MimeMessage.writeTo hangs on PipedInputStream.awaitSpace()

Question

Hi all,
I have a multi-threaded app which (amongst other things) creates mail files and writes them to disk. When this app is under heavy load, I get several threads "left behind" which appear to be stuck on the call to awaitSpace() within the PipedInputStream class.
In debug, I notice that this method just loops around forever waiting for input. The problem is that I'm not controlling this. I'm just calling the writeTo(OutputStream) method of the MimeMessage class in JavaMail.
Goes something like this...
FileOutputStream fout = null;
try {
     fout = new FileOutputStream("somefile.txt");
     // Just a normal MimeMessage class initialised elsewhere
     message.writeTo(out);
     fout.flush();
finally {
     if (fout != null) {
          fout.close();
}This obviously works fine, but under heavy load the call to message.writeTo(out); blocks forever.
Not sure if it's a problem with the MimeMessage class or the PipedInputStream class (or my code?).
Anyone seen this behaviour before?
I'm using JDK 1.5.0_04

Answer 1

Can you provide a stack trace for the thread that's stuck in PipedInputStream?
I believe the only time a PipedInputStream is used is when you try to
read data from a message part using getInputStream, but the message
part was created using an object instead of a stream so the JAF
DataContentHandler that converts objects to streams uses writeTo to
write the data into a PipedOutputStream so that you can read if from a
PipedInputStream. If you don't consume the entire stream, the writing
thread and the pipe will be left hanging.
If all you're doing is message.writeTo, I'm not sure why this would happen.