SpringBoot Logging to Log4j2 MongoDb4 Appender ERROR on trace, debug and info level.

Logging to Log4j2 MongoDb4 Appender on trace, debug and info log level give the following error ERROR Recursive call to appender but give success result and the log got written to the mongodb database when using warn or error log level. Possibly something recursive call happens with info log level that causing this bug. See this article

Here is the repository that contain the very minimal code to reproduce the error. The configuration is provided in the log4j2-spring.xml file.

Comment From: wilkinsona

Thanks for the sample. This doesn't appear to be a Spring Boot problem. I renamed log4j2-spring.xml to log4j2.xml and modify Log4j2Mongodb4AppenderApplication to remove the use of Spring Boot:

package com.example.demo;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class Log4j2Mongodb4AppenderApplication {

    private static final Logger log = LoggerFactory.getLogger(Log4j2Mongodb4AppenderApplication.class);

    public static void main(String[] args) {
        log.trace("Trace level message");
        log.debug("Debug level message");
        log.info("Info level message");
        log.warn("Warn level message");
        log.error("Error level message");
    }

}

The same 2021-07-09 14:26:38,698 main ERROR Recursive call to appender MongoDbAppender problem occurred.

Here's the stack of the recursive call which may help you to diagnose the problem:

AppenderControl.isRecursiveCall() line: 105 
AppenderControl.shouldSkip(LogEvent) line: 88   
AppenderControl.callAppender(LogEvent) line: 81 
LoggerConfig.callAppenders(LogEvent) line: 540  
LoggerConfig.processLogEvent(LogEvent, LoggerConfig$LoggerConfigPredicate) line: 498    
LoggerConfig.log(LogEvent, LoggerConfig$LoggerConfigPredicate) line: 481    
LoggerConfig.log(String, String, StackTraceElement, Marker, Level, Message, Throwable) line: 456    
AwaitCompletionReliabilityStrategy.log(Supplier<LoggerConfig>, String, String, StackTraceElement, Marker, Level, Message, Throwable) line: 82   
Logger.log(Level, Marker, String, StackTraceElement, Message, Throwable) line: 161  
Logger(AbstractLogger).tryLogMessage(String, StackTraceElement, Level, Marker, Message, Throwable) line: 2205   
Logger(AbstractLogger).logMessageTrackRecursion(String, Level, Marker, Message, Throwable) line: 2159   
Logger(AbstractLogger).logMessageSafely(String, Level, Marker, Message, Throwable) line: 2142   
Logger(AbstractLogger).logMessage(String, Level, Marker, String) line: 2022 
Logger(AbstractLogger).logIfEnabled(String, Level, Marker, String) line: 1875   
Log4jLogger.info(String) line: 179  
SLF4JLogger.info(String) line: 71   
SingleServerCluster(BaseCluster).getDescription() line: 188 
SingleServerCluster.getDescription() line: 41   
MongoClientDelegate.getConnectedClusterDescription() line: 127  
MongoClientDelegate.createClientSession(ClientSessionOptions, ReadConcern, WriteConcern, ReadPreference) line: 87   
MongoClientDelegate$DelegateOperationExecutor.getClientSession(ClientSession) line: 258 
MongoClientDelegate$DelegateOperationExecutor.execute(WriteOperation<T>, ReadConcern, ClientSession) line: 182  
MongoCollectionImpl<TDocument>.executeSingleWriteRequest(ClientSession, WriteOperation<BulkWriteResult>, Type) line: 1009   
MongoCollectionImpl<TDocument>.executeInsertOne(ClientSession, TDocument, InsertOneOptions) line: 470   
MongoCollectionImpl<TDocument>.insertOne(TDocument, InsertOneOptions) line: 453 
MongoCollectionImpl<TDocument>.insertOne(TDocument) line: 447   
MongoDb4Connection.insertObject(NoSqlObject<Document>) line: 97 
NoSqlDatabaseManager<W>.writeInternal(LogEvent, Serializable) line: 83  
NoSqlDatabaseManager<W>(AbstractDatabaseManager).writeThrough(LogEvent, Serializable) line: 291 
NoSqlDatabaseManager<W>(AbstractDatabaseManager).write(LogEvent, Serializable) line: 264    
NoSqlAppender(AbstractDatabaseAppender<T>).append(LogEvent) line: 110   
AppenderControl.tryCallAppender(LogEvent) line: 156 
AppenderControl.callAppender0(LogEvent) line: 129   
AppenderControl.callAppenderPreventRecursion(LogEvent) line: 120    
AppenderControl.callAppender(LogEvent) line: 84 
LoggerConfig.callAppenders(LogEvent) line: 540  
LoggerConfig.processLogEvent(LogEvent, LoggerConfig$LoggerConfigPredicate) line: 498    
LoggerConfig.log(LogEvent, LoggerConfig$LoggerConfigPredicate) line: 481    
LoggerConfig.log(String, String, StackTraceElement, Marker, Level, Message, Throwable) line: 456    
AwaitCompletionReliabilityStrategy.log(Supplier<LoggerConfig>, String, String, StackTraceElement, Marker, Level, Message, Throwable) line: 82   
Logger.log(Level, Marker, String, StackTraceElement, Message, Throwable) line: 161  
Logger(AbstractLogger).tryLogMessage(String, StackTraceElement, Level, Marker, Message, Throwable) line: 2205   
Logger(AbstractLogger).logMessageTrackRecursion(String, Level, Marker, Message, Throwable) line: 2159   
Logger(AbstractLogger).logMessageSafely(String, Level, Marker, Message, Throwable) line: 2142   
Logger(AbstractLogger).logMessage(String, Level, Marker, String) line: 2022 
Logger(AbstractLogger).logIfEnabled(String, Level, Marker, String) line: 1875   
Log4jLogger.info(String) line: 179  
Log4j2Mongodb4AppenderApplication.main(String[]) line: 13   

I suspect it's because Mongo's client is performing some info-level logging while it's being used to log something.