How to: Coordinate Multiple Threads of Execution

In order for your multithreaded components to be thread-safe, you must coordinate access to shared resources. If multiple threads attempt to access a shared resource at the same time, race conditions can result, causing corruption of data. You can avoid race conditions by using locks. For details on thread-safety and race conditions, see Thread-Safe Components.

To create a lock on an object

1. Identify the code that must be executed atomically and the object on which the code will be executed. For details, see Thread-Safe Components

2. Place a lock on that object and enclose your code inside that lock.

   This code will now be executed atomically on the locked object.

   SyncLock MyObject   ' This represents the start of the lock on MyObject.
   ' Insert code to be executed atomically on MyObject here.
   End SyncLock   ' This represents the end of the lock.
   

   lock (MyObject) 
      // All code inside the braces {} is executed with MyObject locked.
   {
      // Insert code to be executed atomically on MyObject here.
   }
   

See Also

Tasks

Walkthrough: Authoring a Simple Multithreaded Component with Visual Basic

Walkthrough: Authoring a Simple Multithreaded Component with Visual C#

Reference

BackgroundWorker

Concepts

Thread-Safe Components

Event-based Asynchronous Pattern Overview

Other Resources

Multithreading in Components