Since AchipA is working on other changes to cron.py and cron.py is his, I think I should wait to see if AchipA includes additons with Massimo's preferred format below before being so bold as to submit a patch myself.
John Heenan On Feb 9, 10:54 am, mdipierro <mdipie...@cs.depaul.edu> wrote: > I have no objection to adding this feature. I do not like the !*" > prefix. > > I think we can do: > > @hourly root file -> exec file in Popen > @hourly root file.py -> exec file in Popen with python > @hourly root *file.py -> exec file in Popen with python -S <app> -M -R > <file> > @hourly root **file.py -> exec file in Popen with python -S <app> -R > <file> > @hourly root *file -> exec file in Popen with python -S <file> -M > @hourly root **file -> exec file in Popen with python -S <file> > @hourly root *"data" -> exec "data" without Popen with environment as - > M > @hourly root **"data" -> exec "data" without Popen without environment > as -M > @hourly root *"filename" -> execfile filename without Popen with > environment as -M > @hourly root **"filename" -> execfile filename without Popen without > environment as -M > (we can distinguish data from filename checking if "..." starts with > './' or '/'.) > > I would take a patch in this direction. You only add the last 4 > options at the end of the cron file. There is nothing else that needs > to be done I think. > > Massimo > > All is needed it a > > On Feb 8, 6:30 pm, John Heenan <johnmhee...@gmail.com> wrote: > > > Hi > > > I stated "My point is can we have an option to:" > > > Maybe I should code up a patch for cron.py and submit it for > > examination. Cron.py is impressive, I am not criticising it or > > attacking its approach. > > > The option I am requesting are ADDITIONS to cron.py that are TRIVIAL > > to code in as additions to cron.py. Web2py already has a prepared > > environment ready to be passed for exec use. > > > To reiterate, the option I am requesting is an additional option (not > > a replacement) to do an exec (or execfile) on a file that ends > > with .py (or .pyc) AND an option to do an exec on a string (such as > > "import a; a.mycronaction()") > > > For example, suppose ! is chosen to indicate not to use the default of > > the Popen class wrapper but to use exec instead, then the following is > > an example of use: > > > */10 * * * * root ! > > **expire_sessions.py #use the web2py environment with execfile on > > the .py file but do not execute models > > or > > */10 * * * * root !*"import a; > > a.mycronaction()" #use the web2py environment with exec on the string > > and include execution of models > > > I do not want to become involved in a grand philosophical or > > ideological debate about the merits or otherwise of using the Popen > > wrapper class verses the internal Python exec (or execfile) function. > > For trivial tasks (such as deleting stale session files) the Popen > > class wrapper is overkill. Using Popen involves unnecessary extra RAM > > use and process invocation. Invoking a Python process is very > > expensive in CPU and RAM terms. In fact Python is impractical in a web > > environment unless the Python process remains persistent, This is the > > reason why hosting is relatively expensive for python web solutions > > compared to PHP and Perl. > > > While such concerns might seem trivial for tasks that are not repeated > > often, it is not trivial if hosting is in an environment where there > > are penalties for exceeding allocated RAM, such as I believe occurs at > > Webfaction, popular with those trialling web2py. > > > For trivial housekeeping tasks, just a minimal (non models) > > environment associated with the application is adequate, such as is > > currently passed in for use with Popen. > > > If tasks are so involved that processes are at a non negligible risk > > of choking then users will hardly be concerned about using execfile > > instead of Popen and will instead code up an independent supervisory > > process outside web2py. > > > Deadlock or race conditions are not any more of an issue using exec > > than with normal code (provided the code passed in for exec does > > nothing out of the ordinary). A new thread is not invoked. > > > As is, cron.py waits for a Popen invoked process to end without a > > supervisor which can result in a lock up of web2py. > > > It can be argued that there is a lack of hard quantified information > > about the resources used by Python based web frameworks. Those who > > develop websites and GUIs have frequently little care about boring > > issues of resource usage. I bothered to take a look and was horrified > > by the memory usage of Python. We need to show respect for practical > > issues associated with using Python. Otherwise web2py and other > > frameworks risk becoming relegated to academic toys that are from > > 'enterprise' class. Java based frameworks are fighting back. Sun is > > pushing GlassFish heavily into the enterprise environment. > > > Python based frameworks cannot expect to be competitive with PHP at > > what PHP is best at (low resource usage) if Python frameworks don't > > address issues in a practical way that are holding back their adoption > > (such as resource usage leading to expensive hosting). > > > John Heenan > > > On Feb 8, 11:40 pm, AchipA <attila.cs...