Hi Sanjay,
you can avoid the problem by using the double-checked locking pattern
(Schmidt-Harris) as follows:
public static ConnectionPoolAsSingelton getInstance() {
// check for null singleton
if(instance==null)
{
// obtain lock
synchronized( this )
{
// check for null again in case initialization
// already occurred in another thread
if(instance==null)
{
return new ConnectionPoolAsSingelton();
}
}
}
else
return instance;
}
the synchronization overhead is limited by the first null check,
so that further calls to the method never reach the synchronization code
and its associated overhead.
Regards,
Jin
-----Original Message-----
From: Radhakrishnan, Sanjay (c)
[mailto:[EMAIL PROTECTED]]
Sent: Thursday, April 13, 2000 10:08 AM
To: [EMAIL PROTECTED]
Subject: Re: Connection Pool
Hi Thomas,
I have 2 questions,
1. the protected instance in the Singleton class should be static
right? and Im sure thats what you meant.
2. Also shouldn't you make both the get and put methods thread safe.
You've mentioned that only the Put method should be thread safe. Can i
Synchronize on the static instance to make the methods threadsafe
Thanks for your time
Sanjay
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]
Sent: Tuesday, April 04, 2000 10:53 AM
To: [EMAIL PROTECTED]
Subject: SV: Connection Pool
Hi Sanjay
The best way is to implemets a Singelton (see the GoF book) that uses a
ConnectionPool.
public class ConnectionPoolAsSingelton {
protected ConnectionPoolAsSingelton instance; // Store the
Singelton here
private ConnectionPoolAsSingelton(...) { // yes private
constructor
....
}
public static ConnectionPoolAsSingelton getInstance() {
if(instance==null)
return new ConnectionPoolAsSingelton();
else
return instance;
}
//Put methods for your connpool here but keep in mind that this
code should bee thread safe.
}
to get an instance of connectionpool just call the static function
ConnectionPoolAsSingelton pool =
ConnectionPoolAsSingelton.getInstance();
This should work fine but if you have any problems pleas email me att
[EMAIL PROTECTED]
/Thomas
-----Ursprungligt meddelande-----
Fran: [EMAIL PROTECTED]
[SMTP:[EMAIL PROTECTED]]
Skickat: den 4 april 2000 15:57
Till: [EMAIL PROTECTED]
Amne: Connection Pool
I am trying to set up a connection pool for my JSP Project. Now I
know that
there are few ways to implement a connectionpool. My first thought
was to
put in the the servlets init method,But then what do i do for my
other
servlets/JSPs, do i create a connectionpool for every servlet?.
Is there a standard technique for implementing connection pools. I
think
the best solution would be to have it in a common place which all the
JSPs
and servlets can access, something like a global.asa file in ASP.
I would like to hear your thoughts on this.
Thanks for your time
Sanjay
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