ParallelLoopState.Break() and ParallelLoopState.Stop()

Question

User1904516115 posted

What is the difference between ParallelLoopState.Break() and  ParallelLoopState.Stop()? Please give an example

Answer 1

User-832373396 posted

Hi vinodkpasi,

Sir, here is the testing example

• ParallelLoopState.Break() 

     [TestMethod]
        public void TestMethod16() {
            var result = Parallel.For(1, 10, (i, state) => {
                if (i > 3)
                {
                    Debug.WriteLine("Break in iteration {0}", i);
                    state.Break();
                   
                }
                Debug.WriteLine("Completed iteration {0}", i);
            });
            Debug.WriteLine("done");
        }

Output

Completed iteration 1
Completed iteration 3
Break in iteration 5
Completed iteration 5
Completed iteration 2
Break in iteration 7
Completed iteration 7
Break in iteration 9
Break in iteration 4
Completed iteration 4
Completed iteration 9
done

• ParallelLoopState.Stop()

  [TestMethod]
        public void TestMethod17() {
            var result = Parallel.For(1,10, (i, state) => {           
                if (i > 3)
                {
                    Debug.WriteLine("Stop in iteration {0}", i);
                    state.Stop();
                    return;
                }
                Debug.WriteLine("Completed iteration {0}", i);
            });
            Debug.WriteLine("done" );
        }

Output

Completed iteration 1
Completed iteration 3
Stop in iteration 4
Stop in iteration 7
Stop in iteration 9
Stop in iteration 5
Completed iteration 2
done

It seems that it is a bit different between them.

Next

Test example

1 ParallelLoopState.Break()	2 ParallelLoopState.Stop()
[TestMethod] public void TestMethod16() { var c = 0; var result = Parallel.For(1, 100, (i, state) => { //if (state.ShouldExitCurrentIteration) //{ // if (state.LowestBreakIteration < i) // return; //} if (i>50) { Debug.WriteLine("Break in iteration {0}", i); state.Break(); } c++; Debug.WriteLine("Completed iteration {0}", i); }); Debug.WriteLine(c); Debug.WriteLine("done"); }	[TestMethod] public void TestMethod17() { var c = 0; var result = Parallel.For(1,100, (i, state) => { if (i > 50) { Debug.WriteLine("Stop in iteration {0}", i); state.Stop(); //return ; } //if (state.IsStopped) //{ // return; //} c++; Debug.WriteLine("Completed iteration {0}", i); }); Debug.WriteLine(c); Debug.WriteLine("done" ); } }
Completed iteration 1 Completed iteration 25 Completed iteration 26 Completed iteration 27 Completed iteration 28 Completed iteration 29 Completed iteration 30 Completed iteration 2 Completed iteration 49 Break in iteration 97 Break in iteration 73 Completed iteration 73 Completed iteration 97 Completed iteration 31 Completed iteration 50 Break in iteration 51 Completed iteration 51 Completed iteration 3 Completed iteration 4 Completed iteration 5 Completed iteration 6 Completed iteration 7 Completed iteration 8 Completed iteration 9 Completed iteration 10 Completed iteration 32 Completed iteration 33 Completed iteration 34 Completed iteration 35 Completed iteration 36 Completed iteration 37 Completed iteration 38 Completed iteration 11 Completed iteration 12 Completed iteration 13 Completed iteration 14 Completed iteration 15 Completed iteration 16 Completed iteration 39 Completed iteration 40 Completed iteration 41 Completed iteration 42 Completed iteration 17 Completed iteration 18 Completed iteration 43 Completed iteration 19 Completed iteration 44 Completed iteration 45 Completed iteration 46 Completed iteration 47 Completed iteration 48 Completed iteration 20 Completed iteration 21 Completed iteration 22 Completed iteration 23 Completed iteration 24 53 Done	Completed iteration 1 Completed iteration 25 Completed iteration 26 Completed iteration 27 Completed iteration 28 Completed iteration 29 Stop in iteration 73 Completed iteration 49 Completed iteration 2 Completed iteration 73 Stop in iteration 97 Completed iteration 97 Completed iteration 30 11 done
Completed iteration 1 Completed iteration 25 Completed iteration 26 Completed iteration 27 Completed iteration 28 Break in iteration 73 Completed iteration 73 Completed iteration 29 Completed iteration 49 Completed iteration 2 Completed iteration 3 Break in iteration 97 Completed iteration 97 Completed iteration 4 Completed iteration 5 Completed iteration 50 Break in iteration 51 Completed iteration 30 Completed iteration 31 Completed iteration 6 Completed iteration 7 Completed iteration 8 Completed iteration 9 Completed iteration 10 Completed iteration 11 Completed iteration 51 Completed iteration 32 Completed iteration 33 Completed iteration 34 Completed iteration 35 Completed iteration 36 Completed iteration 37 Completed iteration 12 Completed iteration 13 Completed iteration 14 Completed iteration 15 Completed iteration 16 Completed iteration 17 Completed iteration 18 Completed iteration 19 Completed iteration 38 Completed iteration 39 Completed iteration 40 Completed iteration 41 Completed iteration 42 Completed iteration 43 Completed iteration 44 Completed iteration 45 Completed iteration 20 Completed iteration 21 Completed iteration 22 Completed iteration 23 Completed iteration 24 Completed iteration 46 Completed iteration 47 Completed iteration 48 53 done	Completed iteration 1 Completed iteration 25 Completed iteration 26 Completed iteration 27 Completed iteration 28 Completed iteration 29 Stop in iteration 73 Completed iteration 73 Stop in iteration 97 Completed iteration 2 Completed iteration 49 Completed iteration 30 Completed iteration 97 11 done
Completed iteration 1 Completed iteration 25 Completed iteration 26 Completed iteration 27 Completed iteration 28 Break in iteration 73 Completed iteration 73 Completed iteration 29 Completed iteration 49 Completed iteration 2 Completed iteration 3 Break in iteration 97 Completed iteration 97 Completed iteration 4 Completed iteration 5 Completed iteration 50 Break in iteration 51 Completed iteration 30 Completed iteration 31 Completed iteration 6 Completed iteration 7 Completed iteration 8 Completed iteration 9 Completed iteration 10 Completed iteration 11 Completed iteration 51 Completed iteration 32 Completed iteration 33 Completed iteration 34 Completed iteration 35 Completed iteration 36 Completed iteration 37 Completed iteration 12 Completed iteration 13 Completed iteration 14 Completed iteration 15 Completed iteration 16 Completed iteration 17 Completed iteration 18 Completed iteration 19 Completed iteration 38 Completed iteration 39 Completed iteration 40 Completed iteration 41 Completed iteration 42 Completed iteration 43 Completed iteration 44 Completed iteration 45 Completed iteration 20 Completed iteration 21 Completed iteration 22 Completed iteration 23 Completed iteration 24 Completed iteration 46 Completed iteration 47 Completed iteration 48 53 done	Completed iteration 1 Completed iteration 25 Completed iteration 26 Completed iteration 27 Completed iteration 28 Stop in iteration 73 Completed iteration 73 Completed iteration 49 Stop in iteration 97 Completed iteration 2 Completed iteration 29 Completed iteration 97 10 done
Elapsed time	Elapsed time
about 303ms	about 94ms

