The Throwable is initially captured in the Message (usually
ParameterizedMessage or its garbage-free equivalent), but is later transferred
to the LogEvent.
By the time the LogEvent reaches the Layout, the Message instance may be a
different Object than the one that originally held the Throwable.
The Layout should get the Throwable from the LogEvent, not from the Message.
Remko
Sent from my iPhone
> On 5 Nov 2016, at 7:50,Nicholas Duane <nic...@msn.com> wrote:
>
> Thanks for the replies. Let me ask a more pointed question now as rummaging
> through the source will probably take me hours. I'm curious about the
> overloads with the throwable, for instance:
>
>
> logger.error("some message", <some throwable>);
>
>
> What's the expected behavior? Meaning, what is the logging framework going
> to do with the message and the exception? I know the message is usually
> output via the message property in the pattern layout. But what happens with
> the throwable? Is there some code responsible for constructing a message
> which combines the supplied message with the throwable exception message and
> callstack?
>
>
> I wrote the following simple java sample:
>
>
> import org.apache.logging.log4j.Logger;
> import org.apache.logging.log4j.LogManager;
>
> public class Test
> {
> private static final Logger logger = LogManager.getLogger(Test.class);
>
> public static void main(String[] args)
> {
> logger.info("entered main");
> try
> {
> throw(new IllegalArgumentException("bad argument"));
> }
> catch(Throwable t)
> {
> logger.error("caught exception", t);
> }
> logger.info("exiting main");
> }
> }
>
>
> Here is the log4j2.xml file:
>
>
> <?xml version="1.0" encoding="UTF-8"?>
> <Configuration status="WARN">
> <Appenders>
> <Console name="Console" >
> <PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level %logger{36}
> \
> - %msg%n"/>
> </Console>
> </Appenders>
> <Loggers>
> <Root level="info">
> <AppenderRef ref="Console"/>
> </Root>
> </Loggers>
> </Configuration>
>
>
> Here is the output to the console when I run the sample:
>
>
> [nick@thinkpad log4j]$ java Test
> 16:37:57.681 [main] INFO Test - entered main
> 16:37:57.683 [main] ERROR Test - caught exception
> java.lang.IllegalArgumentException: bad argument
> at Test.main(Test.java:13) [log4j/:?]
> 16:37:57.689 [main] INFO Test - exiting main
>
>
> So there does seem to be some code which is combining the message with the
> exception. Just wondering where that happens. Now onto my specific problem.
> We've got someone saying that when they use the error() method which takes a
> string message and an throwable the exception information is not making it to
> our central repository. We have written our own appender and our own layout.
> Here is a snippet from our appender:
>
>
> String serializedEvent = (String) getLayout().toSerializable(logEvent);
>
> Here is a snippet from our layout:
>
>
> String message = logEvent.getMessage().getFormattedMessage();
>
>
> It seems the message above does not include any exception info. What are we
> doing wrong?
>
>
> Thanks,
>
> Nick
>
> ________________________________
> From: Remko Popma <remko.po...@gmail.com>
> Sent: Friday, November 4, 2016 10:42 AM
> To: Log4J Users List
> Subject: Re: looking for source
>
> Sure. Start in AbstractLogger in the API module:
> https://github.com/apache/logging-log4j2/blob/master/log4j-api/src/main/java/org/apache/logging/log4j/spi/AbstractLogger.java
>
> and at some point you probably also want to look at the concrete subclass
> Logger in the core module:
> https://github.com/apache/logging-log4j2/blob/master/log4j-core/src/main/java/org/apache/logging/log4j/core/Logger.java
>
> Hope this helps to get you started.
>
> It may be easier to use an IDE and check out the whole project
> (https://logging.apache.org/log4j/2.x/source-repository.html).
> Log4j - Source Repository - Apache Log4j
> 2<https://logging.apache.org/log4j/2.x/source-repository.html>
> logging.apache.org
> Access from Behind a Firewall. Refer to the documentation of the SCM used for
> more information about access behind a firewall.
>
>
>
> Enjoy!
> Remko
>
> Sent from my iPhone
>
>> On 4 Nov 2016, at 23:29, Nicholas Duane <nic...@msn.com> wrote:
>>
>> I'm not that familiar with java and java conventions, package names, etc.
>> I'm trying to find the source for log4j2's implementation of
>> logger.error(String, Throwable);. Can someone point me to that? I was
>> looking around here:
>>
>>
>> https://git-wip-us.apache.org/repos/asf?p=logging-log4j2.git;a=tree;hb=refs/heads/master
>>
>>
>> But couldn't seem to find what I was looking for.
>>
>>
>> Thanks,
>>
>> Nick
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