Chuck Felish created LOG4NET-454:
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Summary: Intermittent severe slowdown
Key: LOG4NET-454
URL: https://issues.apache.org/jira/browse/LOG4NET-454
Project: Log4net
Issue Type: Bug
Components: Appenders
Affects Versions: 1.2.13
Environment: ASP.NET MVC 5.2.2 Application, Windows 7 Professional
Reporter: Chuck Felish
Using RollingFileAppender with MinimalLock we found an extreme slowdown in the
processing of our application requests (from 300ms to up to 15s in some cases)
which was resolved when we deleted our log files. We also found that changing
the lock to Exclusive resolved the issue.
Interestingly file content seemed to be related, but not file size. When I took
the contents of a colleague's log file and pasted them into my own log file the
slowness issue appeared again. I then tried deleting about half the contents
and then causing the file to grow to larger than the original size but the
issue did not return. Pasting the original contents back into the file caused
the performance issue to return.
While Exclusive lock has resolved our issue for now, it's quite unexpected that
file contents would affect performance at all, and that the issue is does not
consistently reproduce even though configuration is unchanged.
I'm happy to demonstrate and/or share our problematic log files with you to
facilitate the resolution of this issue.
Our configuration is as follows:
<appender name="RollingFile" type="log4net.Appender.RollingFileAppender">
<file type="log4net.Util.PatternString"
value="Logs\%property{ExecutableName}_%env{COMPUTERNAME}.log" />
<lockingModel type="log4net.Appender.FileAppender+MinimalLock" />
<appendToFile value="true" />
<rollingStyle value="Size" />
<maximumFileSize value="5MB" />
<maxSizeRollBackups value="50" />
<preserveLogFileNameExtension value="true" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%d{yyyy-MM-dd HH:mm:ss.fff}
[%-5level][%5thread] %logger - %m%n" />
</layout>
</appender>
<root>
<!-- NOTE: This is overriden programatically by Log4NetConfig.cs -->
<level value="ALL" />
<!-- <appender-ref ref="ColorConsole" />-->
<appender-ref ref="RollingFile" />
</root>
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