I run for Dump File in WinDbg command
!address -summary
I results are something like this
Usage Summary RgnCount Total Size %ofBusy %ofTota
Free 3739 7ff5`dbbae000 ( 127.960 Tb) 99.97%
<unknown> 1677 5`680a1000 ( 21.626 Gb) 53.31% 0.02%
Heap 20349 4`0049f000 ( 16.005 Gb) 39.45% 0.01%
Stack 230 0`a3e90000 ( 2.561 Gb) 6.31% 0.00%
How can I find what in in Heap? What are objects or what are types?
Is Managed Heap, and Heap is managed heap?
It is very hard to ask Questions Like this, so I added more info
Here is my C# Sample Code
class Program
{
public static int[] arr;
public static AllocateUnmanagedMemory cls;
static void Main(string[] args)
{
const int GBSize = 1 * 1024 * 1024 * 1024/ sizeof(int);
Console.WriteLine("Allocating");
arr = new int[GBSize];
cls = new AllocateUnmanagedMemory();
cls.UnmanagedAllocation();
Console.ReadLine();
}
}
Here is Unmanaged Allocation Code:
using System;
using System.Runtime.InteropServices;
public class AllocateUnmanagedMemory
{
static IntPtr pointer;
public void UnmanagedAllocation()
{
pointer = Marshal.AllocHGlobal(1024 * 1024 * 1024 );
}
}
And results from WinDbg Preview in Windows 10
-- Usage Summary RgnCount ----------- Total Size -------- %ofBusy %ofTotal
Free 59 762f7000 ( 1.847 GB) 46.17%
<unknown> 98 4493e000 ( 1.072 GB) 49.76% 26.79%
Heap 15 40158000 ( 1.001 GB) 46.50% 25.03%
Image 174 2db2000 ( 45.695 MB) 2.07% 1.12%
MappedFile 15 1c51000 ( 28.316 MB) 1.28% 0.69%
Stack 24 800000 ( 8.000 MB) 0.36% 0.20%
I should be able find somewhat that code for Unmanaged Allocation, allocated 1Gb memory.
The command !address operates on a very low level, barely above the operating system. However, it will recognize a little bit of the memory manager that comes with Windows: the Windows Heap Manager.
So, what you see as Heap that is memory which was allocated through the Windows Heap manager. On your level of understanding, that's the native heap.
Any other heap managers will implement their own memory management. Basically they all work similar: they get large blocks of memory from VirtualAlloc() and then try to do a better magement of the small blocks within that large block. Since WinDbg doesn't know any of these memory managers, that memory is declared as <unknown>. It includes, but is not limited to the managed heap of .NET. For other potential uses, see this answer.
Free is memory that can potentially be claimed from the operating system. This may include swap space, not only physical RAM.
Stack, well that's obvious I think.
How can I find what in in Heap? What are objects or what are types?
The answer to this question heavily depends on which heap you're talking about.
The Windows Heap Manager ("native heap") just manages memory and does not manage types. It's not possible on that level to distinguish two objects of the same size but different type. If you have a memory leak, you can only give a statement like "I have a leak of n bytes". To find our more about the native heap, start with !heap -s and look up the other !heap commands.
The .NET managed heap retains a type system. To analyze the managed heap, you need an extension for WinDbg called sos. Usually you load it by .loadby sos clr. It has a command !dumpheap -stat which may give you a first impression of its capabilities. (Run the command twice if you get an error message)
This should give you enough hints to do further research and find more details in your crash dump.
You seem to have 230 stacks with a total of 2.5 GB of memory. That is about 11 MB of memory per stack. Usually that's limited to 1 MB.
I compiled the following program
using System;
using System.Runtime.InteropServices;
namespace SO55043889
{
class Program
{
public static int[] arr;
static IntPtr pointer;
static void Main()
{
const int GBSize = 1 * 1024 * 1024 * 1024/ sizeof(int);
Console.WriteLine("Allocating");
arr = new int[GBSize];
pointer = Marshal.AllocHGlobal(1024 * 1024 * 1024 );
Console.ReadLine();
Console.WriteLine(pointer.ToInt32() + arr[0]);
}
}
}
I ran the application and I attached to the process with WinDbg. I took a dump using
0:000> .dump /ma SO55043889.dmp
and now we can analyze it like this:
0:000> !address -summary
[...]
