I am wondering is there something special I need to do for ending a thread job in Flask? Here is the sample code:
from flask import (
Flask, jsonify, render_template, request
)
import threading
import time
import random
app = Flask(__name__)
def task(thread_return):
random_seconds=random.random()
print(f'Start task {threading.current_thread().name} ')
time.sleep(random_seconds*15)
print(f'completed {threading.current_thread().name} ')
thread_return['seconds']= random_seconds*5
thread_return = {'seconds': 0}
@app.route("/", methods=["GET", "POST"])
def index():
if request.method == "GET":
return render_template("index-ajax.html")
val = request.json.get("c_check")
t =threading.Thread(target=task, args=(thread_return,), daemon=True)
if val==1:
print("val1 is ", val)
t.start()
elif val==0:
try:
print('trying to kill thread')
exit_event= threading.Event()
exit_event.set()
except Exception as e:
print(e)
print("val0 is ", val)
return jsonify({"data": {"val": val}})
if __name__ == "__main__":
app.run(host="127.0.0.1", port=5000, debug=True)
I've tried incorporating several examples I saw online that wraps the task function inside a class, but it didn't work, namely: Exit Thread Gracefully
I like this other example, but I also couldn't get it to work with Flask: How Do You Kill a Python Thread
Thank you for your help.
CodePudding user response:
I was trying multiple rewrites and noticed that the following works. Apparently, I needed to
- declare the threading.event() outside of the route function
- set the exit_event.set() inside the task function to end the task or prevent the task from running
- and modify the task function to better mimic a long or indefinite running task
Perhaps someone else have a more elegant pythonic solution.
from flask import (
Flask, jsonify, render_template, request
)
import threading
import time
import random
app = Flask(__name__)
def task(thread_return):
i=0
while True:
if exit_event.is_set():
print(f'end {threading.current_thread().name} ')
return
i =1
random_seconds=random.random()
print(f'Running task {threading.current_thread().name} {i} sec elapsed')
time.sleep(1)
exit_event= threading.Event()
@app.route("/", methods=["GET", "POST"])
def index():
if request.method == "GET":
return render_template("index-ajax.html")
val = request.json.get("c_check")
exit_event.clear()
t =threading.Thread(target=task, args=(thread_return,), daemon=True)
if val==1:
print("val1 is ", val)
t.start()
elif val==0:
try:
print('trying to end thread')
exit_event.set()
except Exception as e:
print(e)
print("val0 is ", val)
return jsonify({"data": {"val": val}})
if __name__ == "__main__":
app.run(host="127.0.0.1", port=5000, debug=True)