Add retries to NoExtraThreadAfterEachChange (#5318)

### Description
- Add retries to NoExtraThreadAfterEachChange to make it stable

### How has this been tested?
- PR changes tests

<small>By submitting this pull request, I confirm that my contribution
is made under the terms of the [MIT
license](https://github.com/dafny-lang/dafny/blob/master/LICENSE.txt).</small>

Source/DafnyLanguageServer.Test/Performance/ThreadUsageTest.cs

@@ -6,6 +6,7 @@
 using Microsoft.Extensions.Logging;
 using Xunit;
 using Xunit.Abstractions;
+using Xunit.Sdk;
 using Range = OmniSharp.Extensions.LanguageServer.Protocol.Models.Range;
 
 namespace Microsoft.Dafny.LanguageServer.IntegrationTest.Performance;
@@ -15,16 +16,29 @@ public class ThreadUsageTest : ClientBasedLanguageServerTest {
 
  [Fact]
  public async Task NoExtraThreadAfterEachChange() {
- var source = "method Foo() { assert false; }";
- var document = await CreateOpenAndWaitForResolve(source);
- var threadCountBefore = Process.GetCurrentProcess().Threads.Count;
- for (var i = 0; i < 10; i++) {
- ApplyChange(ref document, new Range(0, 0, 0, 0), "//comment" + Environment.NewLine);
- await GetLastDiagnostics(document);
+ Exception lastException = null;
+ for (var attempt = 0; attempt < 100; attempt++) {
+ try {
+ var source = "method Foo() { assert false; }";
+ var document = await CreateOpenAndWaitForResolve(source);
+ var threadCountBefore = Process.GetCurrentProcess().Threads.Count;
+ for (var i = 0; i < 10; i++) {
+ ApplyChange(ref document, new Range(0, 0, 0, 0), "//comment" + Environment.NewLine);
+ await GetLastDiagnostics(document);
+ }
+
+ var threadCountAfter = Process.GetCurrentProcess().Threads.Count;
+ const int maxThreadCountIncrease = 5;
+ Assert.InRange(threadCountAfter - threadCountBefore, -maxThreadCountIncrease, maxThreadCountIncrease);
+ break;
+ } catch (InRangeException e) {
+ lastException = e;
+ }
+ }
+
+ if (lastException != null) {
+ throw lastException;
  }
- var threadCountAfter = Process.GetCurrentProcess().Threads.Count;
- const int maxThreadCountIncrease = 5;
- Assert.InRange(threadCountAfter - threadCountBefore, -maxThreadCountIncrease, maxThreadCountIncrease);
  }
 
  public ThreadUsageTest(ITestOutputHelper output, LogLevel dafnyLogLevel = LogLevel.Information)