadFactory threadFactory   The factory will be responsibe for creating threads  and will be able to name them  To quote the Javadoc   Creating new threads New threads are created using a ThreadFactory  If not otherwise specified  a Executors defaultThreadFactory   is used  that creates threads to all be in the same ThreadGroup and with the same NORM PRIORITY priority and non-daemon status  By supplying a different ThreadFactory  you can alter the thread s name  thread group  priority  daemon status  etc  If a ThreadFactory fails to create a thread when asked by returning null from newThread  the executor will continue  but might not be able to execute any tasks

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If you are using Spring  there is CustomizableThreadFactory for which you can set a thread name prefix   Example   ExecutorService alphaExecutor       Executors newFixedThreadPool 10  new CustomizableThreadFactory  alpha-       Alternatively  you can create your ExecutorService as a Spring bean using ThreadPoolExecutorFactoryBean - then the threads will all be named with the beanName- prefix    Bean public ThreadPoolExecutorFactoryBean myExecutor         ThreadPoolExecutorFactoryBean executorFactoryBean   new ThreadPoolExecutorFactoryBean           configuration of your choice     return executorFactoryBean      In the example above  the threads will be named with myExecutor- prefix  You can set the prefix explicitly to a different value  eg   myPool-   by setting executorFactoryBean setThreadNamePrefix  myPool-   on the factory bean

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There s an open RFE for this with Oracle  From the comments from the Oracle employee it seems they don t understand the issue and won t fix  It s one of these things that is dead simple to support in the JDK  without breaking backwards compatibility  so it is kind of a shame that the RFE gets misunderstood   As pointed out you need to implement your own ThreadFactory  If you don t want to pull in Guava or Apache Commons just for this purpose I provide here a ThreadFactory implementation that you can use  It is exactly similar to what you get from the JDK except for the ability to set the thread name prefix to something else than  pool    package org demo concurrency   import java util concurrent ThreadFactory  import java util concurrent atomic AtomicInteger          ThreadFactory with the ability to set the thread name prefix      This class is exactly similar to       link java util concurrent Executors defaultThreadFactory       from JDK8  except for the thread naming feature         lt p gt     The factory creates threads that have names on the form     lt i gt prefix-N-thread-M lt  i gt   where  lt i gt prefix lt  i gt     is a string provided in the constructor   lt i gt N lt  i gt  is the sequence number of    this factory  and  lt i gt M lt  i gt  is the sequence number of the thread created     by this factory      public class ThreadFactoryWithNamePrefix implements ThreadFactory           Note   The source code for this class was based entirely on         Executors DefaultThreadFactory class from the JDK8 source         The only change made is the ability to configure the thread        name prefix        private static final AtomicInteger poolNumber   new AtomicInteger 1       private final ThreadGroup group      private final AtomicInteger threadNumber   new AtomicInteger 1       private final String namePrefix                  Creates a new ThreadFactory where threads are created with a name prefix        of  lt code gt prefix lt  code gt                  param prefix Thread name prefix  Never use a value of  pool  as in that             case you might as well have used               link java util concurrent Executors defaultThreadFactory                 public ThreadFactoryWithNamePrefix String prefix            SecurityManager s   System getSecurityManager            group    s    null    s getThreadGroup                     Thread currentThread   getThreadGroup            namePrefix   prefix    -                    poolNumber getAndIncrement                      -thread-                Override     public Thread newThread Runnable r            Thread t   new Thread group  r                  namePrefix   threadNumber getAndIncrement                    0           if  t isDaemon                  t setDaemon false                     if  t getPriority      Thread NORM PRIORITY                t setPriority Thread NORM PRIORITY                     return t            When you want to use it you simply take advantage of the fact that all Executors methods allow you to provide your own ThreadFactory    This      Executors newSingleThreadExecutor      will give an ExecutorService where threads are named pool-N-thread-M but by using       Executors newSingleThreadExecutor new ThreadFactoryWithNamePrefix  primecalc       you ll get an ExecutorService where threads are named primecalc-N-thread-M  Voila

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The home-grown core Java solution that I use to decorate existing factories   public class ThreadFactoryNameDecorator implements ThreadFactory       private final ThreadFactory defaultThreadFactory      private final String suffix       public ThreadFactoryNameDecorator String suffix            this Executors defaultThreadFactory    suffix              public ThreadFactoryNameDecorator ThreadFactory threadFactory  String suffix            this defaultThreadFactory   threadFactory          this suffix   suffix              Override     public Thread newThread Runnable task            Thread thread   defaultThreadFactory newThread task           thread setName thread getName      -    suffix           return thread            In action   Executors newSingleThreadExecutor new ThreadFactoryNameDecorator  foo

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You can also change the name of your thread afterwards  while the thread is executed   Thread currentThread   setName  FooName      That could be of interest if for instance you re using the same ThreadFactory for different type of tasks

