c# - Identify the thread which holds the lock

Question

one of the threads in my application blocked at the following lock statement and resulted in a deadlock

void ExecuteCommand()
{
    lock(this._lockinstance)
    {
        // do some operation
    }
}

---

Is it possible to easily identify which thread is currently holding the lock?.. My application has more than 50 threads, which makes it difficult to go through each callstack using visual studio to locate the thread that holds the lock

Answer 1

Some sample code to try out:

class Test {
    private object locker = new object();
    public void Run() {
        lock (locker) {  // <== breakpoint here
            Console.WriteLine(System.Threading.Thread.CurrentThread.ManagedThreadId);
        }
    }
}

Set a breakpoint on the indicated line. When it breaks, use Debug + Windows + Memory + Memory 1. Right click the window and choose "4-byte Integer". In the Address box, type &locker. The 2nd word is the thread ID of the thread that owns the lock. Step past the lock statement to see it change.

Beware that the number is the managed thread ID, not the operating system thread ID that you see in the Debug + Windows + Threads window. That kinda sucks, you probably should add some logging to your program that dumps the value of ManagedThreadId so you have a way to match the value to a thread. Update: fixed in later VS versions, the Debug > Windows > Threads debugger window now shows the ManagedThreadId.