Using log4j2 with slf4j: java.lang.StackOverflowError

Question

So I have tried following this (non-maven implementation) and requirements in their web site for adding slf4j to log4j. and tried using this code

public static void main(String[] args) {
        Logger logger = LoggerFactory.getLogger(Main.class);
        logger.info("test");
    }

and added the following to my library

• log4j-api-2.3.jar
• log4j-core-2.3.jar
• log4j-sl4j-impl-2.3.jar
• log4j-to-sl4j-2.3.jar
• slf4j-api-1.7.12.jar

when I try running it I get the following error

Exception in thread "main" java.lang.StackOverflowError
    at java.util.concurrent.ConcurrentHashMap.get(ConcurrentHashMap.java:936)
    at java.util.concurrent.ConcurrentHashMap.containsKey(ConcurrentHashMap.java:964)
    at org.apache.logging.slf4j.SLF4JLoggerContext.getLogger(SLF4JLoggerContext.java:40)
    at org.apache.logging.slf4j.Log4jLoggerFactory.newLogger(Log4jLoggerFactory.java:37)
    at org.apache.logging.slf4j.Log4jLoggerFactory.newLogger(Log4jLoggerFactory.java:29)
    at org.apache.logging.log4j.spi.AbstractLoggerAdapter.getLogger(AbstractLoggerAdapter.java:47)
    at org.apache.logging.slf4j.Log4jLoggerFactory.getLogger(Log4jLoggerFactory.java:29)
    at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:284)
    at org.apache.logging.slf4j.SLF4JLoggerContext.getLogger(SLF4JLoggerContext.java:41)
    at org.apache.logging.slf4j.Log4jLoggerFactory.newLogger(Log4jLoggerFactory.java:37)
    at org.apache.logging.slf4j.Log4jLoggerFactory.newLogger(Log4jLoggerFactory.java:29)
    at org.apache.logging.log4j.spi.AbstractLoggerAdapter.getLogger(AbstractLoggerAdapter.java:47)
    at org.apache.logging.slf4j.Log4jLoggerFactory.getLogger(Log4jLoggerFactory.java:29)
    at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:284)...

Any idea where I am going wrong?

Answer 1

You're creating a call-loop with log4j-slf4j-impl-2.3.jar and log4j-to-slf4j-2.3.jar.

log4j-slf4j-impl-2.3.jar is the implementation of the adapter that sends slf4j calls to log4j.

log4j-to-slf4j-2.3.jar is sending log4j calls right back to slf4j. Remove this one.