SDM BindException: Address already in use

[niloc132]

GWT version: 2.11
Browser (with version): any
Operating System: Linux/Mac (have not tested Windows

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Description

The JettyLauncher has a specific flag passed to Jetty to ensure that SO_REUSEADDR is set, but the SDM code server explicitly disables this, for reasons that are unclear to me. This flag allows a port that was recently used and the browser hasn't yet stopped connecting to to be reused by a new process.

Steps to reproduce

1. Start any GWT sample with SDM, for example ant devmode in the Hello sample
2. Open a browser and connect, wait for the page to load
3. Stop SDM, and quickly start it again - as if some class had changed and we needed a new process to replace it.

Expected: SDM starts right away, and a browser can connect
Actual: SDM fails on startup with an error:

     [java] java.io.IOException: Failed to bind to /127.0.0.1:9876
     [java]     at org.eclipse.jetty.server.ServerConnector.openAcceptChannel(ServerConnector.java:349)
     [java]     at org.eclipse.jetty.server.ServerConnector.open(ServerConnector.java:310)
     [java]     at org.eclipse.jetty.server.AbstractNetworkConnector.doStart(AbstractNetworkConnector.java:80)
     [java]     at org.eclipse.jetty.server.ServerConnector.doStart(ServerConnector.java:234)
     [java]     at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:73)
     [java]     at org.eclipse.jetty.server.Server.doStart(Server.java:401)
     [java]     at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:73)
     [java]     at com.google.gwt.dev.codeserver.WebServer.start(WebServer.java:138)
     [java]     at com.google.gwt.dev.codeserver.CodeServer.start(CodeServer.java:162)
     [java]     at com.google.gwt.dev.codeserver.CodeServer.main(CodeServer.java:104)
     [java]     at com.google.gwt.dev.codeserver.CodeServer.main(CodeServer.java:55)
     [java]     at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
     [java]     at java.base/java.lang.reflect.Method.invoke(Method.java:580)
     [java]     at com.google.gwt.dev.shell.SuperDevListener.runCodeServer(SuperDevListener.java:112)
     [java]     at com.google.gwt.dev.shell.SuperDevListener.start(SuperDevListener.java:91)
     [java]     at com.google.gwt.dev.DevMode.ensureCodeServerListener(DevMode.java:666)
     [java]     at com.google.gwt.dev.DevModeBase.doStartup(DevModeBase.java:785)
     [java]     at com.google.gwt.dev.DevMode.doStartup(DevMode.java:551)
     [java]     at com.google.gwt.dev.DevModeBase.startUp(DevModeBase.java:888)
     [java]     at com.google.gwt.dev.DevModeBase.run(DevModeBase.java:705)
     [java]     at com.google.gwt.dev.DevMode.main(DevMode.java:432)
     [java] Caused by: java.net.BindException: Address already in use
     [java]     at java.base/sun.nio.ch.Net.bind0(Native Method)
     [java]     at java.base/sun.nio.ch.Net.bind(Net.java:565)
     [java]     at java.base/sun.nio.ch.ServerSocketChannelImpl.netBind(ServerSocketChannelImpl.java:344)
     [java]     at java.base/sun.nio.ch.ServerSocketChannelImpl.bind(ServerSocketChannelImpl.java:301)
     [java]     at java.base/sun.nio.ch.ServerSocketAdaptor.bind(ServerSocketAdaptor.java:89)
     [java]     at org.eclipse.jetty.server.ServerConnector.openAcceptChannel(ServerConnector.java:344)
     [java]     ... 20 more

Known workarounds

Stop the browser, so that it releases its end of the socket connection, which will free up the port, or wait long enough for the connection to time out.

Links to further discussions

See https://stackoverflow.com/a/3233022/860630 for a good summary of what SO_REUSEADDR does, why it makes sense here.