lock count is not working properly while analysing dump file which is generated by dotnet-dump. i.e. lock count column when executing clrthreads

[CodingwithKetan]

Description

I tying to run clrthreads for below console application which is simulate deadlock so for thread1 and thread2 there should lock count as 1 for each

class Program
{
    static object lock1 = new object();
    static object lock2 = new object();

    static void Main(string[] args)
    {
        Console.WriteLine("Starting application...");

        Thread thread1 = new Thread(Thread1Work);
        Thread thread2 = new Thread(Thread2Work);
        
        thread1.Name = "thread1";
        thread2.Name = "thread2";

        thread1.Start();
        thread2.Start();

        thread1.Join();
        thread2.Join();

        Console.WriteLine("Exiting application...");
    }

    static void Thread1Work()
    {
        lock (lock1)
        {
            Console.WriteLine("Thread 1 acquired lock1");
            Thread.Sleep(1000); // Simulate work
            lock (lock2)
            {
                Console.WriteLine("Thread 1 acquired lock2");
            }
        }
    }

    static void Thread2Work()
    {
        lock (lock2)
        {
            Console.WriteLine("Thread 2 acquired lock2");
            Thread.Sleep(1000); // Simulate work
            lock (lock1)
            {
                Console.WriteLine("Thread 2 acquired lock1");
            }
        }
    }
}`

Configuration

I am using linux system

output

> clrthreads                                                                   
ThreadCount:      7
UnstartedThread:  0
BackgroundThread: 4
PendingThread:    0
DeadThread:       0
Hosted Runtime:   no
                                                                                                            Lock  
 DBG   ID     OSID ThreadOBJ           State GC Mode     GC Alloc Context                  Domain           Count Apt Exception
   0    1     c942 0000563E28BA0A60  2020020 Preemptive  00007F89728CAF58:00007F89728CB288 0000563E28B87D80 -00001 Ukn 
   6    2     c956 0000563E28BA7F50    21220 Preemptive  0000000000000000:0000000000000000 0000563E28B87D80 -00001 Ukn 
   7    4     c958 0000563E28BAC850    21220 Preemptive  0000000000000000:0000000000000000 0000563E28B87D80 -00001 Ukn (Finalizer) 
   2    5     c945 00007FC978001E90    20220 Preemptive  00007F89728CE038:00007F89728CF2C8 0000563E28B87D80 -00001 Ukn 
   9    6     c991 0000563E28C81A40  2021020 Preemptive  0000000000000000:0000000000000000 0000563E28B87D80 -00001 Ukn 
  10    7     c992 0000563E28C82C60  2021020 Preemptive  00007F89728CB2D0:00007F89728CD2A8 0000563E28B87D80 -00001 Ukn 
  11    8     c993 00007FC9780B4250  2021220 Preemptive  00007F897291FB40:00007F8972920FD0 0000563E28B87D80 -00001 Ukn 

and now if I am running syncblk there is showing that there are two syncblock and owning thread are thread1 and thread2 respectively

syncblk                                                                                                                                                                                                 
Index         SyncBlock MonitorHeld Recursion Owning Thread Info          SyncBlock Owner
    1 00007F88C8002C88            3         1 0000563E28C82C60 c992  10   00007f89728cb2b8 System.Object
    2 00007F88C8002CE0            3         1 0000563E28C81A40 c991   9   00007f89728cb2a0 System.Object
-----------------------------
Total           2
Free            0

The outputs of both are contradictory, Or let me correct if I am missing something

[tommcdon]

@kouvel @mikem8361

[CodingwithKetan]

I was using on version 9.0.553101+5b61d34de04d6100e6003415f7d7e9c4b971afd4

[mikem8361]

Sorry, I haven't responded sooner. As it turns out the lock count column in the clrthreads command is always -1 except for very old .NET Core versions or .NET Framework. The runtime removed that lock count support 5 years ago.

The syncblk command looks like it is correct. Is there any other issues or can we close this issue?

[CodingwithKetan]

Thank you @mikem8361!, then don't you think we should remove column it self because if someone is using/considering only "clrthreads" then it is giving false output.

[mikem8361]

The lock count == -1 basically means that it not available. We really don't want to change it or remove it. It has been this way for a long time.

Can we close this issue?

[CodingwithKetan]

@mikem8361, if you don't want to remove it I don't have issue with that but there is not any meaning of that. you can close the issue.