Using JavaMail I have made a method which sends an email with an attachment. A URL is passed to the method as a parameter, which indicates where to find the attachment. So, if you pass it the URL "http://www.mywebsite.com/doc.pdf", then doc.pdf will be downloaded and attached to the email that goes out.



I run into problems when the specified URL is a particular JSP which dynamically generates a PDF. Not all PDFs, mind you, cause a problem. In most cases, the PDF is retrieved and mailed out as expected. However if the generated PDF exceeds a certain size - and so it takes a few minutes to generate - the Transport.send(message) call hangs indefinitely.



The interesting part is that this problem only occurs when the JSP contains the directive <%@ page isThreadSafe="false" %> (this serializes all requests for the page). If I set this directive to true, the method works just fine. (Unfortunately I can't leave the directive set to true for other reasons.) I am making sure that there is no other access to the JSP going on - only my test program is calling it. Therefore, it seems to me that this method is somehow accessing the JSP twice, but only when the generated PDF is big.



To reiterate, my tests indicate that the retrieving/mailing of the PDF works as expected when:

- the URL indicates a static PDF (or any other type of file), regardless of size

- the PDF-generating JSP - having isThreadSafe set to true - is called, regardless of the generated PDF's size.

- the PDF-generating JSP - having isThreadSafe set to false - is called, and the generated PDF is small (or it doesn't take too much time to generate - not sure which is the exact issue - but it is true that PDF size directly relates to time to generate)



My tests indicate that the method hangs on Transport.send(message) when:

- the PDF-generating JSP - having isThreadSafe set to false - is called, and the generated PDF is big (or it takes too long to generate)



I'm rather puzzled. Below you'll find a snippet of the method containing only the relevant lines of code. If anyone has any pointers or suggestions, I would love to hear them.



Thanks,

Mark

			

			Properties props = new Properties();
			

			props.put("mail.smtp.host", emailIP);
			

			Session session = Session.getInstance(props);
			

			

			MimeMessage message = new MimeMessage(session);
			

			InternetAddress iaFrom = new InternetAddress(from);
			

			message.setFrom(iaFrom);
			

			InternetAddress iaTo = new InternetAddress(to);
			

			message.setSubject(subject);
			

			message.setSentDate(new Date());
			

			// Create the body text
			

			Multipart multipart = new MimeMultipart();
			

			MimeBodyPart mainBodyPart = new MimeBodyPart();
			

			if (body == null) {
			

			mainBodyPart.setText(" ");
			

			}
			

			else {
			

			mainBodyPart.setText(body);
			

			}
			

			// Part two is attachment
			

			URL url = new URL(attachmentUrl);
			

			BodyPart attachmentBodyPart = new MimeBodyPart();
			

			

			DataSource source = new URLDataSource(url);
			

			message.addRecipient(Message.RecipientType.TO, iaTo);
			

			multipart.addBodyPart(mainBodyPart);
			

			attachmentBodyPart.setDataHandler(new DataHandler(source));
			

			attachmentBodyPart.setFileName(attachmentName);
			

			multipart.addBodyPart(attachmentBodyPart);
			

			

			message.setContent(multipart);
			

			

			Transport.send(message);