Failed to launch wda because of "Couldn't start port forwarding on port 8100. Please provide a different port using 'wdaLocalPort' capability" without delete session

This issue happened the current master. 1.14.2 worked.

The problem

Appium fails to create a new session with useNewWDA after the first launching on a real device.

I mean:

1. send a create session with useNewWDA: true
   • ok
2. send a create session with useNewWDA: true
   • without deleteSession before this
   • failed because of remaining port 8100 which was used by 1
   • I guessed iproxy class failed to release 8100 port in quite()
     • https://github.com/appium/appium-xcuitest-driver/blob/master/lib/wda/iproxy.js#L42-L48

[debug] [BaseDriver] Event 'wdaStartFailed' logged at 1566837388273 (01:36:28 GMT+0900 (Japan Standard Time))
[debug] [XCUITest] Unable to launch WebDriverAgent because of xcodebuild failure: Couldn't start port forwarding on port 8100. Please provide a different port using 'wdaLocalPort' capability. Make sure you follow the tutorial at https://github.com/appium/appium-xcuitest-driver/blob/master/docs/real-device-config.md. Try to remove the WebDriverAgentRunner application from the device if it is installed and reboot the device.
[XCUITest] Quitting and uninstalling WebDriverAgent
[XCUITest] Shutting down sub-processes
[debug] [XCUITest] Removing WDA application from device
[XCUITest] Error: Unable to launch WebDriverAgent because of xcodebuild failure: Couldn't start port forwarding on port 8100. Please provide a different port using 'wdaLocalPort' capability. Make sure you follow the tutorial at https://github.com/appium/appium-xcuitest-driver/blob/master/docs/real-device-config.md. Try to remove the WebDriverAgentRunner application from the device if it is installed and reboot the device.
[XCUITest]     at quitAndUninstall (/Users/kazu/GitHub/appium-xcuitest-driver/lib/driver.js:505:15)
[debug] [XCUITest] Not clearing log files. Use `clearSystemFiles` capability to turn on.
[debug] [BaseDriver] Event 'newSessionStarted' logged at 1566837388558 (01:36:28 GMT+0900 (Japan Standard Time))
[debug] [W3C] Encountered internal error running command: Error: Unable to launch WebDriverAgent because of xcodebuild failure: Couldn't start port forwarding on port 8100. Please provide a different port using 'wdaLocalPort' capability. Make sure you follow the tutorial at https://github.com/appium/appium-xcuitest-driver/blob/master/docs/real-device-config.md. Try to remove the WebDriverAgentRunner application from the device if it is installed and reboot the device.
[debug] [W3C]     at quitAndUninstall (/Users/kazu/GitHub/appium-xcuitest-driver/lib/driver.js:505:15)
[HTTP] <-- POST /wd/hub/session 500 1716 ms - 1293

Another error in step2

[debug] [XCUITest] Killing running processes 'xcodebuild.*242bfcc998fd156df0bd0ad1dde8ab8e0a032114' for the device 242bfcc998fd156df0bd0ad1dde8ab8e0a032114...
[XCUITest] xcodebuild exited with code '75' and signal 'null'
[debug] [XCUITest] 'pgrep -ifn xcodebuild.*242bfcc998fd156df0bd0ad1dde8ab8e0a032114' didn't detect any matching processes. Return code: 1
uncaughtException: listen EADDRINUSE: address already in use :::8100
Error: listen EADDRINUSE: address already in use :::8100
    at Server.setupListenHandle [as _listen2] (net.js:1279:14)
    at listenInCluster (net.js:1327:12)
    at Server.listen (net.js:1414:7)
    at iProxy.listen [as start] (/Users/kazu/GitHub/appium/node_modules/appium-xcuitest-driver/lib/wda/iproxy.js:33:23)
    at WebDriverAgent.start [as createIProxy] (/Users/kazu/GitHub/appium/node_modules/appium-xcuitest-driver/lib/wda/webdriveragent.js:249:14)
    at WebDriverAgent.createIProxy [as launch] (/Users/kazu/GitHub/appium/node_modules/appium-xcuitest-driver/lib/wda/webdriveragent.js:228:28)
[debug] [XCUITest] Successfully updated '/Users/kazu/GitHub/appium/node_modules/appium-webdriveragent/WebDriverAgent.xcodeproj/project.pbxproj' with bundle id 'com.trident.WebDriverAgent'
[debug] [XCUITest] Generating xcode config file for orgId '9U4PT397Q4' and signingId 'iPhone Developer'
[debug] [XCUITest] Writing xcode config file to /var/folders/34/2222sh8n27d6rcp7jqlkw8km0000gn/T/2019727-20152-xx57uh.t0rw/appium-temp.xcconfig

Environment

• Appium version (or git revision) that exhibits the issue: master (xcuitest-driver was 7f3e52f03b9726eba8a6173de09db5644a3998f9)
• Last Appium version that did not exhibit the issue (if applicable): 1.14.2
• Desktop OS/version used to run Appium: macOS 10.14.6
• Node.js version (unless using Appium.app|exe): 10.16.0
• Npm or Yarn package manager: npm
• Mobile platform/version under test:
• Real device or emulator/simulator: real device
• Appium CLI or Appium.app|exe:

Details

https://github.com/appium/appium-xcuitest-driver/blob/master/lib/wda/iproxy.js#L42-L48 has regression? (I haven’t dug much yet)

Link to Appium logs

[cosminstirbu]

With the .NET client you can use:

private static int GetAvailablePort()
        {
            var listener = new TcpListener(IPAddress.Loopback, 0);

            listener.Start();
            int port = ((IPEndPoint)listener.LocalEndpoint).Port;
            listener.Stop();

            return port;
        }

I’m sure something similar can be done for the other clients as well (Java, etc)

[umutuzgur]

@KazuCocoa We should just do random port allocation. That would fix the wdaLocalPort issue