Hi Folks,
Soak Test - Running a system at high load for a prolonged 
period of time. For example, running several times more 
transactions in an entire day (or night) than would be 
expected in a busy day, to identify and performance 
problems that appear after a large number of transactions 
have been executed. 

Objectives of Soak Testing

The objective of soak testing is to identify any 
performance problems that may appear after a system has 
been running at a high activity level for an extended 
period of time.

It is possible that a system may? Stop? Working after a 
certain number of transactions have been processed due to 
(for example): 
1.	Serious memory leaks that would eventually result 
in a memory crisis; 
2.	Failure to close connections between tiers of a 
multi-tiered system which could halt some or all modules of 
a system; 
3.	Failure to close database cursors under some 
conditions which could eventually result in the entire 
systems stalling; 
4.	Gradual degradation in response time of some 
function as internal data structures become less efficient 
during a long, high intensity test. 
Soak testing provides an opportunity to identify such 
defects.

I think it will help you out 

Regards,
Shankar

To identify memory leak problems for longer period

simply Soak esting is a combitation of load & endurance
testing. thr this we can identify the memory leaks of an
application.

ideyifying the memory leaks in application.