Ok I've made the perfect system that start a new worker when it's
necessary. My problem is that web2py don't run the tasks and I don't know
why (so my system is not so perfect!!).
I've add this task in the scheduler. It only save a file "alert_file.txt":
def save_alert_file():
file = open('%s/static/alert_file.txt' %request.folder, 'w')
file.write('')
file.close()
I run it every 300 second (5 minutes).
Webfaction servers use Centos 7.
I've made a bash script called hyd.sh that start the worker of my app
called "hydrover_oleodinamica" if the file datetime is older than the
current datetime minus 7 minutes:
file=
"$HOME/webapps/w2p_2_12_3/web2py/applications/hydrover_oleodinamica/static/alert_file.txt"
file_datetime_s=$(date -r $file +%s)
alert_datetime_s=$(date --date '- 7 minutes' +%s)
if [ $alert_datetime_s -gt $file_datetime_s ];
then
nohup /usr/local/bin/python2.7 ~/webapps/w2p_2_12_3/web2py/web2py.py -K
hydrover_oleodinamica & 2>&1 > $HOME/hyd.log &
fi
It works fine.
I've add it in the server crontab that run it every 10 minutes:
*/10 * * * * $HOME/hyd.sh
If I cancel all workers in the db and all related processes in the server,
this system works like a sharm.
A worker is started, all tasks are running.
After 10 minutes no other worker is started, perfect.
If the Webfaction server get restarted, all the processes are killed
include the workers.
In this case the worker is started, it's in the db but tasks don't run.
And so the crontab start a new worker every 10 minutes.
Someones knows why?
As I can't restart the Webfaction server by myself it's difficult to make
test but I think that when a worker is started by my script after a server
restart, the flag "Is ticker" is false in the worker db record.
What does it mean?
Thanks, regards.
Il giorno giovedì 17 novembre 2016 23:35:31 UTC+1, Niphlod ha scritto:
>
> I'll say it once again: you need a scheduler to run out-of-band pieces of
> things (tasks) that ARE NOT embedded in the web-serving process(es).
> At that point you may as well process out-of-band tasks with a simple ajax
> call, and save yourself setting up the scheduler at all.
>
> It's strongly discouraged to start ANY process inside the webserver
> (stderr/stdout clumsiness with wsgi, enforced timeout on the webserver,
> DDoS attacks, etc). Starting a python process inside a controller (even if
> it's the scheduler) has the same exact cons.
>
> The scheduler NEEDS (read: there is absolutely no valid reason not to) to
> be started as an external and independant process from the webserver: if
> you need it to be started when the server comes up, you NEED to use your
> system's "service" architecture (init.d, systemd, supervisord, windows
> service, etc) .
> Or, if you're using uwsgi, you can use its facility to spawn external
> processes (it's in the default installation script).
>
>
>
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