Hello, I need to count number of error messages coming thru SLF4J into my app and integrate this number with System.exit() call at the end of the program. I have found that best solution would be to write an appender and dynamicaly add it in the code of my application. I am configuring logging by calling LoggerConfigurer (loading XML file) but I do not want to have my appender in this configuration - I do want to configure it dynamically not allowing user to modify XML and disable this error counter appender. But this does not work - the new appender method append() is never called. I think there is a problem with context or something. Here is the code: public class Test { final org.slf4j.Logger logger = org.slf4j.LoggerFactory.getLogger(Test.class); public void main(String[] args) { String fileName = "myfile.xml"; LoggerContext lc = (LoggerContext) LoggerFactory.getILoggerFactory(); try { JoranConfigurator configurator = new JoranConfigurator(); configurator.setContext(lc); // the context was probably already configured by default configuration // rules lc.shutdownAndReset(); configurator.doConfigure(fileName); ErrorCounterAppender errAppender = new ErrorCounterAppender(); Logger root = LoggerFactory.getLogger(LoggerContext.ROOT_NAME); errAppender.setContext(lc); errAppender.start(); ((ch.qos.logback.classic.Logger) root).addAppender(errAppender); logger.error("TEST"); logger.info("Number of errors: {}", errAppender.getErrorNumber()); // prints 0 System.exit(errAppender.getErrorNumber()); // returns 0 (instead of 1) } catch (Throwable t) { logger.warn("Cannot configure logger from location " + fileName, t); } StatusPrinter.print(lc); } } I think there must be some problem in the context or something. Or is there any better solution of my problem? Here is my appender: /** * Thread-safe implementation of error counter appender for LogBack. */ public class ErrorCounterAppender extends AppenderBase<LoggingEvent> { AtomicInteger errorCounter = new AtomicInteger(0); private Layout<LoggingEvent> layout; public ErrorCounterAppender() { } @Override public void setLayout(Layout<LoggingEvent> layout) { this.layout = layout; } public void resetErrorNumber() { errorCounter.set(0); } public int getErrorNumber() { return errorCounter.get(); } @Override public void start() { if (this.layout == null) { addError("No layout set for the appender named [" + name + "]."); return; } super.start(); } @Override public void append(LoggingEvent event) { if (event == null) return; if (Level.ERROR == event.getLevel()) { errorCounter.incrementAndGet(); } } } ----- -- Lukas Zapletal http://lukas.zapletalovi.com -- View this message in context: http://www.nabble.com/Error-counter-appender-tp22205463p22205463.html Sent from the Logback User mailing list archive at Nabble.com.