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)
         


        

Answer 1

You can implement a Monitor wrapper that saves stack traces & thread names on enter.

Old way:

private object myLock = new object();

...
lock(myLock)
{
    DoSomething();
}
...

With code below:

private SmartLock myLock = new SmartLock();

...
myLock.Lock( () =>
{
    DoSomething();
}
);
...

Source:

public class SmartLock
{
    private object LockObject = new object();
    private string HoldingTrace = "";

    private static int WARN_TIMEOUT_MS = 5000; //5 secs


    public void Lock(Action action)
    {
        try
        {
            Enter();
            action.Invoke();
        }
        catch (Exception ex)
        {
            Globals.Error("SmartLock Lock action", ex);
        }
        finally
        {
            Exit();
        }

    }

    private void Enter()
    {
        try
        {
            bool locked = false;
            int timeoutMS = 0;
            while (!locked)
            {
                //keep trying to get the lock, and warn if not accessible after timeout
                locked = Monitor.TryEnter(LockObject, WARN_TIMEOUT_MS);
                if (!locked)
                {
                    timeoutMS += WARN_TIMEOUT_MS;
                    Globals.Warn("Lock held: " + (timeoutMS / 1000) + " secs by " + HoldingTrace + " requested by " + GetStackTrace());
                }
            }

            //save a stack trace for the code that is holding the lock
            HoldingTrace = GetStackTrace();
        }
        catch (Exception ex)
        {
            Globals.Error("SmartLock Enter", ex);
        }
    }

    private string GetStackTrace()
    {
        StackTrace trace = new StackTrace();
        string threadID = Thread.CurrentThread.Name ?? "";
        return "[" + threadID + "]" + trace.ToString().Replace('\n', '|').Replace("\r", "");
    }

    private void Exit()
    {
        try
        {
            Monitor.Exit(LockObject);
            HoldingTrace = "";
        }
        catch (Exception ex)
        {
            Globals.Error("SmartLock Exit", ex);
        }
    }
}