I have a python script which runs a for loop. I made it executable and put it in a cron job.
It posts a few tweets on twitter. For each loop, it sleeps a few seconds with random times.
However, it appears it only runs the very first loop and then stops. Every time, I only got ONE tweet. I could not figure out why.
Here is the core part of the code.
def post_message(url):
d = parse(url)
entries = d.entries
for entry in entries:
str = entry.title
tweet(str)
t = random.randint(start, stop)
time.sleep(t)
This is how I set it in cron.
0 23 * * * /home/demo/post_message.py
It only post the very first one and then stops. I am wondering if the time.sleep function stops the rest loops in cron?
Thanks.
Have you tried to run this python script from shell?
Is there any exception (Like you posted too frequently led the script to a 403 page which keeps the function from finding any appropriate html element) generated in 2nd tweet() function?
Related
I have a python script driving me crazy.
Right now i have a infinite loop that checks a data and get into a function in a specific situation.
while true:
time.sleep(1)
peso = getPeso()
if peso > 900:
processo = multiprocessing.Process(target=processo_automatico)
processo.start()
processo.join()
andare() #this is where it should go after the process.
The function works a lot of times but nondeterministically it hangs at the end of the process (literally finish and hangs there forever. How do i know this? i tried with logs).
So at the beginning I tried to terminate it with exit codes:
processo.join(timeout=10)
if processo.exitcode is None:
errore_cicalino() #this is just a warning for me
processo.kill()
elif processo.exitcode != 0:
errore_cicalino()
processo.kill()
but this never worked. NEVER.
So i tried without the join(). Tried with is_alive().
time.sleep(10)
if processo.is_alive():
processo.terminate()
errore_cicalino()
and even like this, it never entered this if.
This is driving me crazy, i accept the fact that the process could fail but, after the timeout, i should be able to terminate it and carry on with the script.
The script is running on a Raspberry Pi 4 2 GB.
Any idea?
Minimal example:
while True:
time.sleep(10)
processo = multiprocessing.Process(target=processo_automatico)
processo.start()
processo.join()
code randomly hangs at the end of the started process and cannot terminate in any way.
processo_automatico() is a function where the script get a picture from a camera and upload it in a DB thanks to another module.
def processo_automatico():
now = str(datetime.now())
now = now.replace(":", "-")
foto = CAMERA.read_camera()
cv2.imwrite("/var/www/html/" + now + ".png", foto)
DB.insert("/var/www/html/" + now + ".png", peso)
They don't create exceptions and i already tried to add to the end of the function a log info(executed even when the code hangs)
Solved.
What was that?
Well, my focus was on the end of the process while the issue was right at the start.
See the function getPeso()? That one just gets values from the serial.
After a few hours of getting those values the raspberry py just starts to see random values and you gotta reboot to fix it.
I wasn't prepared for that. My function just became a recursive infinite function with no break.
My tip, do not use infinite cycles except if you really need to or at least think if it could get stuck somewhere and check it.
I am trying to use APScheduler to automate a function call. It is supposed to read a date from a website I scrape, and then at a certain time relative to that date call the function (2 minutes before). The code for this portion of the project is here:
for mtp, url, track in zip(mtp_num_final, url_list, race_list):
scheduled_time = datetime.now() + relativedelta(minutes =+ (mtp - 2))
print(scheduled_time.strftime('%m-%d-%Y %I:%M%p'))
scheduler.add_job(two_minute_scrape(url, track, 5), 'date', scheduled_time)
The basic gist of the above code is that race_list and and url_list hold data which the two_minute_scrape function needs. I get the amount of minutes + 2 that I want to wait from mtp num final. When I run this code, the printed out date is correct - it knows exactly when I want to run the code, but then it IMMEDIATELY runs two_minute_scrape instead of waiting for that time. Is there anyway to solve this?
Thanks!
I have written some code to make the turtlebot turn around. The code is working. What I want to know is how fast the turtlebot is running and how I can control it. Forexample, how can I ensure that the turtlebot turns 5 degrees in one minute?
Last part of the question. After pressing Ctrl-C, the turtlebot stops but the script keeps running. Why? and how can I stop that?
this post does not really help.
went through this post .Does that mean that the while loop below runs 5 times a second regardless of the values I put in the for loops? Or does it mean ROS tries its best to make sure that the loop runs 5 times a second to the best of my machine's ability?
Thank you very much.
# 5 HZ
angle = 5
r = rospy.Rate(5);
while not rospy.is_shutdown():
# code to turn
for x in range(0,100):
rospy.loginfo("turn")
turn_cmd.angular.z = radians(angle)
new_angle = (angle + new_angle) % 360
self.cmd_vel.publish(turn_cmd)
r.sleep()
# code to pause
for x in range(0,100):
rospy.loginfo("stop")
turn_cmd.angular.z = radians(0)
self.cmd_vel.publish(turn_cmd)
r.sleep()
def shutdown(self):
# stop turtlebot
rospy.loginfo("Stop turning")
self.cmd_vel.publish(Twist())
rospy.sleep(1)
According to ROS Wiki, the rospy.Rate convenience class makes a best effort to maintain the loop running at the specified frequency by considering the execution time of the loop since the last successful r.sleep(). This means in your case: as long as the code execution time within the loop does not exceed 1/5 seconds, rospy.Rate will make sure the loop runs at 5Hz.
