How do synchronized static methods work in Java and can I use it for loading Hibernate entities?

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To address the question more generally…

Keep in mind that using synchronized on methods is really just shorthand (assume class is SomeClass):

synchronized static void foo() {
    ...
}

is the same as

static void foo() {
    synchronized(SomeClass.class) {
        ...
    }
}

and 

synchronized void foo() {
    ...
}

is the same as

void foo() {
    synchronized(this) {
        ...
    }
}

You can use any object as the lock. If you want to lock subsets of static methods, you can

class SomeClass {
    private static final Object LOCK_1 = new Object() {};
    private static final Object LOCK_2 = new Object() {};
    static void foo() {
        synchronized(LOCK_1) {...}
    }
    static void fee() {
        synchronized(LOCK_1) {...}
    }
    static void fie() {
        synchronized(LOCK_2) {...}
    }
    static void fo() {
        synchronized(LOCK_2) {...}
    }
}

(for non-static methods, you would want to make the locks be non-static fields)

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