Are all Thread methods (like getName/setName) thread-safe?

Question

Is it safe to use Thread's methods like setName / getName and some others from different threads? API does not say anything, but judging by the source code

private char name[];

public final void setName(String name) {
    checkAccess();
    this.name = name.toCharArray();
}

public final String getName() {
    return String.valueOf(name);
}

it seems that it may cause memory consistency errors.

Answer 1

Thread.getName() is a property than can be queried by anyone at any time. For example, a monitor utility constantly queries names of all threads. So the method has to be thread safe, otherwise, there's no clear protocol about who can safely access it and when.

Though it's always been puzzling why Thread uses a char[] to save its name, you are raising a more important question, getName() is obviously not correctly synchronized. If one thread does setName("abcd"), another thread may observe getName()->"ab\0\0".

I'll post the question to concurrency-interest list. see http://cs.oswego.edu/pipermail/concurrency-interest/2013-March/010935.html

Answer 2

"API does not say anything"

If an API does not say anything, than you never can asume that a method /class is thread safe. As you can see from the source code, the acess to name is not mutual exclusive.
But for me it seems, that name has either the old value or the new one, nothing in between, so it looks safe for must uses of get/setName().