C++ - Process launched from another process is not killed when an initial one is killed

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When one process launches another process in C++ (or any programming language), it creates a parent-child relationship between the two processes. The child process inherits certain attributes from the parent process, and the parent process typically waits for the child process to complete. However, killing the parent process does not automatically terminate the child process. This behavior is by design and is common to most operating systems.

If you want the child process to be terminated when the parent process is killed, you need to handle this explicitly. There are several ways to achieve this:

  1. Use Process Groups:
    You can create a process group and add both the parent and child processes to it. When the parent process is killed, it will send a signal to the process group, which will also terminate the child process. This approach requires platform-specific code to manipulate process groups.

  2. Use Inter-Process Communication (IPC):
    Implement communication between the parent and child processes using IPC mechanisms such as pipes, sockets, or signals. When the parent process is killed, it can send a termination signal or message to the child process, instructing it to exit gracefully.

  3. Use Process IDs (PID):
    The parent process can keep track of the child process's PID and periodically check if the child process is still alive. If the parent process is killed, it can send a signal to the child process to terminate before exiting.

  4. Use a Wrapper Process:
    Create a wrapper process that launches both the parent and child processes. The wrapper process can wait for the child process to complete, and if the parent process is killed, it can signal the child process to terminate.

It's essential to handle process termination gracefully to avoid resource leaks and ensure the correct termination of all child processes. The method you choose depends on your specific requirements and the platform you are working on.

Remember that terminating a process abruptly can lead to unexpected behavior and may cause data corruption or other issues. Always ensure proper cleanup and handling of termination signals to avoid any adverse effects.