Create thread vs. create process in Linux (both use the clone syscall)

fork.py

from os import fork

print fork()
# clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=...)

thread.py

from threading import Thread
from os import getpid
import ctypes
import sys


SYS_gettid = 186
libc = ctypes.cdll.LoadLibrary('libc.so.6')


def gettid():
    return libc.syscall(SYS_gettid)


def f():
    sys.stdout.write("Thread pid=%d tid=%d\n" % (getpid(), gettid()))
    sys.stdout.flush()


t = Thread(target=f)
t.start()

# clone(child_stack=.., flags=CLONE_VM|CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|CLONE_SYSVSEM|CLONE_SETTLS|CLONE_PARENT_SETTID|CLONE_CHILD_CLEARTID, parent_tidptr=..., tls=..., child_tidptr=...)

sys.stdout.write("Parent pid=%d tid=%d\n" % (getpid(), gettid()))

t.join()