Thread won't run in background?

Question

When I call my_batch.run_jobs(), my thread does not run in the background. Instead, it runs synchronously by waiting for the method to finish running.

For context, I am calling this method from within a .py file, and the method is within a class. When I run the same functions outside of this file/class, it runs in the background just fine.

# package_name/module_name.py


class BaseModel(Model):
    class Meta:
        database = get_db()


class Batch(BaseModel):

    def run_jobs():
        
        def sleeper():
            sleep(999)
        
        t = threading.Thread(target=sleeper)
        #t.daemon = True #tried with/ without
        t.start()

for example

my_batch = Batch()
my_batch.run_jobs()
#doesn't print until line above finishes
print("in progress")

Answer 1

I updated your code for testing. It seems to run as expected.

import time, threading

class BaseModel(): pass
#    class Meta:
#        database = get_db()

class Batch(BaseModel):

    def run_jobs(self):
        
        def sleeper(): # runs in background thread
            for t in range(10):
               print('<sleeper>', t)
               time.sleep(.9)
        
        t = threading.Thread(target=sleeper)
        t.start()
        
        # this runs same time as background thread (sleeper)
        for t in range(10):
           print('<rj>', t)
           time.sleep(.8)
                
mybatch = Batch()
mybatch.run_jobs()  # runs in main thread

# this loop runs after run_jobs completes
for t in range(5):
   print('<main>', t)
   time.sleep(1)

Output

<sleeper> 0
<rj> 0
<rj> 1
<sleeper> 1
<rj> 2
<sleeper> 2
<rj> 3
<sleeper> 3
<rj> 4
<sleeper> 4
<rj> 5
<sleeper> 5
<rj> 6
<sleeper> 6
<rj> 7
<sleeper> 7
<rj> 8
<rj> 9
<sleeper> 8
<main> 0
<sleeper> 9
<main> 1
<main> 2
<main> 3
<main> 4

--- Update ---

Here is the same code split into modules:

-- mike.py

import time, threading

class BaseModel(): pass
#    class Meta:
#        database = get_db()

class Batch(BaseModel):

    def run_jobs(self):
        
        def sleeper(): # runs in background thread
            for t in range(10):
               print('<sleeper>', t)
               time.sleep(.9)
        
        t = threading.Thread(target=sleeper)
        t.start()
        
        # this runs same time as background thread (sleeper)
        for t in range(10):
           print('<rj>', t)
           time.sleep(.8)

-- threadchk.py (main script)

import mike
import time, threading
    
mybatch = mike.Batch()
mybatch.run_jobs()  # runs in main thread

# this loop runs after method completes
for t in range(5):
   print('<main>', t)
   time.sleep(1)

Output is the same as previous run