I'm not sure why this thread was revived, but since there are several new answers, I will chime in too.
After nearly 100 nights in European hostels, my input is that yes, a regular Master combo lock will work everywhere I've been. But as noted, about any lock can be picked, so my normal procedure is to leave the locker unlocked. To do otherwise seems to me to advertise that you have something worth stealing. Probably I have used my combo lock twice in all this travel. I do sleep with certain things in my bed if I'm worried about them; I wear a money belt all the time unless showering. I do travel with a tablet, although not a newer sexy one. When I'm out, I just wrap it in clothes in my luggage and no one has ever bothered it. I have only one or two inexpensive and obviously costume pairs of earrings in my luggage. I travel with only the walking shoes on my feet and one pair of slightly worn ballet flats for rare fancy evening events; I keep those 'hidden" all the time. (Granted, my small foot size helps too.) If you leave any current, craveable, expensive sneakers in the room, I would consider locking those up.
But really, even though I believe accounts of things being stolen in hostels, I haven't known of it happening in my room, so it must be relatively rare. Just don't leave the bait in the open and easy to find, and that's probably as good as the best lock you can deploy. Also consider not taking your most theft-worthy stuff with you.