Redis Subscription + Rails ActionController::Live hangs

Question

In a single controller of a simple Rails 5 app, I have 2 actions ( live and test ), both using ActionController::Live . live goes through a loop and write random data to response.stream.write without any issues. It works.

In test however, I am using Redis.subscribe. Here is the action code:

        def test
            response.headers['Content-Type'] = 'text/event-stream'

            redis = Redis.new

                redis.subscribe_with_timeout(30, "abc") do |on|
                    on.message do |event, data|
                        puts data
                        response.stream.write data
                    end
                end
        rescue IOError
            # ignore
        ensure
            redis.quit
            response.stream.close
        end

The test method however doesn't work as expected. This is what happens:

I start the app and hit the test endpoint with curl . Curl stops waiting for data as expected. Then in redis-cli I send a message to the abc channel. Immediately I see my message in the rails app window ( puts data ) and I see this in curl:

HTTP/1.1 200 OK
Content-Type: text/event-stream
Cache-Control: no-cache
X-Request-Id: 25df052d-e3f2-4327-9a97-088e702460fa
X-Runtime: 2.709001
Transfer-Encoding: chunked

But while the all the consequent messages from redis-cli are printed on the rails side, they are not received by curl until the timeout is over (30 seconds in subscribe_with_timeout ).

I am running Puma, have looked and implemented at all Stackoverflow answers regarding concurreny, heartbeat threads and more with no luck.

Answer 1

经过多次挖掘后，结果发现你需要一个新的行"\\n" ，这些行会在response.stream.write的任何内容结束时让它离开缓冲区。