[Mono-dev] ConcurrentStack with value type in 2.10

[Yuriy Solodkyy]

Hi,

It looks like the ConcurrentStack does not work with big enough
structures anymore.  12 bytes struct is enough to reproduce the
problem occasionally, 16 bytes structure to reproduce it immediately.
It worked fine in mono 2.8.  The following code shows that we may pop
inconsistent structure from the stack from time to time.

using System;
using System.Collections.Concurrent;
namespace CocurrentTest {
        class MainClass {
                struct Data {
                        public int A; public int B; public int C; public int D;
                        public Data(int v) {
                                A = v; B = -v; C = v; D = -v;
                        }
                }

                public static void Main (string[] args) {
                        Console.WriteLine ("Hello World!");
                        var data = new byte[1024 * 1024];
                        var stack = new ConcurrentStack<Data> ();

                        for (var i = 0; i < 50; i++) {

                                var thread = new System.Threading.Thread (v => {

                                        var rnd = new Random ();
                                        while (true) {
                                                int pushCount = rnd.Next (50);
                                                int popCount = rnd.Next (50);

                                                for (var k = 0; k <
pushCount; k++) {


                                                        var sample =
new Data (rnd.Next(Int32.MaxValue));
                                                        CheckSample (sample);

                                                        stack.Push (sample);
                                                }

                                                for (var k = 0; k <
popCount; k++) {
                                                        Data
retrievedSample = new Data();
                                                        if
(stack.TryPop (out retrievedSample)) {

CheckSample (retrievedSample);
                                                        }
                                                }
                                        }
                                }
                                );

                                thread.Start ();
                        }
                }

                static void CheckSample (Data sample){
                        if (sample.A != -sample.B || sample.A !=
sample.C || sample.B != sample.D)
                                throw new Exception (string.Format
("Invalid sample detected"));
                }
        }
}


-- 
Yuriy Solodkyy