Hi, I assume you are worried that (1) can be moved by the compiler below "executor.execute()" or on processors with weak memory models changes from (1) might not be fully visible to other threads when (2) is executed. I believe it is not going to happen, as (1) should happen before "executor.execute()" (because they are on the same thread), which in turn should happen before retrieving a task for execution (because they are synchronised via task queue), which again happens before (2) (because on the same thread with the retrieving operation).
Best regards, Cezary On Tue, Sep 25, 2018 at 5:52 PM John Hening <[email protected]> wrote: > public class Test { > ArrayList<X> xs; > ArrayList<Doer> doers; > Executor executor = Executors.newSingleThreadExecutor(); > > static class Doer { > public void does(X x){ > x.f(); // > (2) > } > } > > void test() { > for(X x : xs){ > x.f(); // > (1) > > for(Doer d : doers) { > executor.execute(() -> d.does(x)); > } > } > } > } > > > > > For my eye, if X.f is not synchronized it is incorrect because of two > facts (and only that two facts): > > 1. Obviously, there is data race between (1) and (2). There are no more > data races here. (doers contains different objects) > 2. There is no guarantee that (1) will be executed before (2). Yes? > > If X.f would be synchronized that code will be correct because: > 1. There is no data race. > 2. There is guarantee that (1) will be executed before (2) because (1) is > a synchronization action and Executor.execute is also a synchronization > access (not specifically execute itself) > > Yes? > > -- > You received this message because you are subscribed to the Google Groups > "mechanical-sympathy" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > For more options, visit https://groups.google.com/d/optout. > -- Cezary Biernacki Director of Software Development crosswordcybersecurity.com @crosswordcyber Crossword Cybersecurity Plc is a public limited company registered in England and Wales. Registered number: 08927013. Registered office: 6th Floor, 60 Gracechurch Street, London, EC3V 0HR. -- You received this message because you are subscribed to the Google Groups "mechanical-sympathy" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
