Both processes and threads are independent sequences of execution. The typical difference is that threads (of the same process) run in a shared memory space, while processes run in separate memory spaces.
lsof | grep 'DEL.lib'
lsof | grep 'DEL.lib' | sort -k1,1 -u
pour la libc : lsof | grep 'DEL'|grep libc-2.13.so|sort -k1,1 -u