Some connection pools will reduce back down to a minimum size, others will retain the
number of connections that have been opened. Also, remember that most of the SQL you
are
executing will be fast-running -- so once the servlet is done processing and releases
its connection, that connection is immediately available to another function. So if
you
don't want 300 connections, and you are actually expecting 300 simultaneous hits, you
can reduce the number of maximum open connections -- keeping in mind that there will be
at least some lag before a user gets a response, because you have to wait for a
connection to free up. You'd run into the same problem if you weren't using a
connection
pool and 300 people hit simultaneously anyway.
What you described in your last paragraph is a Connection Pool. And they communicate
very fast.
Alvin Lau wrote:
> ok, say i'm going to use a pool to hold my connections. initially the pool
> has only five connections. I assume that there are 50 students in a class.
> So they propably login at the same time. They are not all hit the
> button at the same second. say, 30 of them hit the button at the same
> second, then my pool for login will now holding 30 connections (I think
> connection's pool will automaticaly increase its size when it's
> nessecary). Am i correct? Also does a connection's pool will automatically
> reduce its size after some of the connection returned? Accounding to you,
> I need a connection's pool for all my servlets that access db. Say, my
> project has 10 servlet that will access db. So, in total, I have 300
> connections if the pool doesn't reduce its size automatically. I think 300
> connections are really too much. Do you have any solution for me.
>
> One of the solutions(I think) is that: i write a servlet that used to hold
> all the connections in my project. when other servlets want to get a
> connection, they just get it from my connection's servlet. Is it possible?
> How fast do the servlet commumicate with each others?
>
> alvin
>
> On Thu, 25 Mar 1999, Scott Neufeld wrote:
>
> > You answered your own question -- multiple simultaneous queries requires multiple
> > simultaneous connections. So, you can create a new connection each time, or use a
> > connection pool. The first is inefficient because it is expensive to open and
> > close/kill connections to a database. The second is efficient because it maintains
> > open connections to the database.
> >
> > Go to www.javaexchange.com for more info on this.
> >
> > Boy, it's Connection Pool day here on the servlet-interest listserv!
> >
> >
> > Alvin Lau wrote:
> >
> > > Thank you for your information about transaction.
> > >
> > > I used only one connection (put it in init()and use it in doPost()). I
> > > didn't test my code seriously ( it seem to be working well). It's not easy
> > > to debug. What do you mean by "multiple simultaneous connection"? also a
> > > question want to ask you, can a connection handle mutiple simultaneous
> > > query correctly? What will go wrong if I do it in my way?
> > >
> > > I'm not with my computer these two day. I think i will send my codes here,
> > > and may be you (or someone) can give me some +ve advice.
> > >
> > > alvin, lau
> > >
> > > On Thu, 25 Mar 1999, Scott Neufeld wrote:
> > >
> > > > Do you create a new connection each time a user tries to login? Or do you use
> > > > the same one each time? The first is extremely inefficient, and the second one
> > > > will not allow multiple simultaneous connections, and this is also extremely
> > > > inefficient.
> > > >
> > > > It is not just for transactions, it is for maintaining open database
> > > > connections that can be used as needed by one or more servlets (or helper
> > > > classes).
> > > >
> > > > Alvin Lau wrote:
> > > >
> > > > > I'm building a marketing's games, and I made a login's servlet a few weeks
> > > > > ago. What I did is that, when a user login in, first I check the user pw
> > > > > and id, and if I find a record in my db, then I create a new user's obj
> > > > > and put it in the session.
> > > > >
> > > > > I really don't understand why you need a connection pool. For me you need
> > > > > a connection pool only if you have to do transaction. Am i correct?
> > > > >
> > > > > If you want to see my codes, just let me know.. :-)
> > > > >
> > > > > alvin lau
> > > > >
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