I'm trying to trace some odd behavior of a few processes and ran into a point I'm not sure how to trace past. The hung process, which I attached to using
strace -p showed this:
Process 7926 attached - interrupt to quit read(3,
Okay, so it's waiting for input on fd 3, so I went to check what it is:
$ ls -l /proc/7926/fd/3 lr-x------ 1 user grp 64 Mar 15 10:41 /proc/7926/fd/3 -> pipe:
Okay, so it's a pipe... now the question -- who is the writer of this pipe? I recall that on Linux there is a special feature for unix domain sockets where you can request a file path that starts with a NUL byte to access the "abstract socket namespace" (mentioned here: http://tkhanson.net/cgit.cgi/misc.git/plain/unixdomain/Unix_domain_sockets.html). I'm not sure if there's something similar for pipes that I could take advantage of, but I haven't found anything.
I was hoping a tool like
lsof might help, but I haven't gotten anywhere.