I didn't think we were talking on the app level. mdipierro wrote: > I am skeptical about initialization code being initialized by the app > because it may take time and web server may kill it. > > My approach is to create an initialization script in private and run > it with > > web2py -S app -M -R private/script.py > > On Jan 27, 10:24 am, Timothy Farrell <tfarr...@swgen.com> wrote: > >> Yes, but WSGI/FCGI web-servers always have several new processes ready >> for requests rather than having to wait for a process to start as soon >> as a request is received. >> >> Be careful about the multiple processes thing. Separate processes can >> import the same module and not be sharing data or code because they are >> run under two separate interpreters in two separate processes. You only >> have to worry about this type of sharing with shared resources like files. >> >> It seems that you're suggesting one interpreter process should parse the >> available plugins and provide that data to other interpreter process. >> Now this could work with threads, but inter-process communication is >> much more complicated and may take longer than it would for each process >> to just parse it's own set of plugins. >> >> -tim >> >> >> >> achipa wrote: >> >>> One itsy-bitsy note about the persistence of WSGI/FCGI/standalone - >>> out of these, only the standalone has serious persistence. WSGI and >>> FCGI can (and will) get restarted on the web server's whim (some >>> webservers come with a predefined number of requests after which they >>> restart the process, just in case). Also, with WSGI and FCGI you can >>> have several parallel processes, which again complicates things (do >>> you consider a second process starting a first load or can it re-use >>> the results of the first one's startup ? It really depends on the >>> usage scenario). >>> >>> As for main.wsgibase(), my bad, I wanted to say 'when' not 'where'. >>> >>> On Jan 27, 4:35 pm, Timothy Farrell <tfarr...@swgen.com> wrote: >>> >>>> I think you're confusing things.... see below >>>> >>>> achipa wrote: >>>> >>>>> The problem is that first start is a very relative term depending on >>>>> how you run web2py, it's not the same for standalone/cherrypy, CGI, >>>>> MOD_WSGI, parallel versions of these, etc. >>>>> >>>> Correct...sorta. We really have three categories here, threaded >>>> persistent python interpreter, persistent distinct processes and >>>> (non-persistent) distinct processes. The third scenario is vanilla >>>> CGI. The core of web2py is started for every request with plain CGI. >>>> However WSGI, FCGI and the standalone setups use some variation of the >>>> other two setups in which case imported modules are not rerun. (Google >>>> agrees...http://code.google.com/appengine/docs/python/runtime.html#App_Caching)> >>>> This means that your >>>> >>>>> startup code could be executed in a whole lot of places, not always >>>>> where you want it. You also have to make arrangements for race >>>>> conditions (what if a web request comes in while you are executing >>>>> your startup function?) >>>>> >>>> This part is only true if your code is in the page processing path (i.e. >>>> main.wsgibase() ). If your code is in an imported module it will only >>>> be run once per executed process.> As an idea, you might want to check/set >>>> a flag variable in cache.ram. >>>> >>>>> If you don't see that flag, presume it's a first start, if it is >>>>> there, consider yourself loaded. This also can lead to a few gotcha's >>>>> (use mutexes to prevent race conditions) and doesn't work with CGI, >>>>> but until somebody suggests something better, it might be worth a try. >>>>> >>>> This is a good point. If you're module has module static variables then >>>> those variables could be accessed from multiple threads and hence would >>>> need to be protected with a lock-type. To see an example of this, the >>>> cache module has "meta_storage" that holds cached information and is >>>> thread-safe. >>>> >>>> -tim >>>> >>>>> On Jan 27, 5:44 am, billf <billferr...@blueyonder.co.uk> wrote: >>>>> >>>>>> Basically, is there any code that receives control when an application >>>>>> first starts that allows some initialisation/configuration that >>>>>> doesn't have to run after every request? >>>>>> >>>>>> I believe code could be put in db.py but that is not ideal >>>>>> conceptually - and would run on every request? >>>>>> >>>>>> I can see that there are pros and cons to the idea of "on start" code >>>>>> and would be interested in peoples' views. >>>>>> >>>> -- >>>> Timothy Farrell <tfarr...@swgen.com> >>>> Computer Guy >>>> Statewide General Insurance Agency (www.swgen.com) >>>> >> -- >> Timothy Farrell <tfarr...@swgen.com> >> Computer Guy >> Statewide General Insurance Agency (www.swgen.com) >> > > >
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