But I read this in the libuv documentation: it is *imperative to make sure that no function which runs periodically in the loop thread blocks when performing I/O or is a serious CPU hog*, because this means the loop slows down and events are not being dealt with at full capacity
The only solution seems to launch another thread, as the event loop would be block when the task is running, Receiving new connections from other clients would be blocked until the task as finished. I learned about node cluster or using a supervisor as pm2 , but I would rather make it as efficient as possible first and then think about clustering. On Saturday, 16 November 2013 20:01:47 UTC, Ben Noordhuis wrote: > > On Sat, Nov 16, 2013 at 8:14 PM, João Henriques > <[email protected]<javascript:>> > wrote: > > > > I'm building a module to be used on a server application that does some > > heavy work on the background, and the best design I thought for > > not blocking node's main event loop was creating a new thread and a new > > event loop with libuv, keeping it referenced in the background until > someone > > needs it, > > > > > > /************************************************** > > * Module initialization > > **************************************************/ > > > > uv_loop_t *second_threaded_loop; > > > > void create_loop(void *) > > { > > uv_run(second_threaded_loop, UV_RUN_DEFAULT); > > } > > > > void init (Handle<Object> target) > > { > > NanScope(); > > > > uv_thread_t thread_loop; > > uv_async_t async; > > > > second_threaded_loop = uv_loop_new(); > > > > // Reference the second loop so it keeps on idle > > uv_async_init(second_threaded_loop, &async, NULL); > > > > uv_thread_create(&thread_loop, create_loop, NULL); > > > > // .... > > } > > > > /************************************************** > > * Then, a random function running on > > * the main loop does > > **************************************************/ > > > > NAN_METHOD(Foo::doHeavyOperation) > > { > > // ... > > > > uv_work_t* req = new uv_work_t; > > > > random_context_struct *ctx = new random_context_struct; > > // ctx->handle is a Handle<Object> > > ctx->handle = Persistent<Object>::New(args.This()); > > > > req->data = /* random context */; > > > > uv_queue_work(second_threaded_loop, req, startHeavyOpeation, > EmitMessage); > > > > // .... > > > > NanReturnUndefined(); > > } > > > > /************************************************** > > * After startHeavyOpeation ends, Emit Message is called > > * Where it supossly should emit an event > > * informing that the task finished > > **************************************************/ > > > > void EmitMessage(uv_work_t *req, int status) > > { > > random_context_struct *ctx = (random_context_struct*)req->data; > > > > Local<Value> argv[1] = { NanSymbol("parsed") }; > > > > TryCatch tc; > > > > MakeCallback(ctx->handle, "done", 1, argv); > > > > if (tc.HasCaught()) > > printf("Error occured"); > > } > > > > > > > > Now, if I run this task on the main event loop the operation succeeds > and > > the event is triggered, > > but in the second loop the application prematurely ends, without any > > explicit error being thrown, or being caught. > > > > A second loop to me seems the best idea, because blocking in the main > event > > loop is not be acceptable as the server > > will be receiving new connections from other users. Creating a thread > for > > each request would not be acceptable too, > > as the overhead would be unmanageable. A second event loop on a child > thread > > seems a reasonably approach but emitting seems not to be possible. > > V8 as it's used in node.js is not thread safe. You cannot call V8 > functions from another thread.* > > Do you need a separate event loop? The uv_queue_work() function runs > the work callback in a separate thread and invokes the done callback > on the original thread (i.e. the main thread.) > > * V8 can be entered from different threads only if you use appropriate > mutual exclusion with v8::Locker and v8::Unlocker objects. That won't > help in your case because your worker thread would block the main > thread if it somehow acquired the Locker. > -- -- Job Board: http://jobs.nodejs.org/ Posting guidelines: https://github.com/joyent/node/wiki/Mailing-List-Posting-Guidelines You received this message because you are subscribed to the Google Groups "nodejs" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/nodejs?hl=en?hl=en --- You received this message because you are subscribed to the Google Groups "nodejs" 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/groups/opt_out.