<unknown> 106 474f4000 ( 1.114 GB) 51.58% 27.86%
Heap 13 401e1000 ( 1.002 GB) 46.38% 25.05%
[...]
So we see 1 GB of (potentially) .NET memory and 1 GB of native memory.
0:000> .loadby sos clr
0:000> !dumpheap -stat
c0000005 Exception in C:\Windows\Microsoft.NET\Framework\v4.0.30319\sos.dumpheap debugger extension.
PC: 04f6fa73 VA: 00000000 R/W: 0 Parameter: 00000000
0:000> *** This is normal, just do it again
0:000> !dumpheap -stat
[...]
70d20958 12 1073742400 System.Int32[]
Total 335 objects
There are 12 int[] on the .NET side, taking a total of ~1 GB from the managed heap. Looking at the details, we see that there's only one big array and some smaller ones:
0:000> !dumpheap -type System.Int32[]
Address MT Size
020e1ff8 70d20958 300
020e2130 70d20958 24
020e2184 70d20958 40
020e2228 70d20958 80
020e2d9c 70d20958 16
020e2dac 70d20958 16
020e2df8 70d20958 16
020e386c 70d20958 24
020e3d54 70d20958 16
020e3d64 70d20958 16
020e3d74 70d20958 16
04811010 70d20958 1073741836
Statistics:
MT Count TotalSize Class Name
70d20958 12 1073742400 System.Int32[]
Total 12 objects
That's not what you wanted know. I just showed you how easy it is on the .NET side.
Now the native side:
0:004> !heap -s
LFH Key : 0x7f8d0cc6
Termination on corruption : ENABLED
Heap Flags Reserv Commit Virt Free List UCR Virt Lock Fast
(k) (k) (k) (k) length blocks cont. heap
-----------------------------------------------------------------------------
Virtual block: 80010000 - 80010000 (size 00000000)
00550000 00000002 1024 504 1024 14 17 1 1 0 LFH
002d0000 00001002 64 16 64 2 2 1 0 0
00820000 00041002 256 4 256 2 1 1 0 0
00750000 00001002 64 20 64 7 2 1 0 0
00710000 00001002 256 4 256 0 1 1 0 0
001e0000 00041002 256 4 256 2 1 1 0 0
-----------------------------------------------------------------------------
We can't see the 1 GB here. And there's a reason for that.
As explained before, heap managers are good at dividing large blocks from VirtualAlloc() (which are 64kB) into smaller pieces. They do that because it would be a big waste to allocate 64kB just for a 4 byte int. However, there's no need to create heap management stucture for large blocks. For an allocation of 2^30+1 byte, the OS would return 2^30+64kB, which means the overhead is just 0.006%.
That's why you will find allocations >512kB not inside the usual heap management structures but as a Virtual block, which means that the Windows Heap Manager has simply forwarded the request to VirtualAlloc().
There's another issue here: the output for the size is broken. It says
(size 00000000)
which obviously is not true. Let's look at it ourselves:
0:004> !address 80010000
Usage: Heap
Base Address: 80010000
End Address: c0011000
Region Size: 40001000
[...]
0:004> ? c0011000-80010000
Evaluate expression: 1073745920 = 40001000
What we see here is that End Adress - Base Address equals the Region Size and the size is 1 GB.
At this point, it's worth noting that the user mode stack trace database is useless. It only applies to items on the heap, but not VirtualAlloc(). You'll not figure out who allocated the 1 GB block.
