Double-Checked Locking

[QiAnXinCodeSafe]

ribbon/ribbon-httpclient/src/main/java/com/netflix/http4/NFHttpClientFactory.java

Lines 73 to 76 in e327877

	if (client == null){
	synchronized (lock) {
	client = namedClientMap.get(name);
	if (client == null){

double-Checked Locking is widely cited and used as an efficient method for implementing lazy initialization in a multithreaded environment.
Unfortunately, it will not work reliably in a platform independent way when implemented in Java, without additional synchronization.