How to implement Async loggers in log4j2.properties file on WebSphere Server?

Below is my log4j property file and I want to make all loggers asynchronous. our projects runs on WebSphere server and we use buld.xml to build the application.

log4j.properties

log4j.rootLogger=warn, stdout, R

log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout

log4j.appender.stdout.layout.ConversionPattern=%d %5p [%t] (%F:%L) - %m%n

log4j.appender.R=org.apache.log4j.RollingFileAppender
log4j.appender.R.File=/export/opt/applications/gce/computegrid/logs/abcappxd.log

log4j.appender.R.MaxFileSize=10MB

log4j.appender.R.MaxBackupIndex=10

log4j.appender.R.layout=org.apache.log4j.PatternLayout
log4j.appender.R.layout.ConversionPattern=%d %p %t %c - %m%n

Below is the AppLogger class which we use to log the messages.

import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.Level;
import org.apache.logging.log4j.LogManager;
public class AppLogger implements IAppLogger {
    private static AppLogger instance = null;

    private transient Logger logger;
    private static final String LOGGER_NAME = " ";
    private static String SERVER_NAME = " ";
    
    private AppLogger() {      
        this.logger = LogManager.getLogger (LOGGER_NAME);
        try {
            AdminService adminService = AdminServiceFactory.getAdminService();
            SERVER_NAME = adminService.getProcessName();
        } catch (Exception e) { 
            SERVER_NAME="LOCAL";
        }
    }

    public static synchronized AppLogger getInstance() {
        if (instance == null) {
            instance = new AppLogger ();
        }
        return instance;
    }
    public void logDebug(final String strMsg, ContextInfoVO contextInfo, final String strClassName,final String strMethodName){
        logMessage(strMsg, contextInfo, strClassName, strMethodName, Level.DEBUG);
    }  
}

Below is the class where we use AppLogger Instance to print loggers

public class Dummy {

    private static AppLogger logger = AppLogger.getInstance();  
    void dummyMethod(){
        logger.logDebug(strMsg, contextInfo, strClassName, );
    }
}

Please help me on how I can Implement asynchronous logger in above code.