Update IOSDeviceManager.ts

[erdncyz]

During port selection, even if a port appears to be available, it may later be used by another process. In particular, race conditions can occur when ports such as wdaLocalPort or mjpegServerPort are being used simultaneously by another process.

Improvements Made:

Port Usage Control: Functions getFreePortWithCheck and getUnusedPort were added to more accurately check whether ports are available. This is an important step to prevent port conflicts. Safe Port Selection: By using getUnusedPort, safe port selection is ensured for wdaLocalPort and mjpegServerPort. Error Handling and Logging: Parts related to checking port availability and logging errors have been improved. With this code, the risk of port conflicts has been reduced, and port management is now handled in a more reliable way.

#1340

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Name	Status	Preview	Comments	Updated (UTC)
appium-device-farm-bre4	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Sep 25, 2024 9:58am

[saikrishna321]

@erdncyz This will still not help solve the issue.

When the server starts we pick all the devices and get a freeport and assign to the device object. At the time of assigning the port is available, issue comes up with the session creation happens. At this time the port is already picked by some other process.

Fix: During session creation for iOS you need to check if the port is free, if not get another free port and re-assign to the device object.

[erdncyz]

Hi @saikrishna321 @SrinivasanTarget @sudharsan-selvaraj ,

ı change my code for your comment @saikrishna321 can you check again please.

1. getFreePortWithCheck function:
   Purpose: This function finds a free, unused port on the system.
   How it works:
   It creates a TCP server (net.createServer()) and listens on port 0. When you pass 0 as the port number, the system automatically selects a free port for you.
   Once the server starts listening, it retrieves the port that was assigned by the system (using server.address().port), and then immediately closes the server (server.close()), meaning it no longer holds onto that port.
   The port number is then returned as a result via a promise.
   Why unref() is used: server.unref() prevents the server from keeping the Node.js process alive. This is useful to ensure that even if the server is open briefly, it won’t prevent the program from exiting if there is no other work left to do.
2. checkIfPortIsAvailable function:
   Purpose: This function checks whether a specific port is available (i.e., not already being used by another process).
   How it works:
   It tries to create a TCP server that listens on the specified port.
   If the server successfully starts listening on the port, it means the port is available, and the function resolves to true.
   If there is an error while attempting to listen (because another process is already using the port), it catches the error and resolves to false, indicating that the port is in use.
   After determining the port’s availability, the server is immediately closed (tester.close()), regardless of whether the port was available or not.
   Why this is important: Since the system might assign an available port, but by the time you use it, another process could have taken it, this function ensures that the port is still available at the moment you need it.
3. getUnusedPortAtSessionCreation function:
   Purpose: This function combines the other two functions to continuously find and verify an available port, ensuring it's not being used by another process.