TypeError: 'bool' object is not callable while creating custom thread pool

Question

I want to create a custom thread pool for having more control over the code for future needs. So far I haven't been able to write something functional. I want the threads to work separately from the main interpreter process. I don't need multi-core advantage. Threads(Worker) should listen for a change in queue size and run execute on the passed job. I cannot make this code work. Does anybody see any solution to make this work?

import queue
from threading import Thread
import time
import random

class Worker(Thread):
#----------------------------------------------------------
    def __init__(self,queue,x):
        Thread.__init__(self)
        self.run = True
        self.queue = queue
        self.x = x
#----------------------------------------------------------
    def run(self):
        while self.run:
            while not self.queue.empty():
                job = self.queue.get()
                print("Starting", job, self.x)
                job.execute()
                time.sleep(0.1)
                self.queue.task_done()
            time.sleep(0.1)

class TestJob:
    def __init__(self,x):
        self.x = x

    def execute(self):
        print(f"Num {self.x}")

class DownloadManager:
    def __init__(self,numOfThread):
        self.jobQueue = queue.Queue()
        self.numOfThread = numOfThread
        self.threadList = [Worker(self.jobQueue, x) for x in range(0, self.numOfThread)]
        [x.start() for x in self.threadList]
        print("End of init")

    def addJob(self,job):
        self.jobQueue.put(job)

dm = DownloadManager(2)

for x in range(0,10):
    job = TestJob(x)
    dm.addJob(job)

print("After adding all jobs")
input("Waiting for enter")
print("Done")

CONSOLE OUTPUT

Exception in thread Thread-1:
End of init
Traceback (most recent call last):
After adding all jobs
  File "C:\Users\User\AppData\Local\Programs\Python\Python37\lib\threading.py", line 917, in _bootstrap_inner
    self.run()
TypeError: 'bool' object is not callable

Waiting for enterException in thread Thread-2:
Traceback (most recent call last):
  File "C:\Users\User\AppData\Local\Programs\Python\Python37\lib\threading.py", line 917, in _bootstrap_inner
    self.run()
TypeError: 'bool' object is not callable



Done

My Python version is 3.7.2.

Gino Mempin · Accepted Answer · 2019-06-03 07:17:23Z

3

Your Worker class has 2 attributes for run.

class Worker(Thread):
#----------------------------------------------------------
    def __init__(self,queue,x):
        ...
        self.run = True       
        ...
#----------------------------------------------------------
    def run(self):            
        while self.run:
            ...

One is a boolean (self.run = True) and one is a function (def run(self):).

You can't have both a method and an attribute with the same name.

Based on the error message, self.run() is being called, so run is expected be a function. Try changing the property self.run to some other name (ex. self.is_running).

edited Jun 3, 2019 at 7:17

answered Jun 3, 2019 at 7:09

Gino Mempin

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