On Tue, Oct 22, 2013 at 3:29 AM, David Bullock < david.bull...@machaira.com.au> wrote:
> Hi Bob, > > > I tried searching the javadocs of RemoteEndpoint.Async and associated > interfaces, but could not find anything describing the threadsafe nature > (existing or not). It appears that the spec lets the implementation > determine how to handle stuff under the covers. This is fine, but we just > need to understand what that means to multi-threaded code that wants to > send messages. > JSR 356 Specification Section 5.1 Threading Consideration discusses the topic. In particular; [WSC-5.1-2] - "the implementation must not invoke an endpoint instance with more than one thread per peer at a time." [WSC-5.1-4] - "a websocket endpoint instance is never called by more than one container thread at a time per peer." cheers > > I'd have thought that where an interface doesn't declare that it is > threadsafe, one cannot assume that it will be. Further, if a > RemoteEndpoint represents 'the peer of a web socket conversation', > then a RemoteEndpoint, like a conversation, can surely support only a > single 'conversation state'? > > IMHO, the correct choice is for each thread to have its own > RemoteEndpoint. If the protocol being used happens to multiplex > multiple conversations to/from different endpoints over the same > TCP/UDP socket (for example), then the plumbing will do the > appropriate synchronization at that point - there would be no > advantage (and possibly some big disadvantages) for you to do your own > synchronization. Critically, a RemoteEndpoint does not necessarily > represent a 'heavyweight' object like a Socket, and you should not be > at pains to manage your own pool of them, nor necessarily (unless it > made sense for application logic) to have a queue of messages which is > dispatched from a single thread. > > However, I do think that many JSR's which ought to know better are > very lame about thread-safety guarantees for application authors, and > that more needs to be said in API documentation about patterns for > concurrent usage. I encourage you to lobby your particular JSR of use > to include this information in future releases of the specification. > I did my bit recently at https://java.net/jira/browse/SERVLET_SPEC-81 > > cheers, > David Bullock > > --------------------------------------------------------------------- > To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org > For additional commands, e-mail: users-h...@tomcat.apache.org > >
