报错1
2017-03-28 10:04:47.438 ERROR 1035 --- [InstanceMonitor] c.n.t.monitor.instance.InstanceMonitor : Could not initiate connection to host, giving up: [{"timestamp":1490666687435,"status":503,"error":"Service Unavailable","message":"MaxConcurrentConnections reached: 5","path":"/hystrix.stream"}]
~/.m2/repository/com/netflix/hystrix/hystrix-metrics-event-stream/1.5.6/hystrix-metrics-event-stream-1.5.6-sources.jar!/com/netflix/hystrix/contrib/requests/stream/HystrixRequestEventsSseServlet.java
public class HystrixRequestEventsSseServlet extends HystrixSampleSseServlet {
private static final long serialVersionUID = 6389353893099737870L;
/* used to track number of connections and throttle */
private static AtomicInteger concurrentConnections = new AtomicInteger(0);
private static DynamicIntProperty maxConcurrentConnections =
DynamicPropertyFactory.getInstance().getIntProperty("hystrix.config.stream.maxConcurrentConnections", 5);
//......
}
~/.m2/repository/com/netflix/hystrix/hystrix-metrics-event-stream/1.5.6/hystrix-metrics-event-stream-1.5.6-sources.jar!/com/netflix/hystrix/contrib/sample/stream/HystrixSampleSseServlet.java
/**
* - maintain an open connection with the client
* - on initial connection send latest data of each requested event type
* - subsequently send all changes for each requested event type
*
* @param request incoming HTTP Request
* @param response outgoing HTTP Response (as a streaming response)
* @throws javax.servlet.ServletException
* @throws java.io.IOException
*/
private void handleRequest(HttpServletRequest request, final HttpServletResponse response) throws ServletException, IOException {
final AtomicBoolean moreDataWillBeSent = new AtomicBoolean(true);
Subscription sampleSubscription = null;
/* ensure we aren't allowing more connections than we want */
int numberConnections = incrementAndGetCurrentConcurrentConnections();
try {
int maxNumberConnectionsAllowed = getMaxNumberConcurrentConnectionsAllowed(); //may change at runtime, so look this up for each request
if (numberConnections > maxNumberConnectionsAllowed) {
response.sendError(503, "MaxConcurrentConnections reached: " + maxNumberConnectionsAllowed);
} else {
/* initialize response */
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();
//since the sample stream is based on Observable.interval, events will get published on an RxComputation thread
//since writing to the servlet response is blocking, use the Rx IO thread for the write that occurs in the onNext
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");
// explicitly check for client disconnect - PrintWriter does not throw exceptions
if (writer.checkError()) {
throw new IOException("io error");
}
writer.flush();
} catch (IOException ioe) {
moreDataWillBeSent.set(false);
}
}
}
});
while (moreDataWillBeSent.get() && !isDestroyed) {
try {
Thread.sleep(pausePollerThreadDelayInMs);
} catch (InterruptedException e) {
moreDataWillBeSent.set(false);
}
}
}
} finally {
decrementCurrentConcurrentConnections();
if (sampleSubscription != null && !sampleSubscription.isUnsubscribed()) {
sampleSubscription.unsubscribe();
}
}
}
报错2
10:45:53.194 INFO [http-nio-9002-exec-393] Caller+0 at org.springframework.cloud.netflix.hystrix.dashboard.HystrixDashboardConfiguration$ProxyStreamServlet.doGet(HystrixDashboardConfiguration.java:165)
-
Proxy opening connection to: http://localhost:9002/hystrix.stream
2017-03-28 10:45:53.209 WARN 1404 --- [o-9002-exec-393] ashboardConfiguration$ProxyStreamServlet : Failed opening connection to http://localhost:9002/hystrix.stream : 503 : HTTP/1.1 503
10:45:53.209 WARN [http-nio-9002-exec-393] Caller+0 at org.springframework.cloud.netflix.hystrix.dashboard.HystrixDashboardConfiguration$ProxyStreamServlet.doGet(HystrixDashboardConfiguration.java:212)
- Failed opening connection to http://localhost:9002/hystrix.stream : 503 : HTTP/1.1 503
2017-03-28 10:45:53.209 WARN 1404 --- [o-9002-exec-391] ashboardConfiguration$ProxyStreamServlet : Failed opening connection to http://localhost:9002/hystrix.stream : 503 : HTTP/1.1 503
10:45:53.209 WARN [http-nio-9002-exec-391] Caller+0 at org.springframework.cloud.netflix.hystrix.dashboard.HystrixDashboardConfiguration$ProxyStreamServlet.doGet(HystrixDashboardConfiguration.java:212)
- Failed opening connection to http://localhost:9002/hystrix.stream : 503 : HTTP/1.1 503
curl一下
➜ ~ curl -i http://localhost:9002/hystrix.stream
HTTP/1.1 503
X-Application-Context: recommend:9002
Content-Type: application/json;charset=UTF-8
Transfer-Encoding: chunked
Date: Tue, 28 Mar 2017 02:48:23 GMT
Connection: close
{"timestamp":1490669303758,"status":503,"error":"Service Unavailable","message":"MaxConcurrentConnections reached: 20","path":"/hystrix.stream"}%
如果出现请求/hystrix.stream一直阻塞，或者报错Unable to connect to Command Metric Stream，表示你没有配置HystrixCommand。
解决方案
hystrix.config.stream.maxConcurrentConnections: 50
