Intrinsic locks - static synchronized method

Question

I am trying to understand the "static synchronized threads" - by theory when such a thread is invoked, it has to obtain a intrinsic lock on all the static variables. I wrote a sample program, but it is not giving me the desired results.
I have 3 threads, t1, t2, t3. t1 calls a static synchronized method crazy(), where i am using static int i. t2 and t3 calls a void function f2() and f3() which just prints i. Now i put a sleep in synchronized method crazy. I am expecting t1 to start and print i and go to sleep for 10 secs, release i and then t2 and t3 starts since crazy() holds an intrinsic lock on i. But the program calls t2 and t3 even if crazy puts the thread to sleep. What happend to the intrinsic lock on i ??
class RunnableThread implements Runnable{
static String i;
void f2() {
RunnableThread.i = "Two";
System.out.println(RunnableThread.i);
void f3() {
this.i = "three";
System.out.println(this.i);
static synchronized void crazy() {
try {
i = "One";
System.out.println(i);
Thread.sleep(10000);
System.out.println("Sleep done");
catch (Exception e ) {
e.printStackTrace();
public void run() {
System.out.println("Thread Name: " + Thread.currentThread().getName());
if (Thread.currentThread().getName().equals("two"))
f2();
} else if (Thread.currentThread().getName().equals("three"))
f3();
else if (Thread.currentThread().getName().equals("one"))
RunnableThread.crazy();
public static void main(String args[]) {
System.out.println("SOP from main");
RunnableThread rt1 = new RunnableThread();
RunnableThread rt2 = new RunnableThread();
RunnableThread rt3 = new RunnableThread();
Thread t1 = new Thread(rt1, "one");
t1.start();
Thread t2 = new Thread(rt2, "two");
t2.start();
Thread t3 = new Thread(rt3, "three");
t3.start();

Answer 1

lavanya.km wrote:
I am trying to understand the "static synchronized threads"Never heard of it. You might want to clarify your terminology.
- by theory when such a thread is invoked, it has to obtain a intrinsic lock on all the static variables. Nope. Doesn't happen.
I wrote a sample program,Ah, I see. You're creating synchronized static methods. Those do not even come close to "obtaining an intrinsic lock on all the static variables," even if there were such a thing as an "intrinsic lock," which there isn't. A synchronized method is just shorthand for enclosing the entire body in a sync block. In the case of a non-static method, it syncs on the "this" object. In the case of a static method, it syncs on the Class object for the class where the method is declared.
In no case does anything sync on "all the variables," static or not.