NPE with Perf4j and Log4j

Question

when using Perf4j with Log4j, I get the following exception:

log4j:ERROR Error occured while converting date. java.lang.NullPointerException at java.lang.System.arraycopy(Native Method) at java.lang.AbstractStringBuilder.getChars(AbstractStringBuilder.java:328) at java.lang.StringBuffer.getChars(StringBuffer.java:201) at org.apache.log4j.helpers.ISO8601DateFormat.format(ISO8601DateFormat.java:130) at java.text.DateFormat.format(DateFormat.java:316) at org.apache.log4j.helpers.PatternParser$DatePatternConverter.convert(PatternParser.java:444) at org.apache.log4j.helpers.PatternConverter.format(PatternConverter.java:65) at org.apache.log4j.PatternLayout.format(PatternLayout.java:502) at org.apache.log4j.WriterAppender.subAppend(WriterAppender.java:302) at org.apache.log4j.WriterAppender.append(WriterAppender.java:160) at org.apache.log4j.AppenderSkeleton.doAppend(AppenderSkeleton.java:251) at org.apache.log4j.helpers.AppenderAttachableImpl.appendLoopOnAppenders(AppenderAttachableImpl.java:66) at org.perf4j.log4j.AsyncCoalescingStatisticsAppender$1.handle(AsyncCoalescingStatisticsAppender.java:200) at org.perf4j.helpers.GenericAsyncCoalescingStatisticsAppender$Dispatcher.run(GenericAsyncCoalescingStatisticsAppender.java:316) at java.lang.Thread.run(Thread.java:662) 

My log4j.xml looks like this:

 <!-- Appenders --> <appender name="console" class="org.apache.log4j.ConsoleAppender"> <param name="Target" value="System.out" /> <layout class="org.apache.log4j.PatternLayout"> <param name="ConversionPattern" value="%d %-5p: %c - %m%n" /> </layout> </appender> <!-- Perf4j Appender --> <appender name="CoalescingStatistics" class="org.perf4j.log4j.AsyncCoalescingStatisticsAppender"> <param name="TimeSlice" value="10000"/> <appender-ref ref="fileAppender"/> </appender> <!-- This file appender is used to output aggregated performance statistics --> <appender name="fileAppender" class="org.apache.log4j.FileAppender"> <param name="File" value="perfStats.log"/> <layout class="org.apache.log4j.PatternLayout"> <param name="ConversionPattern" value="%m%n"/> </layout> </appender> <!-- Perf4j Loggers --> <logger name="org.perf4j.TimingLogger" additivity="false"> <level value="INFO"/> <appender-ref ref="CoalescingStatistics"/> </logger> 

What am I doing wrong?

Answer 1

Hope I can help someone who just came across the same exception. So here is my answer:

It seems that the described exception appears only in a few circumstances. Here is my setup:

• Web application development
• Tomcat 6.0.32
• Log4j 1.2.15
• Perf4j 0.9.16

Also, it seems that the exception only occurs after redeploying the web application. An exception does NOT occur if you just started tomcat.

What I did to get rid of the exception:

• The log4j template has been changed from value="%d %-5p: %c - %m%n" to value="%d{yyyy-MM-dd HH:mm:ss} %-5p: %c - %m%n"
• Updated Log4j to version 1.2.16