Thank you Mike, Now I'm seeing a bigger picture for what you're up against.
Yes, the new Threading model in Witango 5.0, although greatly more efficient in many respects, can introduce timing issue with controlling Transaction "blocks". I haven't seen mentioned what Database you're using? For such a fine need of control, Stored Procedures in SQL Server, for example, can help. A Stored Procedure will execute much faster than a series of Database Actions, which could go a long way to eliminating timing/resource conflicts. Hope this helps. Cheers... > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] > Sent: Thursday, April 22, 2004 3:15 PM > To: [EMAIL PROTECTED] > Subject: RE: Witango-Talk: Sleep & While + explanations > > > Thank you all for your suggestions and comments. > > My confusion is generated by the fact that I do not know how > to control the > DB access anymore. > In Tango 2000, it was (relatively) simple. Using "Begin > Transaction/End > Transaction" I knew that all other processes would not use > the DB while my > writing operation (for ex.), and the thread would not have > been suspended > while doing this. > > In V5.0, if I understand this correctly: > 1- there is no way to guarantee, the thread will not be > interrupted while > processing inside BT/ET; and > 2- there is no way of knowing if the BT/ET has already > started in a another > switched-out thread, unless I design & use some method to synchronize > threads (just like a mutex, for ex.). > > My goal was to associate a variable with the exclusive rights > to the DB. > For ex. if the variable>0 it shows the DB is locked, I can > wait in a loop, > using sleep() for a few ms; > When the variable=0 I can increment it, and then check if > variable=1, lock > the DB for exclusive access, etc. > I do not believe that using the available metatags I can have > such a fine > control over the process to avoid dead locks or race > conditions; but it is > seems better than not trying to control it at all. > (There is probably a good reason why .NET implemented so many > classes to > prevent mishandling of threads.) > > Of course I might be wrong on all accounts. > > > Mike. > > -----Original Message----- > From: Scott Cadillac [mailto:[EMAIL PROTECTED] > Sent: Thursday, April 22, 2004 12:25 > To: [EMAIL PROTECTED] > Subject: RE: Witango-Talk: Sleep & While + explanations > > Hi Mike, > > > I am a little confused by your response, since my question was in > > regard to sleep( milliseconds), which I need in order to > save CPU in a > > loop that checks resource availability. Any browser would wait just > > fine for a couple of hundred milliseconds. > > If this is the case, why put the check into a loop at all? > > If the system needs a tiny bit of time before the resource > can respond, then > just let it run as is. > > I understand "why" you want a sleep() function, but I would consider > carefully it's implications before using it in a Web application. > > > > BTW, I am doing exactly what you suggest, rethinking my > application. > > Until now it worked just fine, under Tango 2000, never had > a problem. > > It still works OK now, under Witango 5 in a test environment, but I > > feel uneasy to move it into the production because I did > not test it > > in a real, multiuser environment. The big problem is I lack > > understanding of how to deal with multi-threading when no > controlling > > mechanism is available for managing threads. > > I guess we must be missing a piece of the puzzle here, as to > specifically > what multi-threading concerns you have. > > If the issue revolves around a particular database query that > has a habit of > taking a long time, then you will be happy to learn that > "threading" under > Witango 5.x Servers are greatly improved. > > Tango2000 used "co-operative" threading, whereas Witango 5.x uses > "pre-emptive" threading. This is an automatic build-in feature of the > Server. > > If resources get scarce, then Witango will respond with > greater speed and > efficiency then Tango2000 ever can. > > The CPU usage spawned by the "waiting" will be reasonably > managed - if it's > not, then this is the point where "I" would rethink what I'm doing. > > But yes, managing your own Threading is a great advantage too > - I also do > NET development. But even with this kind of power, if a > process is going to > routinely take a long time, then it's time to rethink the application > design. > > I recently did a Custom Reporting application. Another > department of my > customer was supplying these huge XML files full of Financial figures > (200mb+), and my Web app was dynamically parsing the XML for > particular > content and displaying them for the web - simple enough work. > > But....the processing was incredibly time/CPU intensive for > each request, > because the files were so huge, that the user was waiting up > to 10 seconds > for responses. > > So, I did a complete rebuild of the project where I built a > Windows Service > application that pre-parsed the XML files into smaller more manageable > chunks. Instead of one big file, I now have 200 tiny ones. > > The project got carried