Process Multiple onCreated events parallelly in python watchdog

Question

I am trying to detect if any new files are created on a directory ; if created I want to process it (takes 10 minutes to give output), in the mean time other new files would also be created in the folder.

How do i register the watchdog's oncreated with multiprocess such that instead of waiting for one file to be completed it spawns a new process everytime a file it created.

import time
import datetime
from watchdog.observers import Observer
from watchdog.events import PatternMatchingEventHandler
import multiprocessing as mp
def on_created(event):
    print(f"hey, {event.src_path} has been created!")
    time.sleep(10)
    doProcessing(event.src_path)
    print(f"hey for {event.src_path}")

if __name__ == "__main__":
    patterns = "*"
    ignore_patterns = ""
    ignore_directories = False
    case_sensitive = True
    my_event_handler = PatternMatchingEventHandler(patterns, ignore_patterns, ignore_directories, case_sensitive)
    path = "D:\watcher"
    go_recursively = True
    my_observer = Observer()
    my_observer.schedule(my_event_handler, path, recursive=go_recursively)
    my_observer.start()    
    my_event_handler.on_created = on_created
    #my_event_handler.on_deleted = on_deleted
    #my_event_handler.on_modified = on_modified
    try:
        while True:
            time.sleep(1)
    except KeyboardInterrupt:
        my_observer.stop()
    my_observer.join()

def doProcessing(filename):
    print("Processing")

user_6138564 · Answer

Sorry for so many commented out portions of the code; in essence pool.apply_async(print_func, (event,)) is what helped solve the problem; once events are pushed into the queue; the process_on_load function iterates through the queue and asynchronously runs the print_func.

# -*- coding: utf-8 -*-
"""
Created on Mon Oct 21 22:02:55 2019

@author: 1009758
"""
import os
import time
import datetime
from watchdog.observers import Observer
from watchdog.events import PatternMatchingEventHandler
import multiprocessing as mp
from multiprocessing import Process
from multiprocessing import Queue
import threading

from multiprocessing import Pool
PROCESSES = mp.cpu_count() - 1
NUMBER_OF_TASKS = 10
class FileLoaderWatchdog(PatternMatchingEventHandler):
    ''' Watches a nominated directory and when a * type  file is 
        moved 

    '''

    def __init__(self, queue, patterns):
        PatternMatchingEventHandler.__init__(self, patterns=patterns)
        self.queue = queue

    def process(self, event):
        '''
        event.event_type
            'modified' | 'created' | 'moved' | 'deleted'
        event.is_directory
            True | False
        event.src_path
            path/to/observed/file
        '''
        self.queue.put(event)

    def on_created(self, event):
        self.process(event)
        now = datetime.datetime.utcnow()
        #print(f"hey for {event.src_path}")
        print ("{0} -- event {1} off the queue ...".format(now.strftime("%Y/%m/%d %H:%M:%S"), event.src_path))


def print_func(event):
    time.sleep(5)
    now = datetime.datetime.utcnow()
    print ("{0} -- Pulling {1} off the queue ...".format(now.strftime("%Y/%m/%d %H:%M:%S"), event.src_path))

def info(title):
    print(title)
    print('module name:', __name__)
    print('parent process:', os.getppid())
    print('process id:', os.getpid())   

def process_load_queue(q):
    '''This is the worker thread function. It is run as a daemon 
       threads that only exit when the main thread ends.

       Args
       ==========
         q:  Queue() object
    '''
    while True:
        if not q.empty():
            #mp.set_start_method('spawn')
            event = q.get()
            pool = Pool(processes=1)
            pool.apply_async(print_func, (event,))
            ##p = Pool(5)
            #p.map(print_func,(event,))
            #print_func(event)
            #info('main line')
            #procs = []
            #proc = Process(target=print_func, args=(event,))
            #procs.append(proc)
            #proc.start()
            #for proc in procs:
             #   proc.join()
            #print ("{0} -- Pulling {1} off the queue ...".format(now.strftime("%Y/%m/%d %H:%M:%S"), event.src_path))
            #time.sleep(5)
           # now2 = datetime.datetime.utcnow()
            #print ("{0} -- Replying {1} off the queue ...".format(now2.strftime("%Y/%m/%d %H:%M:%S"), event.src_path))
        else:
            time.sleep(1)



if __name__ == '__main__':

    # create queue
    watchdog_queue = Queue()


    # Set up a worker thread to process database load


    # setup watchdog to monitor directory for trigger files
    #args = sys.argv[1:]
    patt = ["*"]
    path_watch = "D:\watcher"
    event_handler = FileLoaderWatchdog(watchdog_queue, patterns=patt)
    observer = Observer()
    observer.schedule(event_handler, path=path_watch)
    observer.start()
    #pool=Pool(processes = 1)
    #pool.apply_async(process_load_queue, (watchdog_queue,))
    worker = threading.Thread(target=process_load_queue, args=(watchdog_queue,))

    worker.setDaemon(True)
    worker.start()
    #p = Pool(2)
    #p.map(observer,watchdog_queue)


    #asyncio.run(main())
    try:
        while True:
            time.sleep(2)
    except KeyboardInterrupt:
        observer.stop()
    observer.join()

Process Multiple onCreated events parallelly in python watchdog

1 Answers