Crontab 产生多个任务实例而不是单个实例

Question

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I have a python script which needs to run every 5 minutes. I am calling this script via a bash file named activate.sh :

#!/bin/bash
../../env/bin/python3 ./run.py

Then to run this task every 5 minutes, I have a crontab job configured as such:

*/5 * * * * cd /var/www/usa/api/BackgroundTasks && /bin/bash ./activate.sh

I have literally the same setup running on 3 different servers 2 of which work just fine and activate the task only once. The one on the USA server however spawns multiple instances of run.py . This went so far that it nearly filled up the entire memory causing performance issues.

Here is the app.py code but I don't think the issue is there, I think the issue is with cron itself:

import time, sys, os, datetime
try:
    sys.path.append("../")

    from Flabstraction.Flabstraction import Pysqlalchemy, MailingService
    from Flabstraction.constants import constants_dict

    from AutomatedReports import schedules_builder_2
    from DeleteOldJobs import delete_old_jobs
    from StallTimers import stop_timers

    constants_selector = "LOCAL"
    path_to_self = os.getcwd()
    selectors = ['/au/','/eu/','/nz/','/usa/','/demo/']
    for sel in selectors:
        if sel in path_to_self:
            constants_selector = sel.upper().replace('/', '')
            break
    constants = constants_dict[constants_selector]

    mail = MailingService()
    sql = Pysqlalchemy('mysql+pymysql', constants["mysql_user"], constants["mysql_pw"], constants["server_ip"], constants["mysql_db"])

    file = open('./background.log', 'w')
    file.write(str(datetime.datetime.now()) + " : running started. \n")

    if constants_selector in ["LOCAL", "US"]:
        schedules_builder_2(sql, constants["timezone"], constants_selector, mail, constants)    
    if constants_selector in ["AU", "NZ", "EU"]:
        delete_old_jobs(sql, constants["timezone"])

    stop_timers(sql, constants["timezone"], constants["_instance_id"])

    file.write(str(datetime.datetime.now()) + " : running stapped. \n")
    file.close()

    except Exception as e:
        file = open("./background.log", "w")
        file.write("Error occured: ", e)
        file.close()
        raise e

Any idea how to resolve this and why it would be happening on only 1 of 3 servers?

Answer 1

Okay so I went through my code in detail and found that one of my constructors was giving a warning message which essentially froze the script while waiting for an input by the user.

The way I resolved this was by using the getcwd() function imported from os in order to check which folder is calling the python script where this happened.

Having:

├── BackgroundTasks
│   ├── AutomatedReports.py
│   ├── DeleteOldJobs.py
│   ├── StallProjects.py
│   ├── StallTimers.py
│   ├── activate.sh
│   ├── background.log
│   └── run.py
├── Config
│   ├── Config.py
│   ├── common.py
│   ├── connect.py
│   ├── constants.py
├── app.py

I was executing run.py from my activate.sh file. When I run the application I call the app.py .

Using the getcwd() function, I was able to check if I call the script from BackgroundTasks and therefore add a case in my connect.py script to ignore the user input when invoked from that folder.