Read multiple files in multiple threads, process and write into a single file

test_thread.py

import codecs
import queue  # or queue in Python 3
import threading
import os

class PrintThread(threading.Thread):
    def __init__(self, queue):
        threading.Thread.__init__(self)
        self.queue = queue

    def printfiles(self, p):
        with open("test.csv", "a") as f:
            f.write(p)
                

    def run(self):
        while True:
            result = self.queue.get()
            print(result)
            self.printfiles(result)
            self.queue.task_done()

class ProcessThread(threading.Thread):
    def __init__(self, in_queue, out_queue):
        threading.Thread.__init__(self)
        self.in_queue = in_queue
        self.out_queue = out_queue

    def run(self):
        while True:
            path = self.in_queue.get()
            result = self.process(path)
            self.out_queue.put(result)
            self.in_queue.task_done()

    def process(self, path):
        # Do the processing job here
        with open(path, "r") as f:
            data = f.read()

        return data

pathqueue = queue.Queue()
resultqueue = queue.Queue()
paths = ["file_1.txt", "file_2.txt", "file_3.txt"]

# output = codecs.open('test.csv', 'a')

# spawn threads to process
for i in range(0, 5):
    t = ProcessThread(pathqueue, resultqueue)
    if i == 1:
        import time
        time.sleep(3)
    t.setDaemon(True)
    t.start()

# spawn threads to print
t = PrintThread(resultqueue)
t.setDaemon(True)
t.start()

# add paths to queue
for path in paths:
    pathqueue.put(path)

# wait for queue to get empty
pathqueue.join()
resultqueue.join()