未找到 PDF 标头签名异步

如何解决未找到 PDF 标头签名异步

异步不适用的时候，这段代码没有问题，但是加了异步(@Async)操作后偶尔会出现问题； 错误是 reader = new PdfReader(pdfInputStream);

@Async
public static void pdfAddWaterMark(InputStream pdfInputStream,Image image,bufferedoutputstream bos){
        PdfReader reader = null;
        pdfstamper stamper = null;
        try {
            reader = new PdfReader(pdfInputStream);
            stamper = new pdfstamper(reader,bos);
            int total = reader.getNumberOfPages();
            PdfContentByte content;           
            for (int i = 0; i < total; i++) {               
                content = stamper.getoverContent(i + 1);               
                image.scaletoFit(450,450);
                image.setAbsolutePosition(60,150);
                content.addImage(image);
            }
        } catch (IOException | DocumentException e) {
            e.printstacktrace();           
        }finally {
            try {
                stamper.close();
                reader.close();
            } catch (Exception e) {
                e.printstacktrace();               
            }
        }
    }