And I forgot to enable the user mode stack trace database anyway. Let's do that and cross check
0:000> !gflag
Current NtGlobalFlag contents: 0x00001000
ust - Create user mode stack trace database
And now, there should be stack traces for smaller pieces of memory. In this example, I use an arbitrary block of size 0x208:
0:000> !heap -flt s 208
_HEAP @ 2a0000
HEAP_ENTRY Size Prev Flags UserPtr UserSize - state
002c9818 0044 0000 [00] 002c9830 00208 - (busy)
002cd1e8 0044 0044 [00] 002cd200 00208 - (busy)
002d5ad0 0044 0044 [00] 002d5ae8 00208 - (busy)
002f0c48 0044 0044 [00] 002f0c60 00208 - (busy)
0032c210 0044 0044 [00] 0032c228 00208 - (busy)
00351c90 0044 0044 [00] 00351ca8 00208 - (busy)
0:000> *** Use any UserPtr number, I use the last one
0:000> !heap -p -a 00351ca8
address 00351ca8 found in
_HEAP @ 2a0000
HEAP_ENTRY Size Prev Flags UserPtr UserSize - state
00351c90 0044 0000 [00] 00351ca8 00208 - (busy)
779dd909 ntdll!RtlAllocateHeap+0x00000274
71e18bc7 clr!EEHeapAlloc+0x0000002c
71e18c0a clr!EEHeapAllocInProcessHeap+0x0000005b
71e18ba6 clr!ClrAllocInProcessHeap+0x00000023
71e2dd26 clr!StackingAllocator::AllocNewBlockForBytes+0x00000082
71e2dd76 clr!operator new+0x00000063
71e93ace clr!MethodTableBuilder::BuildMethodTableThrowing+0x00000059
71e94590 clr!ClassLoader::CreateTypeHandleForTypeDefThrowing+0x0000083a
71e2e956 clr!ClassLoader::CreateTypeHandleForTypeKey+0x000000ad
71e2e99a clr!ClassLoader::DoIncrementalLoad+0x000000c2
71e2e418 clr!ClassLoader::LoadTypeHandleForTypeKey_Body+0x00000505
71e2e5a7 clr!ClassLoader::LoadTypeHandleForTypeKey+0x000000b5
71e2f723 clr!ClassLoader::LoadTypeDefThrowing+0x00000318
71e2a974 clr!ClassLoader::LoadTypeDefOrRefThrowing+0x0000024c
71f57811 clr!Assembly::GetEntryPoint+0x0000022f
71f856e0 clr!Assembly::ExecuteMainMethod+0x000000b3
71f855ed clr!SystemDomain::ExecuteMainMethod+0x00000631
71f858d3 clr!ExecuteEXE+0x0000004c
71f85819 clr!_CorExeMainInternal+0x000000dc
71f55a0c clr!_CorExeMain+0x0000004d
7251d93b mscoreei!_CorExeMain+0x0000010e
72597f16 MSCOREE!ShellShim__CorExeMain+0x00000099
72594de3 MSCOREE!_CorExeMain_Exported+0x00000008
77999802 ntdll!__RtlUserThreadStart+0x00000070
779997d5 ntdll!_RtlUserThreadStart+0x0000001b
Just one more note: if you modify the program to have smaller blocks of memory, e.g.
for (int i = 0; i < 1000; i++)
{
pointer = Marshal.AllocHGlobal(3*1024 );
}
You will see the allocation in the heap:
0:004> ? 3*0n1024
Evaluate expression: 3072 = 00000c00
0:004> !heap -flt c00
cound not parse flt criteria -flt c00
0:004> !heap -flt s c00
_HEAP @ 67c0000
HEAP_ENTRY Size Prev Flags UserPtr UserSize - state
0686b668 0183 0000 [00] 0686b680 00c00 - (busy)
0686efa8 0183 0183 [00] 0686efc0 00c00 - (busy)
[...]
And you will see stack traces
0:004> !heap -p -a 4d0fdf18
address 4d0fdf18 found in
_HEAP @ 67c0000
HEAP_ENTRY Size Prev Flags UserPtr UserSize - state
4d0fdf00 0191 0000 [00] 4d0fdf18 00c00 - (busy)
779dd909 ntdll!RtlAllocateHeap+0x00000274
768f5aae KERNELBASE!LocalAlloc+0x0000005f
70c6ad4f mscorlib_ni+0x003fad4f
7138c4da mscorlib_ni+0x00b1c4da
71e0ebb6 clr!CallDescrWorkerInternal+0x00000034
71e11e10 clr!CallDescrWorkerWithHandler+0x0000006b
71e17994 clr!MethodDescCallSite::CallTargetWorker+0x0000016a
71f85026 clr!RunMain+0x000001ad
71f85707 clr!Assembly::ExecuteMainMethod+0x00000124
[...]
But you won't see the managed method calls. That's because the USt database was built for native only. It's the same reason you have different stacks in .NET using k or !dumpstack.