[jira] [Updated] (LOG4NET-605) AdoNetAppenderIssue Multithreaded Application Freeze

["Ralph Goers (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/LOG4NET-605?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Ralph Goers updated LOG4NET-605:
--------------------------------

LOG4NET is now dormant.  

> AdoNetAppenderIssue Multithreaded Application Freeze
> ----------------------------------------------------
>
>                 Key: LOG4NET-605
>                 URL: https://issues.apache.org/jira/browse/LOG4NET-605
>             Project: Log4net
>          Issue Type: Bug
>          Components: Core
>    Affects Versions: 2.0.8
>         Environment: Windows, MS SQL Server 2016
>            Reporter: Sebastian Morgenbesser
>            Priority: Major
>         Attachments: log4etbugshowcase_visual_studio_project.zip
>
>
> I recently noticed a strange issue with log4net and the AdoNetAppender and it would be nice if anyone could comment on this.
> Its quite an Edge Case I know but the implication is that the Application will freeze and no Exception is thrown which is kind of scary.
> I have made a small example C# project to illustrate the issue which I can provide, but first I want to explain the issue.
> The scenario is like this:
>  * Visual Studio C# Console Application. Log4net (latest version) embedded as dll, MS SQL Server 2016 (but I guess this doesn't matter), .NET Framework > 4.5
>  * The Application starts and the Logger is initialized (containing a AdoNetAppender pointing to an existing Database on MS SQL Server - localhost)
>  ** The code is something like this:
>  ** 
>  * After that happened, the Application is going to DROP the Database containing the Table that log4net will log to and recreates the database with all tables
>  ** This happens because every time the console starts the Log-Database should be empty  (I know there are other ways like truncate oder Drop Table but lets stay with me to understand the problem)
>  * So at this point the Database containing the Log Table has been recreated.
>  * Now the Application starts a number Threads (in my example 64, but I guess it works with less) and waits for them to finish
>  * In the Do() Method of the Thread, the thread simply tries to log an Error Message to the previously initialized logger
>  * The Result is that the Application freezes and will never return (0% CPU). Also no log messages arrive in the database.
>  * I am guessing there is some kind of deadlock situation inside log4net if multiple threads try to "initialize" the database connection to the recreated database again but in detail I have no idea what happens.
>  * No exception is thrown, the threads just never finish there Do() Method
>  So if I skip the part where I Recreate the database (with DROP und CREATE Database), then it works.
> Also if put a log statement after the recreation of the database but BEFORE the multithreaded part starts, it also works.



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