CODEWITHSUNDEEP
c++multithreadingconcurrencyc++14boost-asio
Ehsan Sharifi Esfahani
Ehsan Sharifi Esfahani

Reputation: 23

Can I block a thread and its children in C++

I have a code like this

Create thread_1 and bind task 1 to that;
Create thread_2 and bind task 2 to that;
Create thread_3 and it monitors the keyboards and work as follow:
     while(true){
       get the next key;
       if (the next key == 'p')
            pause_the_code();
       if (the next key == 'r')
            resume_the_code();
       if(the next key == 'q'
            exit the while loop
      }
// can I here block the Thread_1 and _Thread_2 with all of their children 
//with wait() when I call pause_the_code(); or notify them when I call resume_the_code();

Please note that hread_1 and Thread_2 each one can dynamically create different bunch of threads.

Upvotes: 0

Views: 191

Answers (1)

Zan Lynx
Zan Lynx

Reputation: 54325

No you cannot reach out from one thread and pause or block another thread. Not in any safe way.

What you do is create a way for the threads to block themselves, by checking for it.

  • You could use an atomic boolean variable named something like running and when it was false run a small loop with a sleep in it.

  • You could use a condition variable and a mutex protecting a boolean named running and when it was false wait for a condition notification.

  • You could have each worker thread lock on a mutex. If thread_3 holds the mutex instead, they cannot take it and must wait until it is released.

Upvotes: 2

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