Hello Husain,

I think the observed behavior lies in the implementation of
Parallel.ForEach. All your assumptions seem correct to me except that
Parallel.ForEach does not execute its actions on a separate thread or
separate task each.

If you look at mscorlib with ILSpy and find
System.Threading.Tasks.Parallel.ForEach you'll see that it does some heavy
optimization to find the right ratio of threads/tasks and load.

IMHO it may be reusing a task where your "x-correlation-id" was set (if
(i==3)) for other values of i, this is why you are seeing multiple modified
log outputs.

cheers,
alex

On Fri, Apr 7, 2017 at 10:04 AM, Dominik Psenner (JIRA) <j...@apache.org>
wrote:

>
>     [ https://issues.apache.org/jira/browse/LOG4NET-562?page=
> com.atlassian.jira.plugin.system.issuetabpanels:comment-
> tabpanel&focusedCommentId=15960445#comment-15960445 ]
>
> Dominik Psenner commented on LOG4NET-562:
> -----------------------------------------
>
> Have you tried to include the actual thread that the code executes in by
> logging System.Threading.Thread.CurrentThread.ManagedThreadId?
>
> > LogicalThreadContext is not per Thread
> > --------------------------------------
> >
> >                 Key: LOG4NET-562
> >                 URL: https://issues.apache.org/jira/browse/LOG4NET-562
> >             Project: Log4net
> >          Issue Type: Bug
> >          Components: Other
> >    Affects Versions: 2.0.8
> >         Environment: Windows 10, Visual Studio 17, .NET Framework 4.5.2
> >            Reporter: Husain Alshehhi
> >
> > LogicalThreadContext values are spread to many threads when they
> shouldn't.
> > This is an example:
> > {code:title=console.cs|borderStyle=solid}
> >             LogicalThreadContext.Properties["x-corralation-Id"] =
> "original-value";
> >             var list = new List<int> {1, 2, 3, 4, 5, 6, 7, 8, 9, 0};
> >             Parallel.ForEach(list, (i) =>
> >             {
> >                 if (i == 3)
> >                     LogicalThreadContext.Properties["x-corralation-Id"]
> = "modified-value";
> >                 logger.Info($"thread {i}.");
> >             });
> > {code}
> > this is the result
> > {code:title=badresult.txt|borderStyle=solid}
> > {"timestamp":"2017-04-05T12:31:41.117Z", "level":"INFO",
> "x-corralation-Id" : "original-value", "logger":"logger", "message":"thread
> 1.", "data":(null)}
> > {"timestamp":"2017-04-05T12:31:41.132Z", "level":"INFO",
> "x-corralation-Id" : "modified-value", "logger":"logger", "message":"thread
> 3.", "data":(null)}
> > {"timestamp":"2017-04-05T12:31:41.273Z", "level":"INFO",
> "x-corralation-Id" : "modified-value", "logger":"logger", "message":"thread
> 4.", "data":(null)}
> > {"timestamp":"2017-04-05T12:31:41.273Z", "level":"INFO",
> "x-corralation-Id" : "modified-value", "logger":"logger", "message":"thread
> 6.", "data":(null)}
> > {"timestamp":"2017-04-05T12:31:41.274Z", "level":"INFO",
> "x-corralation-Id" : "modified-value", "logger":"logger", "message":"thread
> 8.", "data":(null)}
> > {"timestamp":"2017-04-05T12:31:41.274Z", "level":"INFO",
> "x-corralation-Id" : "modified-value", "logger":"logger", "message":"thread
> 0.", "data":(null)}
> > {"timestamp":"2017-04-05T12:31:41.219Z", "level":"INFO",
> "x-corralation-Id" : "original-value", "logger":"logger", "message":"thread
> 7.", "data":(null)}
> > {"timestamp":"2017-04-05T12:31:41.179Z", "level":"INFO",
> "x-corralation-Id" : "original-value", "logger":"logger", "message":"thread
> 5.", "data":(null)}
> > {"timestamp":"2017-04-05T12:31:41.273Z", "level":"INFO",
> "x-corralation-Id" : "original-value", "logger":"logger", "message":"thread
> 2.", "data":(null)}
> > {"timestamp":"2017-04-05T12:31:41.234Z", "level":"INFO",
> "x-corralation-Id" : "original-value", "logger":"logger", "message":"thread
> 9.", "data":(null)}
> > {code}
> > This is what I was expecting:
> > {code:title=goodresult.txt|borderStyle=solid}
> > {"timestamp":"2017-04-05T12:31:41.117Z", "level":"INFO",
> "x-corralation-Id" : "original-value", "logger":"logger", "message":"thread
> 1.", "data":(null)}
> > {"timestamp":"2017-04-05T12:31:41.132Z", "level":"INFO",
> "x-corralation-Id" : "modified-value", "logger":"logger", "message":"thread
> 3.", "data":(null)}
> > {"timestamp":"2017-04-05T12:31:41.273Z", "level":"INFO",
> "x-corralation-Id" : "original-value", "logger":"logger", "message":"thread
> 4.", "data":(null)}
> > {"timestamp":"2017-04-05T12:31:41.273Z", "level":"INFO",
> "x-corralation-Id" : "original-value", "logger":"logger", "message":"thread
> 6.", "data":(null)}
> > {"timestamp":"2017-04-05T12:31:41.274Z", "level":"INFO",
> "x-corralation-Id" : "original-value", "logger":"logger", "message":"thread
> 8.", "data":(null)}
> > {"timestamp":"2017-04-05T12:31:41.274Z", "level":"INFO",
> "x-corralation-Id" : "original-value", "logger":"logger", "message":"thread
> 0.", "data":(null)}
> > {"timestamp":"2017-04-05T12:31:41.219Z", "level":"INFO",
> "x-corralation-Id" : "original-value", "logger":"logger", "message":"thread
> 7.", "data":(null)}
> > {"timestamp":"2017-04-05T12:31:41.179Z", "level":"INFO",
> "x-corralation-Id" : "original-value", "logger":"logger", "message":"thread
> 5.", "data":(null)}
> > {"timestamp":"2017-04-05T12:31:41.273Z", "level":"INFO",
> "x-corralation-Id" : "original-value", "logger":"logger", "message":"thread
> 2.", "data":(null)}
> > {"timestamp":"2017-04-05T12:31:41.234Z", "level":"INFO",
> "x-corralation-Id" : "original-value", "logger":"logger", "message":"thread
> 9.", "data":(null)}
> > {code}
>
>
>
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