Locking thread conditionally and processing each time only one code - multithreading

Question

Firstly, new thread born independently of my code by external factory.
I have something integer key variable - "CODE". This variable "CODE" I received as result of a lot of calculating and request to DB (and maybe I need multi-threading protection of this "CODE").
I need lock thread only for the same "CODE", if currently "CODE" is handling now, thread with other "CODE" can not locking and handling without obstacle.
Thread with "CODE" now handling and locking need to immediately finish.
Also all this function must be working asynchronously with ASYNC/AWAIT.
I am using .NET Core 6.
It looks like a very common task, but what mechanism do I need to use?
Does code template for this task exist in inet?

Answer 1

This is my solution, but I'm not sure how it working with high uploading. I only try to test this code with high concurrency. If anybody has advice for me, please.
I realize solution with ConcurrentDictionary and locking critical section. To unlock main locker and using secondary locker I created new task.
This is schema of my solution.
Public Sub New(ByVal logger As ILogger(...)
....
WorkingServer = New ConcurrentDictionary(Of Integer, BashJob)()
WorkingVm = New ConcurrentDictionary(Of Integer, BashJob)()
End Sub
Private WorkingServer As ConcurrentDictionary(Of Integer, BashJob)
Private RequestNextJob As New Object
Public Async Function Execute(context As IJobExecutionContext) As Task Implements IJob.Execute
_logger.LogInformation($"Time {Now}")
Interlocked.Increment(Counter)
SyncLock RequestNextJob
' calculate CODE hidden in NextJob
...
Dim NextJob As BashJob = Res1.Result.Item1(0)
Dim Val1 As BashJob
Dim ServerWorking As Boolean = WorkingServer.TryGetValue(NextJob.toServer, Val1)
If Not ServerWorking Then
Dim AddSucess1 = WorkingServer.TryAdd(NextJob.toServer, NextJob)
If AddSucess1 Then
Dim ServerThread = New Thread(Sub() ServerJob(NextJob, New ServerClosure))
ServerThread.Start()
Else
Exit Function
End If
Else
Exit Function
End If
End SyncLock
End Function
Async Sub ServerJob(ByVal Prm As BashJob, ByVal Closure As ServerClosure)
Try
Closure.Res = Sql.ExecNonQuery(...)
...
'main processor
...
WorkingServer.TryRemove(Prm.toServer, Prm)
Catch ex As Exception
_logger.LogInformation($"ServerSsh ({Counter.ToString}) {Now.ToString} Server:{Prm.toServer} {Prm.i}:[{Prm.Command}] GettingError {ex.Message}")
Finally
WorkingServer.TryRemove(Prm.toServer, Prm)
End Try
End Sub
End Class
Public Class ServerClosure
Property Res As Integer
Property Server As ServerBashAsync
Property Connect As Tuple(Of Renci.SshNet.SshClient, Exception, Exception)
Property BashRet As Task(Of String)
Property IsCompleted As Integer
Property IsCompletedWithErr As Integer
End Class