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From Dominik Psenner <dpsen...@gmail.com>
Subject Re: [jira] [Commented] (LOG4NET-562) LogicalThreadContext is not per Thread
Date Fri, 07 Apr 2017 08:56:24 GMT
Thanks Alexander, that's exactly what I was suspecting. 
Parallel.ForEach() may not necessarily be using different threads to 
execute the tasks. Also, the latest stuff that can be implemented with 
async/await levers high parallelism without the need of multithreading. 
Only I'm afraid you have to post this on JIRA as well because Husain is 
probably not subscribed to the mailing list.


On 2017-04-07 10:31, Alexander Houben wrote:
> 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) 
> <jira@apache.org <mailto:jira@apache.org>> wrote:
>
>
>         [
>     https://issues.apache.org/jira/browse/LOG4NET-562?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15960445#comment-15960445
>     <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
>     <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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>
>
>
> -- 
> Alexander Houben
> Head of Engineering
>
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