Question

Can I use string as locker in the Lock ?

lock("something")

Can I do lock without braces if its only one line ?

lock("something") foo();

Answer 1

1) Yes, strings are (generally) interned (by default, thanks @Eric), so any instance of the same "something" would point to the same object, therefore you’d be ok. This is very bad practice though, because someone else, in another library for example, could lock on your string, thus giving the potential for deadlocks. See here: Using string as a lock to do thread synchronization

You should do this:

private static readonly object mutex = new object();

lock(mutex)
{
    //....
}

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2) Yes, same with all statements. Anything* where you have:

{
    // One line
}

could just be

// One line

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*Almost anything, see @LukeH’s example of the catch block, which requires the braces.