NodeJS itself keeps file EBUSY on Windows?

Question

I created a simple function to process uploaded files. I'm using multer to process the multipart data into files. Then I use the code below to move the files around, and return data so my webpage knows how to display the images.

It seems that somehow NodeJS keeps the files open itself. I also created a function to remove the files, but this will give me an EBUSY error. If I try to remove through Windows, it says that NodeJS has te file locked. When I restart the NodeJS process and then re-request the delete URL, the file is removed correctly.

Is there some way I can force NodeJS to close the file resources? Or is there some other error in my script that I am missing?

I updated node to version 12.4.0 but this didn't help either.

Processing the uploads:

exports.handleFormNotes = async(req, res, next) => {
    try {
        const configVariables = req.app.get('configVariables');
        const uploadSuffix = req.body.uploadFolderSuffix || '';

        console.log('upload suffix', uploadSuffix);

        if (!req.files.length) {
            return;
        }

        const uploadedFiles = Array();

        var destPath = configVariables['FormNotesUploadDirectory'];
        if (uploadSuffix !== '') 
            destPath = destPath + '/' + uploadSuffix;
        destPath = path.resolve(destPath);

        // mkdirSync returns undefined, so run that first and see if the directory exists second.
        if (!fs.mkdirSync(destPath, { recursive: true }) && !fs.existsSync(destPath)) {
            console.log(destPath, 'does not exist!');
            req.alertHandler.addAlert('Pad om afbeelding op te slaan is niet bereikbaar: ' + destPath, 'danger');
            res.render('error');
            return;
        }

        var baseUrlPath = configVariables['FormNotesUploadDocumentRoot'];
        if (uploadSuffix != null) {
            baseUrlPath = baseUrlPath + '/' + uploadSuffix;
        }

        for(const uploadedFile of req.files) {
            let now = new Date();
            let destFilename = getDateTime() + "_" + uploadedFile.originalname;
            let destFilenameThumb = 'thumb_' + destFilename;

            var fullDestination = path.resolve(destPath + '/' + destFilename);
            var fullDestinationThumb = path.resolve(destPath + '/' + destFilenameThumb);

            console.log('Copy src:', uploadedFile.path, fullDestination);
            fs.copyFileSync(uploadedFile.path, fullDestination);

            var unlinkResult = fs.unlinkSync(uploadedFile.path);
            console.log('Unlink "' + uploadedFile.path + '", result after upload:', unlinkResult);

            var newFileInfo = await sharp(destPath + '/' + destFilename)
                .resize({ width: 120 })
                .toFile(fullDestinationThumb);

            console.log('new file info thumb:', newFileInfo);

            uploadedFiles.push({
                'fullImg': baseUrlPath + '/' + destFilename,
                'thumbImg' : baseUrlPath + '/' + destFilenameThumb,
                'original': uploadedFile.originalname
            });
        }

        // Push to backend
        const data = {
            files: [...uploadedFiles],
            uploadSuffix: uploadSuffix
        };

        // Normally retVal should be the return data from OI. If anything goes wrong, retVal = 'error'
        this.saveAttachment(req, res, data);
        return res.send(data);    
    }
    catch (err) {
        console.log('Error handling from notes:', err);
        req.alertHandler.addAlert('Error handling form notes: ' + err);
        return 'error';
    }
}

Removing the uploads:

exports.rmFormNote = async(req, res, data) => {
    let retVal;

    try {
        const configVariables = req.app.get('configVariables');

        const httpPath = req.query.img;
        console.log('http path:', httpPath);

        // Strip off the document root, but check if they are the same first
        const firstPart = httpPath.substring(0, configVariables['FormNotesUploadDocumentRoot'].length);

        console.log('same?', firstPart, configVariables['FormNotesUploadDocumentRoot']);
        var relPath = httpPath;
        if (firstPart == configVariables['FormNotesUploadDocumentRoot']) {
            relPath = httpPath.substring(configVariables['FormNotesUploadDocumentRoot'].length + 1);
        }

        var parts = relPath.split('/');
        parts[parts.length-1] = 'thumb_' + parts[parts.length-1];
        var thumbPath = parts.join('/');
        thumbPath = path.resolve(configVariables['FormNotesUploadDirectory'] + '/' + thumbPath);

        console.log('thumbpath: ', thumbPath);

        var fullPath = configVariables['FormNotesUploadDirectory'] + '/' + relPath;
        var dest = path.resolve(fullPath);

        console.log('dest: ', dest);


        if (!fs.existsSync(dest)) 
            throw "File not found";

        fs.unlink(dest, (err) => {
            if (err) throw err;
            console.log('File deleted');
        });

        retVal = { result: true };
    }
    catch(err) {
        console.log('Ohnoo', err);

        retVal = { result: false, msg: err };

    }

    return res.send(retVal);
}

Answer 1

Turns out the thumbnail creator sharp was the problem, as stated in this github issue.

I just had to disable the cache, like so:

sharp.cache(false);
var newFileInfo = await sharp(destPath + '/' + destFilename)
    .resize({ width: 120 })
    .toFile(fullDestinationThumb);