MaxActive?? how many connections should be made available

Question

Can anyone recommend what I should set the maxActive="" property of my database resource connection for a medium to large scale ecommerce application.
How many simultaneous database connections might I expect?
I know this is dependant on the volume of traffic on the site, but I just need a general Idea, I currently have maxActive="100", but I'm a little worried that this may be insufficent for a site that may have up to 5000 concurrent users.
Thanks in advance.

Answer 1

Do you have a formula for the above, to give an
estimated requirement for maxActive connection
settings?
Sorry! there is no real formula but since you are working on a web application the number of connections used will be close to the number of requests at a time on your web application.
And the number of concurrent users dosent give much idear about the number of concurrent requests becouse users dont keep clicking all the time. Most of the time they will be reading somthing on the browser.
Here is a simple calculation but only accurate if you assume that server takes 1sec to process each request.
If the number of concurrent users is 5000 and each user makes a click once in every 60secs, then there will be aproximatly 5000/60 requests/sec. That is 83.333... requests
I assume the only warning sign I will get when
maxActive is reached will be browsers 'hanging' until
it either times out or a connection is released to
the pool?Browsers normally times out and display an error if the server do not respond within a predefined interval (Normaly 90secs) thats what you should watch out for.
By the way if what you want is to make sure the maximum is never reached just set it to a negative value.(Assuming that you are using apache commons pool. negative means infinity)
And set reasonable numbers to MaxIdle, MinEvictableIdleTimeMillis, and TimeBetweenEvictionRunsMillis. Please read the documentation of the setter methods of above attributes if you dont know what above attributes are for.
you can also add a back end page to your web application to display the staticstics of the pool.
such as the number of current idle connections, current active connection and ect...