VS2017性能分析：模块名显示为GUID的内存增长问题咨询

Alright, let’s break down how to tackle this tricky scenario where your GC runs but memory still creeps up, and the top memory hog is an unnamed function (only a hex address) tied to that elusive GUID module {FAD2D840-B4A3-448C-8ED1-BA21B6695CDB}.

First, Demystify the GUID Module #

Since a Google search turns up nothing on that GUID, we need to investigate the module directly in your running process:

• List all loaded modules: Grab tools like Process Explorer (Windows) or lsof/pmap (Linux/macOS) to see every module your app has loaded. Sometimes dynamic modules—like in-process COM components, JIT-generated code, or even third-party plugin frameworks—show up with GUIDs instead of friendly names. Look for entries that map to that exact GUID.
• Dig into module metadata: If it’s a Windows PE file, use dumpbin /headers or sigcheck to pull details like the file path, version info, or embedded resources. For non-Windows systems, objdump or readelf can help unpack module details. Even dynamically generated modules might leave clues in profilers like dotTrace or Visual Studio Profiler about where they were loaded from.
• Check COM registration: GUIDs are a staple of COM components. On Windows, run this command in Command Prompt to see if the GUID is registered to a specific DLL:

  reg query HKEY_CLASSES_ROOT\CLSID\{FAD2D840-B4A3-448C-8ED1-BA21B6695CDB}
  

  This might point you to the actual component hiding behind that GUID.

Uncover the Unnamed Hex Address Function #

That hex address without a name isn’t a dead end—we can map it to real code:

• Enable symbol support in your profiler: If you’re using a .NET profiler, make sure symbol servers (Microsoft’s public server or your internal one) are turned on. Even if the module is unnamed, symbols might resolve the function if it’s part of a system component or your own code that wasn’t stripped of symbols.
• Capture and analyze a memory dump: Take a full memory dump when your app’s memory is high. Tools like WinDbg (Windows) or GDB (Linux) can load the dump and run commands like !dumpmodule (for .NET) or info symbol <hex-address> (native) to get context about the function. You might find it’s a helper from the runtime, generated code from a serializer, or part of an ORM library.
• Check for JIT-generated code: In .NET, older profilers sometimes show JIT-compiled methods as hex addresses instead of names. Use !jitminidump in WinDbg to pull details on JIT-generated methods, or switch to a newer profiler that handles JIT symbol resolution better.

Tackle the GC Memory Growth (Even After Collections) #

Since GC runs but memory still grows, focus on these angles:

• Trace object roots from the mysterious function: Take a heap snapshot with your profiler and follow the object references. The unnamed function might be holding onto objects in static fields, unexpiring caches, or unmanaged resources that aren’t being released properly.
• Check for unmanaged memory leaks: If that GUID module is a native component, it could be allocating unmanaged memory that the GC can’t track. Use tools like VMMap (Windows) or memstat (Linux) to compare managed heap size against unmanaged memory usage—if unmanaged memory is growing, that’s a clue.
• Inspect the finalizer queue: Run !finalizequeue in WinDbg to see if objects are stuck waiting to be finalized. If the mysterious function is tied to finalization logic, it might be blocking the queue, leading to memory buildup.

Exclusionary Approach for the Next Top Method #

If the unnamed function is a dead end, shift focus to the next exclusive method in your profiler results:

• Compare heap snapshots over time: Take snapshots at intervals as memory grows, then look for object types that are steadily increasing in count. Even if you can’t trace back to the GUID module, tracking growing object lists (like event handlers, cached data, or log entries) can lead you to the root cause.
• Disable suspect components one by one: If your app uses plugins, third-party libraries, or optional features, disable them individually and monitor memory usage. If the growth stops when a component is off, you’ve narrowed down your target.
• Hunt for resource leaks: Check for unclosed database connections, network sockets, file handles, or graphics resources. These often don’t show up directly in managed heap profilers but can cause indirect memory growth by keeping objects alive longer than necessary.

内容的提问来源于stack exchange，提问作者Yushatak