Production settings file for log4j?

Question

Here is my current log4j settings file. Are these settings ideal for production use or is there something I should remove/tweak or change? I ask because I was getting all my threads being hung due to log4j blocking. I checked my open file descriptors I was only using 113.

# ***** Set root logger level to WARN and its two appenders to stdout and R.
log4j.rootLogger=warn, stdout, R

# ***** stdout is set to be a ConsoleAppender.
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
# ***** stdout uses PatternLayout.
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
# ***** Pattern to output the caller's file name and line number.
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] (%F:%L) - %m%n

# ***** R is set to be a RollingFileAppender.
log4j.appender.R=org.apache.log4j.RollingFileAppender
log4j.appender.R.File=logs/myapp.log
# ***** Max file size is set to 100KB
log4j.appender.R.MaxFileSize=102400KB
# ***** Keep one backup file
log4j.appender.R.MaxBackupIndex=5
# ***** R uses PatternLayout.
log4j.appender.R.layout=org.apache.log4j.PatternLayout
log4j.appender.R.layout.ConversionPattern=%p %t %d %c - %m%n


#set httpclient debug levels
log4j.logger.org.apache.component=ERROR,stdout 
log4j.logger.httpclient.wire=ERROR,stdout 
log4j.logger.org.apache.commons.httpclient=ERROR,stdout 
log4j.logger.org.apache.http.client.protocol=ERROR,stdout

UPDATE*** Adding thread dump sample from all my threads (100)

"pool-1-thread-5" - Thread t@25
   java.lang.Thread.State: BLOCKED on org.apache.log4j.spi.RootLogger@1d45a585 owned by: pool-1-thread-35
    at org.apache.log4j.Category.callAppenders(Category.java:201)
    at org.apache.log4j.Category.forcedLog(Category.java:388)
    at org.apache.log4j.Category.error(Category.java:302)

Answer 1

This looks normal. I don't see how this alone could cause log4j blocking. Maybe you could post a thread dump of your issue?

Answer 2

%F:%L has serious performance impact. Although I don't see how they'd cause locking, I'd consider omitting them for production.

Answer 3

Are you creating a Logger for each class using the standard private static final Logger logger = Logger.getLogger(Foo.class); where Foo is the class in which the logger is declared? If you only have 1 Logger instance in your entire application, there could be some contention if there is a lot of logging.

Answer 4

This guy apparently had a similar problem (link).
It is puzzling though why your app is hanging. Are they all blocked at log4j classes? I see at least the one you posted was writing an "ERROR" log. Could that be the cause?

Maybe you want to post the full dump?