We could see that if I remove the specified code for them, they are almost same. but from the test result, we could view the difference that if we use stop, it will stop reusing more resources quickly. and as the official document tells, if we want to look for something, the ParallelLoopState.Stop() is recommend.

and we could see that ParallelLoopState.<g class="gr_ gr_12894 gr-alert gr_gramm gr_inline_cards gr_run_anim Grammar only-ins doubleReplace replaceWithoutSep" id="12894" data-gr-id="12894">Stop</g> will stop until the iteration 97 <g class="gr_ gr_12895 gr-alert gr_gramm gr_inline_cards gr_run_anim Punctuation multiReplace" id="12895" data-gr-id="12895">completed;</g> but ParallelLoopState.Break() will continue which all maybe have opened <g class="gr_ gr_14158 gr-alert gr_gramm gr_inline_cards gr_run_anim Grammar only-ins doubleReplace replaceWithoutSep" id="14158" data-gr-id="14158">thread</g> <g class="gr_ gr_14101 gr-alert gr_gramm gr_inline_cards gr_run_anim Style replaceWithoutSep" id="14101" data-gr-id="14101">,then</g> stop.

Completed iteration 11 Completed iteration 51 Completed iteration 32 Completed iteration 33 Completed iteration 34 Completed iteration 35 Completed iteration 36 Completed iteration 37 Completed iteration 12 Completed iteration 13 Completed iteration 14 Completed iteration 15 Completed iteration 16 Completed iteration 17 Completed iteration 18 Completed iteration 19 Completed iteration 38 Completed iteration 39 Completed iteration 40 Completed iteration 41 Completed iteration 42 Completed iteration 43 Completed iteration 44 Completed iteration 45 Completed iteration 20 Completed iteration 21 Completed iteration 22 Completed iteration 23 Completed iteration 24 Completed iteration 46 Completed iteration 47 Completed iteration 48 53 done

Completed iteration 73 Completed iteration 49 Stop in iteration 97 Completed iteration 2 Completed iteration 29 Completed iteration 97 10 done

Guide

https://msdn.microsoft.com/en-us/library/system.threading.tasks.parallelloopstate.break(v=vs.110).aspx 

https://msdn.microsoft.com/en-us/library/system.threading.tasks.parallelloopstate.stop(v=vs.110).aspx 

With regards, Angelina Jolie

Answer 2

User1904516115 posted

Hi Angelina,

Thanks for reply. My doubt got cleared with your example.