C Waiting for all threads to complete

Question

I m running into a common pattern in the code that I m writing  where I need to wait for all threads in a group to complete  with a timeout  The timeout is supposed to be the time required for all threads to complete  so simply doing thread Join timeout  for each thread won t work  since the possible timeout is then timeout   numThreads   Right now I do something like the following   var threadFinishEvents   new List lt EventWaitHandle gt      foreach  DataObject data in dataList           Create local variables for the thread delegate     var threadFinish   new EventWaitHandle false  EventResetMode ManualReset       threadFinishEvents Add threadFinish        var localData    DataObject  data Clone        var thread   new Thread          delegate                         DoThreadStuff localData               threadFinish Set                         thread Start       Mutex WaitAll threadFinishEvents ToArray    timeout     However  it seems like there should be a simpler idiom for this sort of thing

User · Answer

Off the top of my head  why don t you just Thread Join timeout  and remove the time it took to join from the total timeout      pseudo-c    TimeSpan timeout   timeoutPerThread   threads Count     foreach  Thread thread in threads        DateTime start   DateTime Now       if   thread Join timeout           throw new TimeoutException         timeout -   DateTime Now - start       Edit  code is now less pseudo  don t understand why you would mod an answer -2 when the answer you modded  4 is exactly the same  only less detailed

User · Answer

I was tying to figure out how to do this but i could not get any answers from google  I know this is an old thread but here was my solution   Use the following class   class ThreadWaiter               private int  numThreads   0          private int  spinTime           public ThreadWaiter int SpinTime                        this  spinTime   SpinTime                     public void AddThreads int numThreads                         numThreads    numThreads                     public void RemoveThread                         if   numThreads  gt  0                                 numThreads--                                   public void Wait                         while   numThreads    0                                System Threading Thread Sleep  spinTime                                    Call Addthreads int numThreads  before executing a thread s   Call RemoveThread   after each one has completed  Use Wait   at the point that you want to wait for all the threads to complete before continuing

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Possible solution   var tasks   dataList      Select data   gt  Task Factory StartNew arg   gt  DoThreadStuff data   TaskContinuationOptions LongRunning   TaskContinuationOptions PreferFairness        ToArray     var timeout   TimeSpan FromMinutes 1   Task WaitAll tasks  timeout     Assuming dataList is the list of items and each item needs to be processed in a separate thread

User · Answer

With  NET 4 0 I find System Threading Tasks a lot easier to work with  Here s spin-wait loop which works reliably for me  It blocks the main thread until all the tasks complete  There s also Task WaitAll  but that hasn t always worked for me           for  int i   0  i  lt  N  i                          tasks i    Task Factory StartNew      gt                                                DoThreadStuff localData                                     while  tasks Any t   gt   t IsCompleted         spin wait

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I was tying to figure out how to do this but i could not get any answers from google  I know this is an old thread but here was my solution   Use the following class   class ThreadWaiter               private int  numThreads   0          private int  spinTime           public ThreadWaiter int SpinTime                        this  spinTime   SpinTime                     public void AddThreads int numThreads                         numThreads    numThreads                     public void RemoveThread                         if   numThreads  gt  0                                 numThreads--                                   public void Wait                         while   numThreads    0                                System Threading Thread Sleep  spinTime                                    Call Addthreads int numThreads  before executing a thread s   Call RemoveThread   after each one has completed  Use Wait   at the point that you want to wait for all the threads to complete before continuing

User · Answer

This doesn t answer the question  no timeout   but I ve made a very simple extension method to wait all threads of a collection   using System Collections Generic  using System Threading  namespace Extensions       public static class ThreadExtension               public static void WaitAll this IEnumerable lt Thread gt  threads                        if threads  null                                foreach Thread thread in threads                    thread Join                                        Then you simply call   List lt Thread gt  threads new List lt Thread gt       Add your threads to this collection threads WaitAll

User · Answer

Off the top of my head  why don t you just Thread Join timeout  and remove the time it took to join from the total timeout      pseudo-c    TimeSpan timeout   timeoutPerThread   threads Count     foreach  Thread thread in threads        DateTime start   DateTime Now       if   thread Join timeout           throw new TimeoutException         timeout -   DateTime Now - start       Edit  code is now less pseudo  don t understand why you would mod an answer -2 when the answer you modded  4 is exactly the same  only less detailed

User · Answer

This may not be an option for you  but if you can use the Parallel Extension for  NET then you could use Tasks instead of raw threads and then use Task WaitAll   to wait for them to complete

User · Answer

I still think using Join is simpler  Record the expected completion time  as Now timeout   then  in a loop  do   if  thread Join End-now       throw new NotFinishedInTime

User · Answer

With  NET 4 0 I find System Threading Tasks a lot easier to work with  Here s spin-wait loop which works reliably for me  It blocks the main thread until all the tasks complete  There s also Task WaitAll  but that hasn t always worked for me           for  int i   0  i  lt  N  i                          tasks i    Task Factory StartNew      gt                                                DoThreadStuff localData                                     while  tasks Any t   gt   t IsCompleted         spin wait

User · Answer

Since the question got bumped I will go ahead and post my solution   using  var finished   new CountdownEvent 1         for  DataObject data in dataList              finished AddCount        var localData    DataObject data Clone         var thread   new Thread           delegate                        try                         DoThreadStuff localData                threadFinish Set                          finally                         finished Signal                                       thread Start             finished Signal       finished Wait YOUR TIMEOUT

