如何关闭SuiteScript 2.0的SFTP连接？连接未关闭致服务器连接数超限

I’ve seen this exact connection leak issue pop up for a lot of NetSuite developers using the N/sftp module—great that you got file transfers working, but those lingering connections are a real headache. Let’s break down how to fix this properly.

The Core Problem #

NetSuite’s SFTP connections don’t always auto-close reliably, especially if your script hits an error mid-transfer or runs longer than expected. Those orphaned connections stick around on your SFTP server until it hits its max connection limit, forcing that annoying restart cycle.

The Fix: Always Explicitly Close Connections in finally #

The key rule here is never rely on implicit connection cleanup. You need to manually call connection.disconnect(), and wrap that call in a finally block to ensure it runs whether your transfer succeeds or fails.

Here’s how to adjust your code:

const sftp = require('N/sftp');
const file = require('N/file');

function sendFileToSFTP() {
    let sftpConnection = null;

    try {
        // Create the SFTP connection
        sftpConnection = sftp.createConnection({
            username: 'your-username',
            password: 'your-secure-password', // Consider switching to key auth for better security
            url: 'your-sftp-server-url.com',
            port: 22 // Adjust if your server uses a non-standard port
        });

        // Load your local NetSuite file
        const targetFile = file.load({ id: 12345 }); // Replace with your file ID/path

        // Upload the file
        sftpConnection.upload({
            directory: '/remote/target/directory',
            filename: targetFile.name,
            file: targetFile,
            replaceExisting: true
        });

        log.debug('Success', 'File uploaded to SFTP server');
    } catch (transferError) {
        log.error('SFTP Transfer Failed', transferError.message);
        throw transferError; // Re-throw if you want upstream processes to handle the error
    } finally {
        // Close the connection NO MATTER WHAT
        if (sftpConnection) {
            try {
                sftpConnection.disconnect();
                log.debug('Connection Closed', 'SFTP connection successfully terminated');
            } catch (disconnectError) {
                log.error('Connection Close Failed', disconnectError.message);
                // Even if closing fails, log it and move on—no need to halt here
            }
        }
    }
}

Extra Tips to Prevent Future Leaks #

• Reuse connections instead of creating new ones: If your script transfers multiple files, create one connection at the start, do all transfers, then close it once at the end. Multiple connection creations increase the risk of leaks.
• Optimize script runtime: If your script times out, the finally block might not execute. Keep transfers efficient—batch small files, avoid unnecessary processing mid-transfer, and ensure your script stays under NetSuite’s runtime limits.
• Set server-side idle timeouts: As a safety net, configure your SFTP server to automatically drop idle connections after a set period (e.g., 10 minutes). This will clean up any stray connections that slip through the cracks.
• Switch to key-based authentication: Password auth works, but key-based auth is more secure and some SFTP servers handle key-authenticated connections more cleanly, reducing the chance of orphaned sessions.

Why This Happens #

NetSuite’s garbage collection should theoretically clean up unused connection objects, but in practice, exceptions, timeouts, or edge cases in the N/sftp module can leave connections open on the server side. Explicitly closing in finally eliminates this uncertainty.

内容的提问来源于stack exchange，提问作者Charl