Using iText 2.1.7 to merge large PDFs

Question

I am using an older version of iText (2.1.7) to merge PDFs. Because that is the last version under the MPL available to me. I cannot change this.

Anyways. I am trying to merge multiple PDFs. Everything seems to work ok, but when I go over about 1500 pages, then the generated PDF fails to open (behaves as if it is corrupted)

This is how I am doing it:

private byte[] mergePDFs(List<byte[]> pdfBytesList) throws DocumentException, IOException {
    Document document = new Document();
    ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
    PdfCopy copy = new PdfCopy(document, outputStream);
    document.open();

    for (byte[] pdfByteArray : pdfBytesList) {
        ByteArrayInputStream readerStream = new ByteArrayInputStream(pdfByteArray);
        PdfReader reader = new PdfReader(readerStream);

        for (int i = 0; i < reader.getNumberOfPages(); ) {
            copy.addPage(copy.getImportedPage(reader, ++i));
        }

        copy.freeReader(reader);
        reader.close();
    }

    document.close();

    return outputStream.toByteArray();
}

Is this the correct approach? Is there anything about this that would hint at breaking when going over a certain amount of pages? There are no exceptions thrown or anything.

Answer 1

For anyone curious, the issue had nothing to do with iText and instead was the code responsible for returning the response from iText.