Tolga Kavukcu created LOG4J2-2060:
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Summary: 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: 2.8.2, 2.8.1
Reporter: Tolga Kavukcu
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.
So if a delay could happen 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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