@gmail.com> wrote: > > > > Fiddling with this now, but have a few concerns, so I'd like Massimo > > > to chime is as the exec expert. The main reason for going POpen is to > > > have a clean, thread safe environment, and with exec I'm not sure we > > > won't hit race conditions or deadlock possibilities, especially if we > > > touch on models. Some help how to exec stuff with the proper > > > environment would be welcome :) > > > > Another thing to note is that when execing, we no longer have control > > > over what we execute - i.e. while we can kill/clean zombie POpened > > > processes, if we get stuck in just another thread (=with exec) it's > > > stuck there until the whole web2py/webserver is restarted. > > > > On Jan 31, 7:27 am, John Heenan <johnmhee...@gmail.com> wrote: > > > > > I have not get my point across. > > > > > By 'Python exec' I mean using the 'exec' internal Python command. I > > > > don't mean 'Python exec' as a shorthand for 'execute a new Unix, > > > > Windows or Mac OS process under the ownership of the cron code written > > > > in Python'. > > > > > I have just examined the most recent trunk version of cron.py > > > > inhttp://code.google.com/p/web2py/source/browse/gluon/contrib/cron.py > > > > > For .py files the Popen command is still executed using the > > > > cronlauncher class that uses Popen > > > > > For those of us trying ot keep RAM usage down, who don't want to use a > > > > regular crontab and who only want to run Python files, using Popen is > > > > not necessasry. > > > > > My point is can we have an option to: > > > > > 1) Just do an Python exec on an opened file contents (with ot without > > > > the models envrionment), instead of doing a Popen > > > > 2) Have an option to do an Python exec on a string, such as on "import > > > > a; a.mycronaction()" > > > > > Thanks > > > > > John Heenan > > > > > On Jan 31, 2:17 pm, mdipierro <mdipie...@cs.depaul.edu> wrote: > > > > > > Unless we misunderstand we have that already. The file just needs to > > > > > end in .py as in > > > > > > * * * * * root myscript.py > > > > > > You can also call actions > > > > > > * * * * * root *myscript.py > > > > > > so that models are imported. > > > > > > On Jan 30, 8:36 pm, John Heenan <johnmhee...@gmail.com> wrote: > > > > > > > Hi AchipA > > > > > > > Another feature request, if the cron file is a python file, how > > > > > > about > > > > > > a cron option to open the file and do an exec on the file contents? > > > > > > > Thanks > > > > > > > John Heenan > > > > > > > On Jan 31, 12:33 pm, John Heenan <johnmhee...@gmail.com> wrote: > > > > > > > > Hi AchipA > > > > > > > > Your cron is nice work and neatly deals with the messy side of > > > > > > > launching an independent OS process and waiting for it to finish. > > > > > > > > For those of us who do not wish to launch an independent process > > > > > > > (to > > > > > > > keep down memory use) and are happy to stick with Python for cron > > > > > > > jobs, following is a request to add in the following feature to > > > > > > > your > > > > > > > cron fpr web2py. > > > > > > > > Provide a mechanism to just perform a Python exec on a string > > > > > > > statment. > > > > > > > > For example a string statement might be > > > > > > > "import a; a.mycronaction()" > > > > > > > > Thanks > > > > > > > > John Heenan > > > > > > > > On Jan 31, 6:52 am, AchipA <attila.cs...@gmail.com> wrote: > > > > > > > > > Just to chime in, I'm still alive and preparing an update to > > > > > > > > cron as > > > > > > > > quite a few things changed since I last touched it. As for the > > > > > > > > questions - all cron modes support the * and ** syntax, and > > > > > > > > yes, cron > > > > > > > > files can be modified on the fly. > > > > > > > > > On Jan 26, 4:00 pm, mdipierro <mdipie...@cs.depaul.edu> wrote: > > > > > > > > > > I did not write cron personally and I am still trying to > > > > > > > > > understand > > > > > > > > > some of it, Attila did. > > > > > > > > > I am in the looking at cron these days to treamline it a bit > > > > > > > > > and I am > > > > > > > > > trying to understand better as it works. > > > > > > > > > > Since windows does not have cron, you should use web2py > > > > > > > > > hardcron. It > > > > > > > > > should work on windows 7 but I have not tried it. The "root" > > > > > > > > > is the > > > > > > > > > username that should run the cron task. It is only used by > > > > > > > > > extcron and > > > > > > > > > ignored otherwise (but must be there, for compatibility of > > > > > > > > > syntax). > > > > > > > > > > I am not sure if tasks staring with * or ** run under extcron > > > > > > > > > so I > > > > > > > > > suggest not using pycron. Given hardcron you do not need > > > > > > > > > pycron > > > > > > > > > anyway. > > > > > > > > > > Mind that this is in the process of being refactored a bit. > > > > > > > > > Perhaps > > > > > > > > > you can help with testing and debugging so you can be sure it > > > > > > > > > works as > > > > > > > > > you need it. > > > > > > > > > > On Jan 26, 4:27 am, Oguz Yarimtepe <oguzyarimt...@gmail.com> > > > > > > > > > wrote: > > > > > > > > > > > Hi, > > > > > > > > > > > I was trying to use the cron property of web2py at my > > > > > > > > > > project. I am > > > > > > > > > > using web2py under windows 7. I had installed wamp server > > > > > > > > > > with mod_wsgi. > > > > > > > > > > According to the documentation it is suggested to use the > > > > > > > > > > external cron. > > > > > > > > > > I tried to test the soft > > ... > > read more » -- You received this message because you are subscribed to the Google Groups "web2py-users" group. To post to this group, send email to web...@googlegroups.com. To unsubscribe from this group, send email to web2py+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/web2py?hl=en.
