ThreadSafeAppender.java

public class ThreadSafeAppender extends AppenderBase<ILoggingEvent> {
	static ThreadLocal<List<ILoggingEvent>> threadLocal = new ThreadLocal<>();

	@Override
	public void append(ILoggingEvent e) {
		List<ILoggingEvent> events = threadLocal.get();
		if (events == null) {
			events = new ArrayList<>();
			threadLocal.set(events);
		}
		events.add(e);
	}

	public static List<ILoggingEvent> getEvents() {
		return threadLocal.get();
	}

	public static void clearEvents() {
		threadLocal.remove();
	}
}