For a single-threaded process, you will find all the information
about the state of the process under /proc/pid itself. For a multi-threaded
process, the /proc/pid will have a sub directory called task. This directory
contains contains one sub directory per thread, including the main thread:
/proc/pid/task/tid1, /proc/pid/task/tid2, etc. The main thread has the thread
ID same as the process ID.
The easiest way to find out if a given process is multi threaded
or not is to examine the /proc/pid/task directory. If it contains many
sub directories, its a multi-threaded process. Otherwise, it could be a single
threaded one.
The Number of Threads that processes have can be given using
cat /proc/<PID>/status
Happy Learning :-)
