Скачать или смотреть How to End a Process Midway in Your Python Script

Learn how to manage subprocesses in Python to avoid waiting for processes to complete, enhancing automation and efficiency in your scripts.
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This video is based on the question https://stackoverflow.com/q/67180924/ asked by the user 'ATN' ( https://stackoverflow.com/u/9263456/ ) and on the answer https://stackoverflow.com/a/67181007/ provided by the user 'Almog-at-Nailo' ( https://stackoverflow.com/u/13354437/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to End a Process Midway in Your Python Script

If you've ever worked with Python to automate tasks, you might have encountered a common challenge: your script waits for certain external programs or processes to finish before moving on to the next step. This becomes particularly problematic when using applications like VNC Viewer, where you may want to establish multiple connections quickly without the script stalling. Let’s explore how to solve this issue effectively.

The Problem

In the context of your script, you are utilizing the subprocess.run method to open VNC Viewer using a command that connects to a host. However, the behavior of this method is that it waits for the VNC window to be closed before continuing execution. This halts your automation process, making it inefficient, especially when multiple connections are involved.

Key Points

The goal is to prevent your script from waiting for the VNC Viewer to finish.

There are two main solutions: not waiting at all or closing the connection after a specific time.

The Solution

Using subprocess.run with a Timeout

One effective way to manage subprocesses without waiting indefinitely is by using the timeout feature of the subprocess.run method. Here’s how you can implement this in your script:

Include the timeout Parameter: This will allow the subprocess to be forcibly ended after a specified period.

Handle Exceptions: Since using a timeout may raise a TimeoutExpired exception, you’ll want to wrap your call in a try and except block.

Example Code Adjustment

Here’s how you can update the relevant part of your code:

[[See Video to Reveal this Text or Code Snippet]]

Explanation of the Code:

timeout=5: The VNC Viewer will be forcibly terminated 5 seconds after it starts if it has not closed naturally.

try-except Block: This structure allows your script to handle a timeout gracefully without crashing. If the process doesn’t finish in time, the script will output a message and move to the next host.

Conclusion

By implementing a timeout in your subprocess.run call, you can enhance the efficiency of your Python automation script significantly. This also provides you with the flexibility to manage external processes without the risk of getting stuck, ensuring that your script proceeds smoothly through all tasks.

Now you can explore various connections using VNC Viewer without waiting unnecessarily, optimizing your overall workflow. Happy coding!