Stdio Transport Processes Not Terminating, Causing Multiple Running Instances

[alifawadhassan]

When using the Stdio transport, server processes don't terminate after requests complete. Each new request spawns another process, causing resource leaks.

We patched the vendor files with a cleanup routine that forcibly kills the subprocess:

Added getter to "/vendor/php-mcp/client/src/Client.php":

public function getTransport(): ?TransportInterface {
    return $this->transport;
}

Added getter to "/vendor/php-mcp/client/src/Transport/Stdio/StdioClientTransport.php":

public function getProcess(): ?Process {
    return $this->process;
}

Used SIGKILL in the finally block of our request wrapper:

finally {
    if (isset($stdioClient)) {
        $transport = $stdioClient->getTransport();

        if ($transport instanceof \PhpMcp\Client\Transport\Stdio\StdioClientTransport) {
            $process = $transport->getProcess();
            if ($process && $process->isRunning()) {
                $process->terminate(SIGKILL); // Forcibly terminate
            }
        }

        $stdioClient->disconnect();
        return $response;
    }
}