Staging
v0.5.1
v0.5.1
https://github.com/python/cpython
Tip revision: 74f4bd53e03ded8408bcc2de67cf0f5a4ac5b1a1 authored by Barry Warsaw on 23 February 2012, 15:59:38 UTC
Bump some more copyright years (as per PEP 101), since this is the first
Bump some more copyright years (as per PEP 101), since this is the first
Tip revision: 74f4bd5
find.py
# A parallelized "find(1)" using the thread module.
# This demonstrates the use of a work queue and worker threads.
# It really does do more stats/sec when using multiple threads,
# although the improvement is only about 20-30 percent.
# (That was 8 years ago. In 2002, on Linux, I can't measure
# a speedup. :-( )
# I'm too lazy to write a command line parser for the full find(1)
# command line syntax, so the predicate it searches for is wired-in,
# see function selector() below. (It currently searches for files with
# world write permission.)
# Usage: parfind.py [-w nworkers] [directory] ...
# Default nworkers is 4
import sys
import getopt
import string
import time
import os
from stat import *
import thread
# Work queue class. Usage:
# wq = WorkQ()
# wq.addwork(func, (arg1, arg2, ...)) # one or more calls
# wq.run(nworkers)
# The work is done when wq.run() completes.
# The function calls executed by the workers may add more work.
# Don't use keyboard interrupts!
class WorkQ:
# Invariants:
# - busy and work are only modified when mutex is locked
# - len(work) is the number of jobs ready to be taken
# - busy is the number of jobs being done
# - todo is locked iff there is no work and somebody is busy
def __init__(self):
self.mutex = thread.allocate()
self.todo = thread.allocate()
self.todo.acquire()
self.work = []
self.busy = 0
def addwork(self, func, args):
job = (func, args)
self.mutex.acquire()
self.work.append(job)
self.mutex.release()
if len(self.work) == 1:
self.todo.release()
def _getwork(self):
self.todo.acquire()
self.mutex.acquire()
if self.busy == 0 and len(self.work) == 0:
self.mutex.release()
self.todo.release()
return None
job = self.work[0]
del self.work[0]
self.busy = self.busy + 1
self.mutex.release()
if len(self.work) > 0:
self.todo.release()
return job
def _donework(self):
self.mutex.acquire()
self.busy = self.busy - 1
if self.busy == 0 and len(self.work) == 0:
self.todo.release()
self.mutex.release()
def _worker(self):
time.sleep(0.00001) # Let other threads run
while 1:
job = self._getwork()
if not job:
break
func, args = job
apply(func, args)
self._donework()
def run(self, nworkers):
if not self.work:
return # Nothing to do
for i in range(nworkers-1):
thread.start_new(self._worker, ())
self._worker()
self.todo.acquire()
# Main program
def main():
nworkers = 4
opts, args = getopt.getopt(sys.argv[1:], '-w:')
for opt, arg in opts:
if opt == '-w':
nworkers = string.atoi(arg)
if not args:
args = [os.curdir]
wq = WorkQ()
for dir in args:
wq.addwork(find, (dir, selector, wq))
t1 = time.time()
wq.run(nworkers)
t2 = time.time()
sys.stderr.write('Total time %r sec.\n' % (t2-t1))
# The predicate -- defines what files we look for.
# Feel free to change this to suit your purpose
def selector(dir, name, fullname, stat):
# Look for world writable files that are not symlinks
return (stat[ST_MODE] & 0002) != 0 and not S_ISLNK(stat[ST_MODE])
# The find procedure -- calls wq.addwork() for subdirectories
def find(dir, pred, wq):
try:
names = os.listdir(dir)
except os.error, msg:
print repr(dir), ':', msg
return
for name in names:
if name not in (os.curdir, os.pardir):
fullname = os.path.join(dir, name)
try:
stat = os.lstat(fullname)
except os.error, msg:
print repr(fullname), ':', msg
continue
if pred(dir, name, fullname, stat):
print fullname
if S_ISDIR(stat[ST_MODE]):
if not os.path.ismount(fullname):
wq.addwork(find, (fullname, pred, wq))
# Call the main program
main()