CSHARP.CONCURRENCY.STARVE.BLOCKING : Blocking in Critical Section (C#)

Summary

A blocking call occurs inside a synchronization block, hence increasing monitor contention and reducing performance.

Concurrency is an important but complex aspect of modern software. As a consequence, it is often used in an incorrect way, also because the subtleties of the C# memory model are not always understood. This checker identifies a large class of common programming errors due to incorrect uses of concurrency primitives, such as incorrect implementations of the singleton pattern and incorrect uses of the volatile field modifier, whose goal is to publish a field update to all executing cores. The latter, however, has a cost in terms of execution time.

Properties

WARNING_FILTER += discard class="Blocking in Critical Section (C#)"

Example

using System;
using System.Threading;

public class Sleepyhead  
{

  private static readonly object syncLock = new object();

  public Sleepyhead() { }


  public void ZzZ()
  {
  
    lock (syncLock) 
    {
      Thread.Sleep(500);                                    // "Blocking in Critical Section (C#)" warning issued here 
    }

  }
  
   public void PrintDream() 
   {
  
    lock (syncLock) 
    {
    
     for (int i = 0; i < 1000000; i++)
      Console.WriteLine("A Midsummer Night's Dream\n\\n"    // "Blocking in Critical Section (C#)" warning issued here 
            + "*Theseus*:\n"
            +"\t"+  "Now, fair Hippolyta, our nuptial hour\n"
            +"\t"+  "Draws on apace; four happy days bring in\n"
            +"\t"+  "Another moon: but, O, methinks, how slow\n"
            +"\t"+  "This old moon wanes! she lingers my desires,\n"
            +"\t"+  "Like to a step-dame or a dowager\n"
            +"\t"+  "Long withering out a young man revenue.\n"
            + "*Hippolyta*:\n"
                // ...
       );
    }

  }
  
  // ...

}

To solve this issues, the programmer should handle the heavy Thread.Sleep() and Console.WriteLine() methods asynchronously outside the synchronized body.

Resolution

Check if the warnings correspond to actual possible errors for a concurrent execution of the program.

Relevant Configuration File Parameters

The following configuration file parameters affect checks for this warning class.

• REPORT_SIMILAR_WARNINGS
• WARNING_FILTER