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How to find out Memory Leak in an application?

There are many reasons for memory leak and being a tester its tough to find exact reason. The basic thing we need to understand what is memory leak? How it occurs?
Memory leak can be defined as the un-allocated space in a system which was used by a program and after  use it was never returned to the operating system. This un-allocated (unused memory) can cause shortage of memory and may crash the entire system.

 There are few steps which may help to find out memory leak in  a system:
  1. We can monitor the memory graph by using perfmon and check if the memory utilization is keep on increasing and remain at peak even without any load, it shows the memory that was used while executing the program is still in use even the program doesn't needs it. The un-managed code is not efficient enough to release the memory and free it after use, which may cause out of memory issue.
  2. You can check the throughput graph while load testing and if there is sudden spike in it then it can be one of the reason for memory leak. But we can't assure the spike in graph is because of memory leak, the other reason could be due to network traffic, data base connectivity issue etc.
  3. We have GC to collect all the un-allocated space and return it to system, it has some limitations:
  • In a manually managed memory environment: Memory is dynamically allocated and referenced by a pointer. The pointer is erased before the memory is freed. After the pointer is erased, the memory can no longer be accessed and therefore cannot be freed.
  • In a dynamically managed memory environment: Memory is disposed of but never collected, because a reference to the object is still active. Because a reference to the object is still active, the garbage collector never collects that memory. This can occur with a reference that is set by the system or the program.
  • In a dynamically managed memory environment: The garbage collector can collect and free the memory but never returns it to the operating system. This occurs when the garbage collector cannot move the objects that are still in use to one portion of the memory and free the rest.
  • In any memory environment: Poor memory management can result when many large objects are declared and never permitted to leave scope. As a result, memory is used and never freed.

Comments

  1. UnknownNovember 29, 2013 at 7:25 AM

    grate efforts keep it I rally like this posts

    Regards,
    kiran

    ReplyDelete
    Replies
    1. Ravi RanjanDecember 9, 2013 at 11:46 AM

      Thanks Kiran... I will continue to strive more and more..

      Delete

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