[jira] [Commented] (LOG4PHP-196) Appender Rolling File: Seperate PHP processes attempting to roll the same log file will truncate the log.

["Charles Mack (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/LOG4PHP-196?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13474375#comment-13474375 ] 

Charles Mack commented on LOG4PHP-196:
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To put this in context, Kyle and I work on a system that has hundreds of PHP threads writing to a single UNC path log.   (Yes, we are looking into Mongo to store our logs).   As a result, when running LoggerAppenderRollingFile in prod, the files get truncated randomly on NTFS.   

There are some test scripts to replicate this issue that we can attach. While this is an extreme case, I'm sure there exists web hosting scenarios where this occurs. We have lost huge amounts of logs because the lack of Windows file locking and the LoggerAppenderRollingFile, hampering some major debugging issues.   

The proposed approach does not guarantee that the file will get rolled immediately after the first write to the file where the file is over the max file size.   

LoggerAppenderRollingFileWindows rolls files when:
- The file is over the max file size
- There is not an existing file-based mutex on that file
- The file we are trying to roll is writable (meaning nothing else is actively writing to it)

The next opportunity to roll the file, the file will be rolled.   This can result in some odd file sizes.  The main theme is balance when to roll a file versus protecting existing logs from being overwritten.

Once attached, to replicate, run the attached scripts with LoggerAppenderRollingFileWindows and LoggerAppenderRollingFile.
                
> Appender Rolling File: Seperate PHP processes attempting to roll the same log file will truncate the log.
> ---------------------------------------------------------------------------------------------------------
>
>                 Key: LOG4PHP-196
>                 URL: https://issues.apache.org/jira/browse/LOG4PHP-196
>             Project: Log4php
>          Issue Type: Bug
>          Components: Code
>    Affects Versions: 2.2.1
>         Environment: Windows
>            Reporter: Kyle Wiering
>              Labels: bug, fix, patch
>             Fix For: 2.3.0
>
>         Attachments: config_roll_windows.xml, LoggerAppenderRollingFileWindows.php, LoggerAppenderRollingFileWindowsTest.php, LoggerAutoloader.php
>
>   Original Estimate: 24h
>  Remaining Estimate: 24h
>
> Attaching a class extension to LoggerAppenderRollingFile named LoggerAppenderRollingFileWindows. This class enacts 'blocking' to keep seperate PHP processes from truncating the log file by attempting to roll the logs at/near the same exact time.  It also uses a 'rename' in a manner that is much quicker then a copy for large files.  

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