Regarding the script not stopping when pressing Ctrl-C:
KeyboardInterrupt will be handled differently than in normal Python scripts when using rospy.
rospy catches the KeyboardInterrupt signal to set the rospy.is_shutdown() flag to true. This flag is only checked at the end of each loop, therefore if pressing Ctrl-C during the for-loop executions, the script cannot be stopped because the flag is not checked immediately.
A manual way to signal a shutdown of the node is to use rospy.signal_shutdown(). For this, the disable_signals option needs to be set to true when initializing the ROS node (see Section 2.3 here). Note that you will additionally have to manually invoke the correct shutdown routines to ensure a proper cleanup.
I write a Python script to manage my account on a webpage automatically.
Code Description:
The script has a while loop and at the end of the loop, it waits 12 hours before starting again.
Before the while loop starts, it's logging in to my account, and when entering the while loop, it checks if I'm still logged in. If not, it's logging in to my account again.
Problem:
After re-entering the while loop (first time everything goes fine), the script does only work, when print("Name is:") and print(name) is at the very beginning. I tested it several times and maybe it is just a bug/glitch, which was just unlucky to be caused only when the print statements aren't there, but this is very confusing me right now, how those print statements fixed my issue. I would like to know, what is or could causing the issue and how do I have to solve it properly?
Some side info:
The webpage is saving the login credentials through session cookies with a lifetime of ~6 hours. So after re-entering the script loop again, I'm not logged in for sure. If I'm reducing the wait time to 30 minutes instead of 12 hours, the script works also without the print statements.
General notes:
The script is running through nohup on my Raspberry Pi 3
Python version is 3.7.3
Code related notes:
I'm using the post method from requests to log in to my account
For checking, if I'm still logged in, I'm using beautifulSoup4
The following code is abbreviated and in a very basic shape.
"account" is an instance of a self-made class. When instantiating, it is log in itself with arguments, if given
This is the core code:
import time
import requests
from account import Account # costum made class
from bs4 import BeautifulSoup
# login credentials
name = "lol" # I replaced them with placeholders
pw = "lol"
account = Account(name, pw) # instantiating an account class and log in itself with given arguments
while True: # script loop
print("name is:") # Without those both print statements,
print(name) # the code won't work
if not account.stillAlive(): # if not signed in anymore ...
account.login(name, pw) # ... sign in again
account.doStuff() # Do the automating stuff
time.sleep(43200) # Wait 12 hours, before entering the while loop again
This is the doStuff() method from the Account class:
def doStuff(self):
html = requests.get("example.com").text # Note: example.com is only for demonstration purpose only
crawler = BeautifulSoup(html, "lxml")
lol = crawler.find("input", attrs={"name": "Submit2"}).get("value")
# ...
Error message:
So, if I'm executing the program without the print statements, I'm getting this error:
lol = crawler.find("input", attrs={"name": "Submit2"}).get("value")
AttributeError: 'NoneType' object has no attribute 'get'
This does not occur when executing with the print statements. With the print statements, the code runs fine.
My guess
My guess is, what the memory management of Python is deleting the name variable. When entering the script loop in the first time, I'm already logged in and therefore it is skipping the account.login(name, pw) part. Since this is the only part, where name is continued to be, maybe Python is interpreting this as dead code after too many time has passed without the line to be executed, and don't see the reason to keep the name/pw variable and deletes them. Still, I'm just an amateur and I don't have any expertise in this segment.
Side notes:
This is my first question I'm submitting, if I forgot or did something wrong, pls tell me.
I already searched for this problem, but I didn't find anything similar. Maybe I just searched badly, but I searched for a few hours now. If so, I apologize. (I had to wait for every test 12 hours and since I tried it several times, you can tell, I had some time available to search)
I am working on a problem where i should collect data from running program numerous times. For example, every time the program finishes commands, it give certain value t, which is different every time run it. My task is to collect t from N runs of the program. t is going to be different every run. here is the program:
import random
th=0
t=0
tr=0
result=[]
for i in range(7):
i=random.randint(0,1)
result.append(i)
print(result)
a=0
b=len(result)-1
while th<50:
j=random.randint(a,b)
i=j-1
k=j+1
if k<b
k=0
if result[i]==result[k]:
if result[j]!=result[i]:
result[j]==result[i]
th=0
t+=1
else:
th+=1
t+=1
else:
th+=1
t+=1
tr= t-th
print(tr)
print (result)
In this program every run gives you new result. In this generated array there will be obviously every time different arrangement of 0 and 1 and therefore, different t. So resulting t, tr, will be ofcourse different.
I don't know wheter i should do it in new window, or there is a certain function that can do this. Also, if this question is to easy, and there is literature for it, please write what is the name of this kind of problem. thanks :)
btw, im working in python 3.6
See how to make one Python script launch another: you can write a Python script to run the other script and gather the output. You can receive the output as return value from a function call, and tally it just as you would from any function.
Note that your "running program" and your master script need to agree on the form of the information returned: know the data types you're receiving. If you're in doubt, start by having your master script print out what it receives, and the type of each returned value.