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Posted to log4j-dev@logging.apache.org by "Gary Gregory (JIRA)" <ji...@apache.org> on 2016/01/05 08:33:40 UTC

[jira] [Resolved] (LOG4J2-1230) Don't concatenate SYSLOG Messages

     [ https://issues.apache.org/jira/browse/LOG4J2-1230?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Gary Gregory resolved LOG4J2-1230.
----------------------------------
       Resolution: Fixed
    Fix Version/s: 2.5.1

Fixed in Git master. Please verify and fix.

> Don't concatenate SYSLOG Messages
> ---------------------------------
>
>                 Key: LOG4J2-1230
>                 URL: https://issues.apache.org/jira/browse/LOG4J2-1230
>             Project: Log4j 2
>          Issue Type: Bug
>          Components: Core
>    Affects Versions: 2.5
>         Environment: Linux, Java7, WebLogic 12
>            Reporter: Vladimir Hudec
>            Assignee: Gary Gregory
>             Fix For: 2.5.1
>
>         Attachments: logging-log4j2.patch
>
>   Original Estimate: 8h
>  Remaining Estimate: 8h
>
> Under heavy traffic load several SYSLOG messages can be concatenated, which is not correct.
> The problem is, several threads in {{AbstractOutputStreamAppender}} can reach in the next code {{write()}} before one thread reaches {{flush()}} (the {{readLock.lock()}} is not lock at all)
> {code:java}
>     @Override
>     public void append(final LogEvent event) {
>         readLock.lock();
>         try {
>             final byte[] bytes = getLayout().toByteArray(event);
>             if (bytes.length > 0) {
>                 manager.write(bytes);
>                 if (this.immediateFlush || event.isEndOfBatch()) {
>                     manager.flush();
>                 }
>             }
>         } catch (final AppenderLoggingException ex) {
>             error("Unable to write to stream " + manager.getName() + " for appender " + getName());
>             throw ex;
>         } finally {
>             readLock.unlock();
>         }
>     }
> {code} 
> In DatagramOutputStream all messages are cumulated in instance variable {{private byte[] data;}}
> Synchronized methods don't help and in this case the synchronization in {{DatagramOutputStream}} is useless, as the correct synchronization should be provided in {{AbstractOutputStreamAppender}}.



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