[Reprinted] Memory leakage

Memory leakage typeHttp://www.red-gate.com/supportcenter/Content/ANTS_Memory_Profiler/help/7.2/amp_memory_leaks)

Most memory problems come down to one of the following types. Determining the type of the problem will help you locate and solve the problem.

Managed Memory leakage

The typical symptom of a memory leak is that the performance degrades while the program runs; performance recovers on restart and then degrades again. The amount of bytes in the. NET heap increases.

Unmanaged memory leakage

The performance degrades while the program runs; this recovers on restart and then degrades again. the number of private bytes (the amount of real and paged memory requested by the Program) in use often increases at a greater rate than the number of bytes in. net heap.

Fragments of a large object Stack

The main symptom of fragmentation is thatOutofmemoryExceptions are thrown even though there is sufficient space on the. NET heap.

Large-capacity RAM usage

Some programs need to use a lot of memory. there is little specific advice that can be given about this, since the best approach to handle the amount of memory used will depend on your program's requirements. using a profiler may give you suggestions for where to optimize code by showing which parts of your program are using the most memory.

 

Memory counters:

By default, ants memory profiler uses the private bytes counter, because this measure is considered the most useful for most kinds of memory problem. 

Windows Task Manager shows the private working set counter by default. The private working set is unavailable in ants memory profiler because it is only accurate immediately after a garbage collection.

The following table summarizes some of the main different ways of measuring memory:

 

counter	description	including shared processes? (DLLs in memory ,. net runtime)	including memory paged to disk?
Private bytes	Includes memory allocated (even if not in use)	No	Yes
Working Set	Only supported des memory in use	Yes	No
Virtual bytes	Only supported des memory in use	Yes	Yes
Private Working Set (Unavailable in ants memory Profiler)	Only supported des memory in use	No	No

Performance Monitor ( perfmon.exe ) has a performance counter called # bytes in all heaps , which is part of. net CLR memory object.

The value of the Performance Monitor # Bytes in all heaps Counter is often larger than the ants memory profiler # Bytes in all heaps Counter. The discrepancy is caused because the Performance Monitor # Bytes in all heaps Counter memory des memory allocated to the. NET heaps but which is not being used, whilst the ants memory profiler # Bytes in all heaps Only supported des memory that is both allocated and in use.