@Override
	public final void start() {
		this.lifecycleLock.lock();
		try {
			if (!this.running) {
				this.doStart();
				this.running = true;
				if (logger.isInfoEnabled()) {
					logger.info("started " + this);
				}
				else {
					if (logger.isDebugEnabled()) {
						logger.debug("already started " + this);
					}
				}
			}
		}
		finally {
			this.lifecycleLock.unlock();
		}
	}
Base implementation of Spring Integration {@code MessageHandler} handling {@code Message}.

@author Janne Valkealahti
extensions/spring-xd-extension-gpfdist/src/main/java/org/springframework/xd/greenplum/gpfdist/AbstractGPFDistMessageHandler.java