fix infinite loop in foregroundgc test (#106006)

* fix infinite loop for foregroundgc

* Update src/tests/GC/Features/BackgroundGC/foregroundgc.cs

Co-authored-by: Mark Plesko <[email protected]>

* remove redundant volatile and clean the code

---------

Co-authored-by: Mukund Raghav Sharma (Moko) <[email protected]>
Co-authored-by: Mark Plesko <[email protected]>

src/tests/GC/Features/BackgroundGC/foregroundgc.cs

@@ -12,6 +12,7 @@ namespace ForegroundGC
     class ForegroundGC
     {
         static bool done = false;
+        readonly static object _lock = new object();
         static long maxAlloc = 1024 * 1024 * 1024;  //1GB max size
         static int size = 30;
         static int Main(string[] args)
@@ -70,7 +71,11 @@ static int Main(string[] args)
                 }
             }
 
-            done = true;
+            lock(_lock) 
+            {
+                done = true;
+            }
+
             t.Join();
             Console.WriteLine("List count=" + List1.Count);
 
@@ -82,8 +87,9 @@ static int Main(string[] args)
 
         static void AllocateTemp()
         {
-            while (!done)
+            while (true)
             {
+                lock(_lock) { if (done) { break; } }
                 byte[] b = new byte[30];
                 byte[] b2 = new byte[100];
             }