Source:
private void handleRequest(HttpServletRequest request, final HttpServletResponse response) throws ServletException, IOException { final AtomicBoolean moreDataWillBeSent = new AtomicBoolean(true); Subscription sampleSubscription = null; int numberConnections = incrementAndGetCurrentConcurrentConnections(); try { int maxNumberConnectionsAllowed = getMaxNumberConcurrentConnectionsAllowed(); if (numberConnections > maxNumberConnectionsAllowed) { response.sendError(503, "MaxConcurrentConnections reached: " + maxNumberConnectionsAllowed); } else { response.setHeader("Content-Type", "text/event-stream;charset=UTF-8"); response.setHeader("Cache-Control", "no-cache, no-store, max-age=0, must-revalidate"); response.setHeader("Pragma", "no-cache"); final PrintWriter writer = response.getWriter(); sampleSubscription = sampleStream .observeOn(Schedulers.io()) .subscribe(new Subscriber<String>() { @Override public void onCompleted() { logger.error("HystrixSampleSseServlet: ({}) received unexpected OnCompleted from sample stream", getClass().getSimpleName()); moreDataWillBeSent.set(false); } @Override public void onError(Throwable e) { moreDataWillBeSent.set(false); } @Override public void onNext(String sampleDataAsString) { if (sampleDataAsString != null) { try { writer.print("data: " + sampleDataAsString + "\n\n"); if (writer.checkError()) { moreDataWillBeSent.set(false); } writer.flush(); } catch (Throwable t) { moreDataWillBeSent.set(false); } } } }); while (moreDataWillBeSent.get() && !isDestroyed) { try { Thread.sleep(pausePollerThreadDelayInMs); writer.print("ping: \n\n"); if (writer.checkError()) { moreDataWillBeSent.set(false); } writer.flush(); } catch (Throwable t) { moreDataWillBeSent.set(false); } } } } finally { decrementCurrentConcurrentConnections(); if (sampleSubscription != null && !sampleSubscription.isUnsubscribed()) { sampleSubscription.unsubscribe(); } } }

Target:
private void handleRequest(HttpServletRequest request, final HttpServletResponse response) throws ServletException, IOException { final AtomicBoolean moreDataWillBeSent = new AtomicBoolean(true); Subscription sampleSubscription = null; int numberConnections = incrementAndGetCurrentConcurrentConnections(); try { int maxNumberConnectionsAllowed = getMaxNumberConcurrentConnectionsAllowed(); if (numberConnections > maxNumberConnectionsAllowed) { response.sendError(503, "MaxConcurrentConnections reached: " + maxNumberConnectionsAllowed); } else { response.setHeader("Content-Type", "text/event-stream;charset=UTF-8"); response.setHeader("Cache-Control", "no-cache, no-store, max-age=0, must-revalidate"); response.setHeader("Pragma", "no-cache"); final PrintWriter writer = response.getWriter(); sampleSubscription = sampleStream .observeOn(Schedulers.io()) .subscribe(new Subscriber<String>() { @Override public void onCompleted() { logger.error("HystrixSampleSseServlet: ({}) received unexpected OnCompleted from sample stream", getClass().getSimpleName()); moreDataWillBeSent.set(false); } @Override public void onError(Throwable e) { moreDataWillBeSent.set(false); } @Override public void onNext(String sampleDataAsString) { if (sampleDataAsString != null) { try { writer.print("data: " + sampleDataAsString + "\n\n"); if (writer.checkError()) { moreDataWillBeSent.set(false); } writer.flush(); } catch (Exception ex) { moreDataWillBeSent.set(false); } } } }); while (moreDataWillBeSent.get() && !isDestroyed) { try { Thread.sleep(pausePollerThreadDelayInMs); writer.print("ping: \n\n"); if (writer.checkError()) { moreDataWillBeSent.set(false); } writer.flush(); } catch (Exception ex) { moreDataWillBeSent.set(false); } } } } finally { decrementCurrentConcurrentConnections(); if (sampleSubscription != null && !sampleSubscription.isUnsubscribed()) { sampleSubscription.unsubscribe(); } } }