User · Answer

This may not be an option for you  but if you can use the Parallel Extension for  NET then you could use Tasks instead of raw threads and then use Task WaitAll   to wait for them to complete

User · Answer

I still think using Join is simpler  Record the expected completion time  as Now timeout   then  in a loop  do   if  thread Join End-now       throw new NotFinishedInTime

User · Answer

Off the top of my head  why don t you just Thread Join timeout  and remove the time it took to join from the total timeout      pseudo-c    TimeSpan timeout   timeoutPerThread   threads Count     foreach  Thread thread in threads        DateTime start   DateTime Now       if   thread Join timeout           throw new TimeoutException         timeout -   DateTime Now - start       Edit  code is now less pseudo  don t understand why you would mod an answer -2 when the answer you modded  4 is exactly the same  only less detailed

User · Answer

This doesn t answer the question  no timeout   but I ve made a very simple extension method to wait all threads of a collection   using System Collections Generic  using System Threading  namespace Extensions       public static class ThreadExtension               public static void WaitAll this IEnumerable lt Thread gt  threads                        if threads  null                                foreach Thread thread in threads                    thread Join                                        Then you simply call   List lt Thread gt  threads new List lt Thread gt       Add your threads to this collection threads WaitAll

User · Answer

Possible solution   var tasks   dataList      Select data   gt  Task Factory StartNew arg   gt  DoThreadStuff data   TaskContinuationOptions LongRunning   TaskContinuationOptions PreferFairness        ToArray     var timeout   TimeSpan FromMinutes 1   Task WaitAll tasks  timeout     Assuming dataList is the list of items and each item needs to be processed in a separate thread

User · Answer

This may not be an option for you  but if you can use the Parallel Extension for  NET then you could use Tasks instead of raw threads and then use Task WaitAll   to wait for them to complete

User · Answer

I still think using Join is simpler  Record the expected completion time  as Now timeout   then  in a loop  do   if  thread Join End-now       throw new NotFinishedInTime

User · Answer

I read the book C  4 0  The Complete Reference of Herbert Schildt  The author use join to give a solution           class MyThread               public int Count          public Thread Thrd          public MyThread string name                        Count   0              Thrd   new Thread this Run               Thrd Name   name              Thrd Start                         Entry point of thread          void Run                         Console WriteLine Thrd Name     starting                 do                               Thread Sleep 500                   Console WriteLine  In     Thrd Name                      Count is     Count                   Count                  while  Count  lt  10               Console WriteLine Thrd Name     terminating                            Use Join   to wait for threads to end      class JoinThreads               static void Main                         Console WriteLine  Main thread starting                    Construct three threads              MyThread mt1   new MyThread  Child  1                MyThread mt2   new MyThread  Child  2                MyThread mt3   new MyThread  Child  3                mt1 Thrd Join                Console WriteLine  Child  1 joined                 mt2 Thrd Join                Console WriteLine  Child  2 joined                 mt3 Thrd Join                Console WriteLine  Child  3 joined                 Console WriteLine  Main thread ending                 Console ReadKey

User · Answer

I still think using Join is simpler  Record the expected completion time  as Now timeout   then  in a loop  do   if  thread Join End-now       throw new NotFinishedInTime

User · Answer

Off the top of my head  why don t you just Thread Join timeout  and remove the time it took to join from the total timeout      pseudo-c    TimeSpan timeout   timeoutPerThread   threads Count     foreach  Thread thread in threads        DateTime start   DateTime Now       if   thread Join timeout           throw new TimeoutException         timeout -   DateTime Now - start       Edit  code is now less pseudo  don t understand why you would mod an answer -2 when the answer you modded  4 is exactly the same  only less detailed

User · Answer

This may not be an option for you  but if you can use the Parallel Extension for  NET then you could use Tasks instead of raw threads and then use Task WaitAll   to wait for them to complete

User · Answer

I read the book C  4 0  The Complete Reference of Herbert Schildt  The author use join to give a solution           class MyThread               public int Count          public Thread Thrd          public MyThread string name                        Count   0              Thrd   new Thread this Run               Thrd Name   name              Thrd Start                         Entry point of thread          void Run                         Console WriteLine Thrd Name     starting                 do                               Thread Sleep 500                   Console WriteLine  In     Thrd Name                      Count is     Count                   Count                  while  Count  lt  10               Console WriteLine Thrd Name     terminating                            Use Join   to wait for threads to end      class JoinThreads               static void Main                         Console WriteLine  Main thread starting                    Construct three threads              MyThread mt1   new MyThread  Child  1                MyThread mt2   new MyThread  Child  2                MyThread mt3   new MyThread  Child  3                mt1 Thrd Join                Console WriteLine  Child  1 joined                 mt2 Thrd Join                Console WriteLine  Child  2 joined                 mt3 Thrd Join                Console WriteLine  Child  3 joined                 Console WriteLine  Main thread ending                 Console ReadKey

User · Answer

Since the question got bumped I will go ahead and post my solution   using  var finished   new CountdownEvent 1         for  DataObject data in dataList              finished AddCount        var localData    DataObject data Clone         var thread   new Thread           delegate                        try                         DoThreadStuff localData                threadFinish Set                          finally                         finished Signal                                       thread Start             finished Signal       finished Wait YOUR TIMEOUT

[c#] C#: Waiting for all threads to complete

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