The following forum message was posted by xl600sf at http://sourceforge.net/projects/pydev/forums/forum/293649/topic/4428686:
I removed asyncore from the design in place of simple UDP socket I/O. I found
that the debugger exhibits the same behavior in freezing my I/O thread as it
did when the I/O thread was asyncore based. It appears that socket I/O doesn't
cooperate very well with the PyDev debugger when the socket is threaded and
receives data (PyDev 1.6.5). Endless searches on the web have not yeilded any
clues as to why though.
Moving the socket I/O into the main thread seems to have cured the problem.
But that doesn't extend well into larger multi-socket programming under PyDev.