Investigate WebSocketOverHTTP2Test.testServerConnectionClose()

[sbordet]

Jetty version
10.0.x

Description
The test passes, but sometimes this NPE happens:

2020-02-26 09:47:47.528:INFO:oejs.Server:main: jetty-10.0.0-SNAPSHOT; built: unknown; git: ; jvm 11.0.6+10
2020-02-26 09:47:47.530:INFO:oejsh.ContextHandler:main: Started o.e.j.s.ServletContextHandler@aafcffa{/,null,AVAILABLE}
2020-02-26 09:47:47.530:INFO:oejs.AbstractConnector:main: Started ServerConnector@20b12f8a{HTTP/1.1, (http/1.1, h2c)}{0.0.0.0:41843}
2020-02-26 09:47:47.535:INFO:oejus.SslContextFactory:main: x509=X509@6955cb39(1,h=[],w=[]) for Server@235a0c16[provider=null,keyStore=file:///home/simon/opensource/jetty/jetty10.0/jetty-websocket/websocket-jetty-tests/src/test/resources/keystore.p12,trustStore=null]
2020-02-26 09:47:47.539:INFO:oejs.AbstractConnector:main: Started ServerConnector@54a67a45{SSL, (ssl, alpn, http/1.1, h2)}{0.0.0.0:38253}
2020-02-26 09:47:47.539:INFO:oejs.Server:main: Started Server@5ddea849{STARTING}[10.0.0-SNAPSHOT,sto=0] @3388ms
2020-02-26 09:47:47.540:WARN:oejusS.config:main: Trusting all certificates configured for Client@6b7906b3[provider=null,keyStore=null,trustStore=null]
2020-02-26 09:47:47.541:WARN:oejusS.config:main: No Client EndPointIdentificationAlgorithm configured for Client@6b7906b3[provider=null,keyStore=null,trustStore=null]
2020-02-26 09:47:47.555:WARN:oejs.HttpChannel:server-159: /ws/connectionClose
java.lang.NullPointerException
	at org.eclipse.jetty.http2.server.HttpTransportOverHTTP2.prepareUpgrade(HttpTransportOverHTTP2.java:324)
	at org.eclipse.jetty.http2.server.HTTP2ServerConnection$ServerHttpChannelOverHTTP2.checkAndPrepareUpgrade(HTTP2ServerConnection.java:382)
	at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:494)
	at org.eclipse.jetty.server.HttpChannel.run(HttpChannel.java:327)
	at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.runTask(EatWhatYouKill.java:336)
	at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.doProduce(EatWhatYouKill.java:313)
	at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.tryProduce(EatWhatYouKill.java:171)
	at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.produce(EatWhatYouKill.java:135)
	at org.eclipse.jetty.http2.HTTP2Connection.produce(HTTP2Connection.java:200)
	at org.eclipse.jetty.http2.HTTP2Connection.onFillable(HTTP2Connection.java:147)
	at org.eclipse.jetty.http2.HTTP2Connection$FillableCallback.succeeded(HTTP2Connection.java:370)
	at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:103)
	at org.eclipse.jetty.io.ChannelEndPoint$2.run(ChannelEndPoint.java:117)
	at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.runTask(EatWhatYouKill.java:336)
	at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.doProduce(EatWhatYouKill.java:313)
	at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.tryProduce(EatWhatYouKill.java:171)
	at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.produce(EatWhatYouKill.java:135)
	at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:823)
	at org.eclipse.jetty.util.thread.QueuedThreadPool$Runner.run(QueuedThreadPool.java:945)
	at java.base/java.lang.Thread.run(Thread.java:834)
2020-02-26 09:47:47.556:INFO:oejs.Server:main: Stopped Server@5ddea849{STOPPING}[10.0.0-SNAPSHOT,sto=0]
2020-02-26 09:47:47.556:INFO:oejs.AbstractConnector:main: Stopped ServerConnector@20b12f8a{HTTP/1.1, (http/1.1, h2c)}{0.0.0.0:0}
2020-02-26 09:47:47.557:INFO:oejs.AbstractConnector:main: Stopped ServerConnector@54a67a45{SSL, (ssl, alpn, http/1.1, h2)}{0.0.0.0:0}
2020-02-26 09:47:47.557:INFO:oejsh.ContextHandler:main: Stopped o.e.j.s.ServletContextHandler@aafcffa{/,null,UNAVAILABLE}

[sbordet]

@lachlan-roberts as per our discussion, I would like to understand better why the NPE happens (what race triggers it) before a fix is attempted. Then maybe the fix is the same, but at least we know what it is.

Please document in this issue what is the race.

[lachlan-roberts]

The test was deliberatly closing the endpoint in the middle of the upgrade, this caused the AbstractHandshaker to throw in the call to Response.flushBuffer(); and because of this the UPGRADE_CONNECTION_ATTRIBUTE was never set. When we get to the point where we try to use the upgrade attribute, it is null so we get the NPE.