Pascal schrieb: > > Per the java spec, "The load, store, read, and write actions on volatile > variables are atomic, even if the type of the variable is double or > long." Problem is, atomic in Java does not mean thread safe. I learned > this lesson the hard way back when I wrote my own thread factory. > Atomic in java means you will never get a mangled value. That is to say > that you won't see the value while it's in the process of being > changed. For example, if you have a non-volatile long you may get half > of it in one state and the other half in a different state. > > Bottom line, ++'ing a volatile is always atomic, just not thread safe. > I believe that is what you meant to ask yes?
Nope, reading and writing it is atomic, but ++'ing is reading *and* writing - as a context switch can happen in between, ++'ing is not atomic - and therefore not thread safe either. but the description above is right - as writes are atomic, you won't get mangled values. IMO volatile without synchronized is only a good idea for booleans (volatile booleans will be reread as often as possible, non-volatile booleans may be cached by each thread till the next enter/exit of a synchronized block) or for longs/doubles (for preventing mangled values), but not for ints. mihi _______________________________________________ devl mailing list devl at freenetproject.org http://hawk.freenetproject.org:8080/cgi-bin/mailman/listinfo/devl
