[undertow-dev] http/2 server starts dying after rapid refresh

Thu May 28 19:18:26 EDT 2015

Hello,

I'm trying out HTTP/2 with undertow-core in my application, and I see
that I'm able to get the server into a bad state pretty reliably by
refreshing quickly in my browser.  It stops responding to requests and
the CPU usage of the Java process starts to climb towards 100%.

I was able to replicate this in the HTTP/2 example in the latest from
the master branch, by changing the main HttpHandler.  This is what I
put in Http2Server#main(String[]):

  Undertow server = Undertow.builder()
        .setServerOption(UndertowOptions.ENABLE_HTTP2, true)
        .setServerOption(UndertowOptions.ENABLE_SPDY, true)
        .addHttpListener(8080, bindAddress)
        .addHttpsListener(8443, bindAddress, sslContext)
        .setHandler(new HttpHandler() {
          @Override
          public void handleRequest(HttpServerExchange exchange) {
            if (exchange.isInIoThread()) {
              exchange.dispatch(this);
              return;
            }
            exchange.startBlocking();
            exchange.getResponseHeaders().put(
                new HttpString("Content-Type"), "text/html");
            try (BufferedWriter writer = new BufferedWriter(
                new OutputStreamWriter(
                    exchange.getOutputStream(),
                    StandardCharsets.UTF_8))) {
              writer.append("<!DOCTYPE html><html>\n");
              for (int i = 0; i < 100; i++) {
                writer.append(
                    "<link rel=\"stylesheet\" href=\"/" + i + ".css\">\n");
              }
              writer.append("hello");
            } catch (IOException e) {
              e.printStackTrace();
              throw new RuntimeException(e);
            }
          }
        }).build();

Then I go to https://localhost:8443/ in a browser and hold down F5 for
a bit.  I start seeing errors like this:

  java.nio.channels.ClosedChannelException
        at io.undertow.server.protocol.framed.AbstractFramedStreamSinkChannel.write(AbstractFramedStreamSinkChannel.java:396)
        at org.xnio.channels.Channels.writeFinalBasic(Channels.java:961)
        at io.undertow.server.protocol.framed.AbstractFramedStreamSinkChannel.writeFinal(AbstractFramedStreamSinkChannel.java:420)
        at org.xnio.conduits.StreamSinkChannelWrappingConduit.writeFinal(StreamSinkChannelWrappingConduit.java:66)
        at org.xnio.conduits.ConduitStreamSinkChannel.writeFinal(ConduitStreamSinkChannel.java:104)
        at io.undertow.channels.DetachableStreamSinkChannel.writeFinal(DetachableStreamSinkChannel.java:195)
        at io.undertow.server.HttpServerExchange$WriteDispatchChannel.writeFinal(HttpServerExchange.java:1882)
        at io.undertow.io.UndertowOutputStream.writeBufferBlocking(UndertowOutputStream.java:288)
        at io.undertow.io.UndertowOutputStream.close(UndertowOutputStream.java:331)
        at sun.nio.cs.StreamEncoder.implClose(StreamEncoder.java:320)
        at sun.nio.cs.StreamEncoder.close(StreamEncoder.java:149)
        at java.io.OutputStreamWriter.close(OutputStreamWriter.java:233)
        at java.io.BufferedWriter.close(BufferedWriter.java:266)
        at io.undertow.examples.http2.Http2Server$1.handleRequest(Http2Server.java:94)
        at io.undertow.server.Connectors.executeRootHandler(Connectors.java:199)
        at io.undertow.server.HttpServerExchange$1.run(HttpServerExchange.java:774)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at java.lang.Thread.run(Thread.java:745)

In case it helps, I saw a different error in my real (not undertow
example) application when I started seeing the same effects visibly
(site down and CPU climbing to 100%).  Maybe it is the same root cause
but just being caught/logged differently:

  ERROR [2015-05-28 14:23:59,804] org.xnio.nio: XNIO000011: Task
io.undertow.server.protocol.framed.AbstractFramedChannel$2 at 308b5f1f
failed with an exception
  java.lang.IllegalStateException: null
  at io.undertow.server.protocol.framed.AbstractFramedStreamSinkChannel.getBuffer(AbstractFramedStreamSinkChannel.java:523)
~[undertow-core-1.3.0.Beta1-SNAPSHOT.jar:1.3.0.Beta1-SNAPSHOT]
  at io.undertow.server.protocol.framed.AbstractFramedChannel.flushSenders(AbstractFramedChannel.java:496)
~[undertow-core-1.3.0.Beta1-SNAPSHOT.jar:1.3.0.Beta1-SNAPSHOT]
  at io.undertow.server.protocol.framed.AbstractFramedChannel$2.run(AbstractFramedChannel.java:581)
~[undertow-core-1.3.0.Beta1-SNAPSHOT.jar:1.3.0.Beta1-SNAPSHOT]
  at org.xnio.nio.WorkerThread.safeRun(WorkerThread.java:560)
~[xnio-nio-3.3.1.Final.jar:3.3.1.Final]
  at org.xnio.nio.WorkerThread.run(WorkerThread.java:462)
~[xnio-nio-3.3.1.Final.jar:3.3.1.Final]

I see the same behavior in my real application with both undertow-core
1.2.6.Final and 1.3.0.Beta1-SNAPSHOT (the latter installed locally
from source).  I only tried the Http2Server example in the latest
version though.

-Michael