I am trying to split a large file (>20GB) in chunks to upload them.

This is my method:

   public List<byte[]> chunkFile() throws IOException {
        File file = new File(backupPath);

        List<byte[]> chunks = new ArrayList<>();

        try (FileInputStream fis = new FileInputStream(file)) {
            byte[] buffer = new byte[1024 * 1024 * 10];

            int bytesRead;

            while ((bytesRead = fis.read(buffer)) > 0) {
                byte[] chunk = new byte[bytesRead];
                System.arraycopy(buffer, 0, chunk, 0, bytesRead);
                chunks.add(chunk);
            }
            return chunks;
        }
    }

It works well to small files (500mb), but when I try with a larger file I am facing this error:

Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Handler dispatch failed: java.lang.OutOfMemoryError: Java heap space] with root cause

java.lang.OutOfMemoryError: Java heap space

I need to split the file in chunks to be able to upload to s3 using multi part file.