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As other answers already said  you may create and use your own implementation of the java util concurrent ThreadFactory interface  no external libraries required   I am pasting my code below because it is different than previous answers since it uses String format method and takes a base name for the threads as a constructor argument   import java util concurrent ThreadFactory   public class NameableThreadFactory implements ThreadFactory      private int threadsNum      private final String namePattern       public NameableThreadFactory String baseName           namePattern   baseName    - d               Override     public Thread newThread Runnable runnable           threadsNum            return new Thread runnable  String format namePattern  threadsNum                  And this is an example of usage   ThreadFactory  threadFactory   new NameableThreadFactory  listenerThread            final ExecutorService executorService   Executors newFixedThreadPool 5  threadFactory     EDIT  making my ThreadFactory implementation thread-safe  thanks to  mchernyakov for pointing it out  Even though nowhere in the ThreadFactory documentation is said that its implementations must be thread-safe  the fact that the DefaultThreadFactory is thread-safe is a big hint   import java util concurrent ThreadFactory  import java util concurrent atomic AtomicInteger   public class NameableThreadFactory implements ThreadFactory      private final AtomicInteger threadsNum   new AtomicInteger         private final String namePattern       public NameableThreadFactory String baseName           namePattern   baseName    - d               Override     public Thread newThread Runnable runnable           return new Thread runnable  String format namePattern  threadsNum addAndGet 1

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Extend  ThreadFactory  public interface ThreadFactory     An object that creates new threads on demand  Using thread factories removes hardwiring of calls to new Thread  enabling applications to use special thread subclasses  priorities  etc    Thread newThread Runnable r      Constructs a new Thread  Implementations may also initialize priority  name  daemon status  ThreadGroup  etc    Sample code   import java util concurrent    import java util concurrent atomic     import java util concurrent ThreadPoolExecutor DiscardPolicy   class SimpleThreadFactory implements ThreadFactory      String name     AtomicInteger threadNo   new AtomicInteger 0       public SimpleThreadFactory  String name          this name   name          public Thread newThread Runnable r         String threadName   name     threadNo incrementAndGet         System out println  threadName   threadName        return new Thread r threadName            public static void main String args             SimpleThreadFactory factory   new SimpleThreadFactory  Factory Thread            ThreadPoolExecutor executor  new ThreadPoolExecutor 1 1 60                      TimeUnit SECONDS new ArrayBlockingQueue lt Runnable gt  1  new ThreadPoolExecutor DiscardPolicy               final ExecutorService executorService   Executors newFixedThreadPool 5 factory            for   int i 0  i  lt  100  i                 executorService submit new Runnable                     public void run                        System out println  Thread Name in Runnable   Thread currentThread   getName                                                          executorService shutdown               output   java SimpleThreadFactory  thread no 1 thread no 2 Thread Name in Runnable Factory Thread 1 Thread Name in Runnable Factory Thread 2 thread no 3 thread no 4 Thread Name in Runnable Factory Thread 3 Thread Name in Runnable Factory Thread 4 thread no 5 Thread Name in Runnable Factory Thread 5       etc

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I use to do same like below  requires guava library     ThreadFactory namedThreadFactory   new ThreadFactoryBuilder   setNameFormat  SO-POOL- d   build    ExecutorService executorService   Executors newFixedThreadPool 5 namedThreadFactory

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You can try to provide your own thread factory  which will create thread with appropriate names   Here s one example   class YourThreadFactory implements ThreadFactory      public Thread newThread Runnable r         return new Thread r   Your name             Executors newSingleThreadExecutor new YourThreadFactory    submit someRunnable

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This is my customized factory providing a customized names for thread dump analyzers  Usually I just give tf null to reuse JVM default thread factory  This website has more advanced thread factory   public class SimpleThreadFactory implements ThreadFactory       private ThreadFactory tf      private String nameSuffix       public SimpleThreadFactory  ThreadFactory tf  String nameSuffix            this tf   tf  null   tf   Executors defaultThreadFactory            this nameSuffix   nameSuffix               Override public Thread newThread Runnable task               default  pool-1-thread-1  to  pool-1-thread-1-myapp-MagicTask          Thread thread tf newThread task           thread setName thread getName    -  nameSuffix           return thread           - - - - -   ExecutorService es   Executors newFixedThreadPool 4  new SimpleThreadFactory null   myapp-MagicTask        For your convenience this is a thread dump loop for debug purpose       ThreadMXBean mxBean ManagementFactory getThreadMXBean        long   tids   mxBean getAllThreadIds        System out println  ------------        System out println  ThreadCount   tids length       for long tid   tids            ThreadInfo mxInfo mxBean getThreadInfo tid           if  mxInfo  null                System out printf   d  s n   tid   Thread not found              else               System out printf   d  s  state  s  suspended  d  lockowner  d  s n                        mxInfo getThreadId    mxInfo getThreadName                         mxInfo getThreadState   toString                         mxInfo isSuspended   1 0                       mxInfo getLockOwnerId    mxInfo getLockOwnerName

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Based on few of the comments above  difference is I just used lambda Executors newFixedThreadPool 10  r - gt  new Thread r   quot my-threads- d quot

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A quick and dirty way is to use Thread currentThread   setName myName   in the run   method

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private class TaskThreadFactory implements ThreadFactory         Override     public Thread newThread Runnable r            Thread t   new Thread r   TASK EXECUTION THREAD             return t             Pass the ThreadFactory to an executorservice and you are good to go

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Guava almost always has what you need    ThreadFactory namedThreadFactory      new ThreadFactoryBuilder   setNameFormat  my-sad-thread- d   build     and pass it off to your ExecutorService

[java] Naming threads and thread-pools of ExecutorService

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