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From "Remko Popma (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (LOG4J2-2060) AbstactDatabase appender issue with AsyncLogger
Date Sun, 15 Oct 2017 13:37:00 GMT

    [ https://issues.apache.org/jira/browse/LOG4J2-2060?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16205113#comment-16205113
] 

Remko Popma commented on LOG4J2-2060:
-------------------------------------

I've committed a fix to master. It would be great if you could provide a unit test if you
have a chance.

> AbstactDatabase appender issue with AsyncLogger
> -----------------------------------------------
>
>                 Key: LOG4J2-2060
>                 URL: https://issues.apache.org/jira/browse/LOG4J2-2060
>             Project: Log4j 2
>          Issue Type: Bug
>          Components: Appenders
>    Affects Versions: 2.8.1, 2.8.2
>            Reporter: Tolga Kavukcu
>            Assignee: Remko Popma
>             Fix For: 2.10.0
>
>
> Log4j2 AsycLogger Implementation with a database appender has an issue.
> As i investigated the async logger mechanism works like that.
> Messages are put into DistruptorRingBuffer
> Than
> *RingBufferLogEventHandler*'s *onEvent* mehtod is called and message is passed to appender
asyncronously.
> In *AbstractDatabaseAppender* case
> The messages also put into an *ArrayList* to make batches for bulk insert to table.
> {code:java}
> @Override
> public final void append(final LogEvent event) {
>     this.readLock.lock();
>     try {
>         this.getManager().write(event);
>     } catch (final LoggingException e) {
>         LOGGER.error("Unable to write to database [{}] for appender [{}].", this.getManager().getName(),
>                 this.getName(), e);
>         throw e;
>     } catch (final Exception e) {
>         LOGGER.error("Unable to write to database [{}] for appender [{}].", this.getManager().getName(),
>                 this.getName(), e);
>         throw new AppenderLoggingException("Unable to write to database in appender:
" + e.getMessage(), e);
>     } finally {
>         this.readLock.unlock();
>     }
> }
> {code}
> Than *Abstract Database Manager* puts *LogEvent* into *ArrayList*
> {code:java}
> public final synchronized void write(final LogEvent event) {
>     if (this.bufferSize > 0) {
>         this.buffer.add(event);
>         if (this.buffer.size() >= this.bufferSize || event.isEndOfBatch()) {
>             this.flush();
>         }
>     } else {
>         this.connectAndStart();
>         try {
>             this.writeInternal(event);
>         } finally {
>             this.commitAndClose();
>         }
>     }
> }
> {code}
> After that correspoding *LogEvent* object can be re-used in the *DistruptorRingBuffer*
mechanism.
> When a delay happens in the database the *LogEvent* objects are overriden with same referance
which causes inconsitency while preparing batches.
> I believe this points to a bug or design problem. 
> I would like to contribute solution if anyone can guide where to start what might be
the possible design.



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