Improving detail printing in log4j

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I have the following code. The log level is INFO. How can we write the better code that the toString will not be executed ?

Set<Integer> resultUserIdsSet = new HashSet<>();
log.trace("userIdsSet={}", resultUserIdsSet.toString());

Note: The resultUserIdsSet contains milions of integers.

We use ch.qos.logback:logback-classic:jar:1.2.3

Everyone is telling you to use a Supplier, but there is no need for that. Just let the logger do the toString call:

log.trace("userIdsSet={}", resultUserIdsSet);

By removing .toString(), you are just passing a reference to the Set. If the trace level is not enabled, the logger call returns immediately; the cost is essentially negligible.

If and only if the trace level is enabled, then the logger will invoke toString() on the Set.

Ultimate log4j Tutorial for Java Logging – Best Practices, Resources , Improve your log4j logging skills with this tutorial - includes tips, best practices, Get the logger for the actual class name to be printed on */ private static final You can directly persist logs details into your database by simply  Configuring log4j involves assigning the Level, defining Appender, and specifying Layout objects in a configuration file. The log4j.properties file is a log4j configuration file which keeps properties in key-value pairs. By default, the LogManager looks for a file named log4j.properties in the CLASSPATH. The level of the root logger is defined

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Lazy loading by supplier:

Set<Integer> resultUserIdsSet = new HashSet<>();
log.trace(() -> "userIdsSet=" + resultUserIdsSet);

The Complete Log4j Manual, Some log4j components have been rewritten many times to improve performance​. Nevertheless 10 Given that on Windows NT printing on the console is rather  log4j is a very popular logging library for Java development.It provides convenient and flexible logging mechanism as well as fast performance. Putting log4j into your code is pretty easy as it requires minimum of work which mostly involves in configuring the logging system.

Log4j 2 Lock-free Asynchronous Loggers for Low-Latency Logging, Asynchronous logging can improve your application's performance by If not specified, the default exception handler will print a message and stack trace to the standard error output stream. See the details for system properties log4j2. Set the resource string variable to the value of the log4j.configuration system property. The preferred way to specify the default initialization file is through the log4j.configuration system property. In case the system property log4j.configuration is not defined, then set the string variable resource to its default value "log4j.properties".

Log4j – Log4j 2 Layouts, In Log4j 2 Layouts return a byte array. characters, specifying this charset will improve performance significantly. By default, the layout prints the logger name in full. See the ThreadContext class for more details. Log4j provides the ability to 'advertise' appender configuration details for all file-based appenders as well as socket-based appenders. For example, for file-based appenders, the file location and the pattern layout in the file are included in the advertisement.

Apache log4j 1.2, the problem in detail and has a or later to better defend against  Following is a sample configuration file log4j.properties to generate log files rolling over at midday and midnight of each day. # Define the root logger with appender file log4j.rootLogger = DEBUG, FILE # Define the file appender log4j.appender.FILE=org.apache.log4j.DailyRollingFileAppender # Set the name of the file log4j.appender.FILE.File=${log}/log.out # Set the immediate flush to true

Comments
  • We use ch.qos.logback:logback-classic:jar:1.2.3
  • I don't see that it supports lambdas in a general, so probably if(log.isTraceEnabled()) is the way to go.
  • In what log implementation and version the Supplier parameter exists ?
  • We use ch.qos.logback:logback-classic:jar:1.2.3. and the overloading with Supplier doesn't exists. In what log and version the Supplier exists ?