Need help - logs are getting mixed between 2 different applications running in same JVM

Question

Hi,

I am facing issues with logging of 2 applications deployed in same JVM.

I have 2 applications say A & B running in Websphere application server.

A is EJB project having log4j.jar in EJB jar

B is also EJB project but doesn't have log4j.jar as part of EJB jar and it refers to log4j jar available in Websphere lib.

A & B have independent Logger classes say ALogger.java and BLogger.java resp.

ALogger.java having static Logger logger = Logger.getLogger("A.class)");

BLogger.java having static Logger logger = Logger.getLogger("B.class)");

log4j.properties fot both are different and logs are written to diff file

App A:

log4j.rootLogger=ALL,ErrorAppender,file

log4j.appender.ErrorAppender.Threshold=WARN log4j.appender.ErrorAppender.layout.ConversionPattern=%-5p\t%d{ddMMyyyy-HH\:mm\:ss}\t%m%n log4j.appender.ErrorAppender.DatePattern='.'yyyy-MM-dd log4j.appender.ErrorAppender.layout=org.apache.log4j.PatternLayout log4j.appender.ErrorAppender.File=AErrorLog.log log4j.appender.ErrorAppender=org.apache.log4j.RollingFileAppender log4j.appender.ErrorAppender.MaxFileSize=1MB log4j.appender.ErrorAppender.MaxBackupIndex=5

log4j.appender.file.Threshold=DEBUG log4j.appender.file.layout.ConversionPattern=%-5p\t%d{ddMMyyyy-HH\:mm\:ss}\t%m%n log4j.appender.file.DatePattern='.'yyyy-MM-dd log4j.appender.file.layout=org.apache.log4j.PatternLayout log4j.appender.file.File=ALog.log log4j.appender.file=org.apache.log4j.RollingFileAppender log4j.appender.file.MaxFileSize=1MB log4j.appender.file.MaxBackupIndex=5

App B:

log4j.rootLogger=ALL,ErrorAppender,file

log4j.appender.ErrorAppender.Threshold=WARN log4j.appender.ErrorAppender.layout.ConversionPattern=%-5p\t%d{ddMMyyyy-HH\:mm\:ss}\t%m%n log4j.appender.ErrorAppender.DatePattern='.'yyyy-MM-dd log4j.appender.ErrorAppender.layout=org.apache.log4j.PatternLayout log4j.appender.ErrorAppender.File=BErrorLog.log log4j.appender.ErrorAppender=org.apache.log4j.RollingFileAppender log4j.appender.ErrorAppender.MaxFileSize=1MB log4j.appender.ErrorAppender.MaxBackupIndex=5

log4j.appender.file.Threshold=DEBUG log4j.appender.file.layout.ConversionPattern=%-5p\t%d{ddMMyyyy-HH\:mm\:ss}\t%m%n log4j.appender.file.DatePattern='.'yyyy-MM-dd log4j.appender.file.layout=org.apache.log4j.PatternLayout log4j.appender.file.File=BLog.log log4j.appender.file=org.apache.log4j.RollingFileAppender log4j.appender.file.MaxFileSize=1MB log4j.appender.file.MaxBackupIndex=5

log4j works fine when B is invoked after processing of A.

Problem : While A is running if B gets triggered,App A logs are getting written to App B's log file.How to fix this issue?

I have tried changing appender names for App B but it didn't work. This is urgent and any help regarding this problem is appreciated.

Answer 1

B is also EJB project but doesn't have log4j.jar as part of EJB jar and it refers to log4j jar available in Websphere lib

Try to change that. Have both projects bundle their own log4j. As of now, log4j is probably getting confused.

Answer 2

Log4J reads its configuration exactly once (unless instructed programmatically to do otherwise) within the scope of one classloader.

Your packaging strategy made WebSphere's Log4J load first, within WebSphere's classloader which is higher in the classloader hierarchy. Log4J initializes and loads; later, when your application (which has log4j embedded in it) makes a logging call, Log4J finds out that it is already initialized, so it doesn't even read the second property file.

The rule of thumb that must be followed to avoid similar cases is this: If you are using a utility JAR that reads configuration and stores it statically at the classloader level (for example: Log4J; Apache FOP; and many others), then you must bundle that JAR with your application and not have your code refer to AppServer-provided copies.

Follow that rule and you'll be golden... Even under WebSphere, which, for years, has been notoriously known as having some mess with its classloading strategies.