CODEWITHSUNDEEP
javamultithreadinglogginglog4j
Asim
Asim

Reputation: 443

Printing thread id in log file using log4j

I am trying to print the id of the thread for which the logging is being done in my logfile. I did it at code level by log.info(Thread.currentThread().getId()) where "log" is Logger class object but this is not what i exactly want. Actually my application is a large distributed application and it is not possible to add Thread.currentThread().getId() with every log.info("something") in the code. Is there anyway by which i can just make any change in my log4j.xml file and print threads id for every log.info in my code. This is my log4j.xml

<log4j:configuration debug="true">
<!-- File Appenders -->

<appender name="EventsAndErrorsFileAppender" class="org.apache.log4j.RollingFileAppender">
    <param name="File" value="EventsAndErrors.xml" />
    <param name="Datepattern" value="'.'yyyy-MM-dd-HH" />
    <param name="MaxFileSize" value="1000KB" />
    <param name="MaxBackupIndex" value="140" />
    <layout class="org.apache.log4j.PatternLayout">
        <param name="ConversionPattern" value="%d{ISO8601} %-5p [%C] %m%n" />
    </layout>
    <filter class="org.apache.log4j.varia.LevelRangeFilter">
        <param name="LevelMin" value="INFO" />
        <param name="LevelMax" value="ERROR" />
    </filter>
</appender>

<root>
    <priority value="debug" />
    <appender-ref ref="EventsAndErrorsFileAppender" />
    <appender-ref ref="ExceptionFileAppender" />
</root>

Now i am assuming that I can add something in my Layout in xml to print the thread. I am also attaching the sample code in which i am trying this just for reference

import org.apache.log4j.Logger;

class MyThread extends Thread implements MyInterface
  {
   public void run()
    {
    int i = 0;
    while(i < 10)
    {
        System.out.println(Thread.currentThread().getId()+"In first        thread");
        log.info(Thread.currentThread().getId());
        log.error(Thread.currentThread().getId());
        System.out.println();
        i++;
    }   

  }
}
class MyThread1 extends Thread implements MyInterface
{

public void run()
{
    int i = 0;
    while(i < 10)
    {
        System.out.println(Thread.currentThread().getId()+"In secound thread");
        log.info(Thread.currentThread().getId());
        log.debug("debug");
        System.out.println();
        i++;
    }
}
}

public class MyClass implements MyInterface
{
 public static void main(String[] args) {
    // TODO Auto-generated method stub


    MyThread thread1 = new MyThread();
    MyThread1 thread2 = new MyThread1();


    log.info("logging stareted");
    thread1.start();
    thread2.start();
 } 
}

Any guidance would be aprreciated. Thanks

Upvotes: 24

Views: 49803

Answers (3)

Sprooose
Sprooose

Reputation: 514

If you are using Log4j 1.x then you could create another class that implements the functions of Log4j. Modify the debug method to append the Thread Id to the message.

However, you will need to bulk replace Log4j definitions with a reference to your own log class, across your codebase. I assume you have a line at the top of your class file with something like: 

Logger log = Logger.getLogger(MyService.class.getName());

And that would need to be replaced with a reference to your class instead.

As this class will be the only point that Log4j is now referenced in your Application, it makes it easy for you to replace the logging library if you ever wish to.

Upvotes: 2

Fildor
Fildor

Reputation: 16104

%t in the ConversionPattern gives you the thread's name.

Not the same as Thread ID but better than nothing and works without touching the code.

Update: As yuugen's answer points out: in log4j 2.x there is %tid for thread id. (+1 for his answer from me, adding it here for completeness. If this helps you please upvote his answer!)

Upvotes: 29

yuugen
yuugen

Reputation: 671

In log4j 2 https://logging.apache.org/log4j/2.x/manual/layouts.html#PatternLayout

%tid prints the thread ID

Upvotes: 57

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