away because the sample XML files I > started with > were less than 1mb - next time I'll think further ahead. > > Hope this helps.... > > > > > Mike Bravu. > > > > -----Original Message----- > > From: Scott Cadillac [mailto:[EMAIL PROTECTED] > > Sent: Thursday, April 22, 2004 11:03 > > To: [EMAIL PROTECTED] > > Subject: RE: Witango-Talk: Sleep & While + explanations > > > > Hi Mike, > > > > With regards to your wishful thinking of a sleep() function in > > Witango, I think you need to rethink your application a bit. > > > > Regardless of the development platform that may, or may > not, support a > > "sleep" or "wait" process - the client component (browser) of your > > "Web" > > application has limited tolerance for such a thing. > > > > Browsers don't like waiting. Although you can craft some > special HTTP > > output to make a browser wait (checkout the "Push" attribute), the > > results are not always User friendly. > > > > I would suggest building a special webpage/window that periodically > > "checks" > > with the Server if the requested resource is free yet. You > can do this > > with JavaScript, or with a META Refresh - and also provide > Users with > > intelligent messages. > > > > I know this is not a simple solution from a developer point > of view, > > because it's more in the interest of the end-user - but who said > > programming would be easy? > > > > ----- > > And although it has been a long time coming, I understand > an <@WHILE> > > Meta tag will be coming in version 5.5 (or 6.0?). > > > > > > Hope this helps. Cheers.... > > > > (Note: new phone number April 26th: 403-254-5002) > > > > Scott Cadillac, > > 403-281-6090 ~ [EMAIL PROTECTED] > > ------------ > > XML-Extranet ~ http://xmlx.ca ~ http://forums.xmlx.ca Well-formed > > Programming in C# .NET, Witango, MSIE and XML > > ------------ > > IExtranet ~ http://iextranet.ca > > Witango ~ http://witango.org > > EasyXSLT ~ http://easyxslt.ca > > IIS Watcher ~ http://iiswatcher.ca > > ------------ > > > > > > > > > > > > ________________________________ > > > > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] > > Sent: Thursday, April 22, 2004 10:25 AM > > To: [EMAIL PROTECTED] > > Subject: RE: Witango-Talk: Sleep & While + explanations > > > > > > > > I need sleep() (on the server side) to wait for > availability on a > > locked resource ( without loading the CPU ). > > If I use an external procedure (dos wait) I am not sure > what is the > > delay needed to load the DOS interpreter; and I would prefer not to > > bind the the solution to an OS. Java can solve all this > (provided it > > is already > > loaded) but I was curious to see if somebody found a simpler way. > > > > I was aware of while action and that would work just > fine; however > > that means I end up fragmenting a results page action; I'd > rather use > > <@FOR> if I can make it act as a while (which can be done in all > > programming languages that I know), but I found no way to > do that with > > witango. > > > > I wonder, since there are <@TIMER> and <@FOR> metatags, why not > > <@SLEEP> and <@WHILE> as well? They are obviously closely > related and > > I assume they cannot be that difficult to implement... > > > > > > Thank you for all your suggestions. > > Mike Bravu. > > > > > > > > > > ________________________________ > > > > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] > > Sent: Thursday, April 22, 2004 03:28 > > To: [EMAIL PROTECTED] > > Subject: Witango-Talk: Sleep & While > > > > > > Hello all, > > > > Can anybody help me out with the Witango equivalents for: > > 1- sleep( milliseconds ); and > > 2- while( true ) { } > > > > The solutions that I found are not acceptable: > > 1- except for using externals, if I try to use > <@TIMER> it seems I > > burn the CPU, which is not what I want; > > 2- <@FOR> </@FOR> does not really work or I do not know how to > setup > > Start/Step/Stop > > > > If the solution is already explained in the documentation I > > apologize, I just could not find it. > > > > > > Thank you, > > Mike Bravu > > > > ______________________________________________________________ > > __________ > > TO UNSUBSCRIBE: Go to > > http://www.witango.com/developer/maillist.taf > > > > > > ______________________________________________________________ > > __________ > > TO UNSUBSCRIBE: Go to > > http://www.witango.com/developer/maillist.taf > > > > > > > > > > ______________________________________________________________ > > __________ > > TO UNSUBSCRIBE: Go to http://www.witango.com/developer/maillist.taf > > > > ______________________________________________________________ > > __________ > > TO UNSUBSCRIBE: Go to http://www.witango.com/developer/maillist.taf > > > > > ______________________________________________________________ > __________ > TO UNSUBSCRIBE: Go to http://www.witango.com/developer/maillist.taf > > ______________________________________________________________ > __________ > TO UNSUBSCRIBE: Go to http://www.witango.com/developer/maillist.taf > ________________________________________________________________________ TO UNSUBSCRIBE: Go to http://www.witango.com/developer/maillist.taf
