A return statement causes a task to return immediately to its caller. A return statement causes the task to return to its caller immediately. If the execution of a task falls through to its end, an implicit return is executed. What return does not do is terminate all the child threads.

The terminate statement terminates all descendants of the process in which it was called. What terminate does is, it terminate all the child threads.

  1 #include "vera_defines.vrh"
  2 
  3 program task_terminate {
  4   task t1 () {
  5     printf("%0d Inside t1\n", get_time(LO));
  6     fork 
  7       { t2(); }
  8       { t3(); }
  9     join none
 10     delay(100);
 11     printf("%0d terminating t1 child process\n", get_time(LO));
 12     terminate;
 13     printf("%0d  afterterminate in t1\n", get_time(LO));
 14     
 15   }
 16 
 17   task t2 () {
 18     printf("%0d Inside t2\n", get_time(LO));
 19     fork 
 20       { t2_t1(); }
 21     join none
 22     delay(40);
 23     printf("%0d Returning from t2\n", get_time(LO));
 24     return;
 25   }
 26 
 27   task t3 () {
 28     while (1) {
 29       delay(5);
 30       printf("%0d from t2_t1_t1\n", get_time(LO));
 31     }
 32   }
 33 
 34   task t2_t1 () {
 35     printf("%0d Inside t2_t1\n", get_time(LO));
 36     fork 
 37       { t2_t1_t1(); }
 38     join none
 39   }
 40   
 41   task t2_t1_t1 () {
 42     while (1) {
 43       delay(4);
 44       printf("%0d from t2_t1_t1\n", get_time(LO));
 45     }
 46   }
 47 
 48   t1();
 49   delay(100);
 50   printf("%0d terminating program\n", get_time(LO));
 51 
 52 }

 0 Inside t1
 0 Inside t2
 0 Inside t2_t1
 4 from t2_t1_t1
 5 from t2_t1_t1
 8 from t2_t1_t1
 10 from t2_t1_t1
 12 from t2_t1_t1
 15 from t2_t1_t1
 16 from t2_t1_t1
 20 from t2_t1_t1
 20 from t2_t1_t1
 24 from t2_t1_t1
 25 from t2_t1_t1
 28 from t2_t1_t1
 30 from t2_t1_t1
 32 from t2_t1_t1
 35 from t2_t1_t1
 36 from t2_t1_t1
 40 Returning from t2
 40 from t2_t1_t1
 40 from t2_t1_t1
 44 from t2_t1_t1
 45 from t2_t1_t1
 48 from t2_t1_t1
 50 from t2_t1_t1
 52 from t2_t1_t1
 55 from t2_t1_t1
 56 from t2_t1_t1
 60 from t2_t1_t1
 60 from t2_t1_t1
 64 from t2_t1_t1
 65 from t2_t1_t1
 68 from t2_t1_t1
 70 from t2_t1_t1
 72 from t2_t1_t1
 75 from t2_t1_t1
 76 from t2_t1_t1
 80 from t2_t1_t1
 80 from t2_t1_t1
 84 from t2_t1_t1
 85 from t2_t1_t1
 88 from t2_t1_t1
 90 from t2_t1_t1
 92 from t2_t1_t1
 95 from t2_t1_t1
 96 from t2_t1_t1
 100 terminating t1
 200 terminating program

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