can't reproduce right now, but usually for this kind of stuff I'd use a
totally external process.
Beware that "several minutes" standing requests may be killed by your
webserver to free up resources (usually governed by the timeout*
parameters).
If you'd like to have that running inside your webserver process, I'd adopt
a slightly different pattern....
1. page that display and process form
2. upon correct submission, call another function with the recalculateEvent
via ajax
3. open a div somewhere to poll for status progress
So you'd have:
a) a thread that processes the form and then return ASAP rendering your
"template" page
b) a thread that does recalculateEvent, called one-time-only by the a)
rendered page
c) a thread that reports execution and returns ASAP, called several times
by the a) rendered page, filling a component within the "template" page
for b) and c) putting a session.forget() at the top should do no harm.
On Tuesday, January 29, 2013 12:29:03 PM UTC+1, Andriy wrote:
>
> I have a time consuming server side calculation, which is triggered by
> edit-form submitting and can run up to several minutes (its a sports event
> data recalculation if rules are changed). During this time I want to
> receive messages via ajax from server and post them in a div for a progress
> visualization. So far I`v done this using DB table for recording log
> messages:
>
> *db.py:*
> #here I store messages
> db.define_table('log', Field('message', 'string'))
>
> *controller #1:*
> def editForm():
> ...
> if form.process().accepted:
> event=db(db.event.id==request.get_vars.id).select().first()
> recalculateEvent(event)
>
> *myModel.py:*
> #recalculation must be accessible from all controller files, so I put it
> in a Model
> import myModule
>
> recalculateEvent(event):
> db.log.truncate() #clear log
> session._unlock(response) #without this, this function does not
> allow functions in other controllers to run
> db.log.insert(message='Starting Calculation')
> db.commit() #if I do not commit after every
> insert, messages do not appear in DB table
> myModule.calculateSomeMoreData()
> for p in players:
> db.log.insert(message='Calculating player '+p.name)
> db.commit()
> ...more calculations...
> p.update_record()
>
> *controller#2:*
> #ajax calls this function every .5 seconds for messages
> def getProgress():
> m=' '.join([l.message for l in db(db.log).select()])
> return json.dumps(dict(m=m))
>
> *View, javascript:*
> $("#submit_button").click(function(e){
> $('#progress').show();
> GetProgres();
> $("#myForm").submit();
> });
> function GetProgres() {
> $.ajax({
> type: "POST",
> url: '{{=URL('controller#2', 'getProgress')}}',
> dataType: "json",
> success: function(data) {
> $('#progress').html(data.m);
> setTimeout(function() { GetProgres(); }, 500);
> },
> error: function (xhr, ajaxOptions, thrownError){
> alert(xhr.status);
> alert(xhr.statusText);
> alert(thrownError);
> }
> });
> }
>
> I have 2 problems with this:
>
> 1. Every other time web2py throws this error after recalculateEvent(event)
> function completes:
> Traceback (most recent call last):
> File "gluon/main.py", line 576, in wsgibase
> File "gluon/globals.py", line 749, in _try_store_in_cookie_or_file
> File "gluon/globals.py", line 768, in _try_store_in_file
> IOError: [Errno 13] Permission denied
>
> If I remove db.log.insert+db.commit lines - no error. But how else can I
> transfer live data between running real-time function in a model and
> function in a controller? I tried storing messages in a session, but it
> does not update until model function is finished.
>
> 2. Ajax call from view works only when hosting on my local machine and
> only in Opera and IE. It does not call controller#2/getProgress function in
> Chrome and Firefox on localhost. When hosting on outside server it does not
> work on any browser... Only Firefox triggers ajax error, with
> xhr.statusText='error'.
>
> I guess this is something to do with that I`m triggering form submission,
> calculation function and at the same time polling sever. But I have no idea
> what to do.
>
> May be if my approach is totally wrong somebody can suggest how to
> implement this in other way.
>
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