dotNETInspector Tips & Tricks for Faster DebuggingDebugging .NET applications can be time-consuming, especially in large codebases or when confronting subtle runtime issues. dotNETInspector is a powerful tool that simplifies inspecting assemblies, analyzing types, and tracing execution paths. This article compiles practical tips and tricks that help you get the most out of dotNETInspector and speed up your debugging workflow.
What dotNETInspector does best
dotNETInspector focuses on static and runtime inspection of .NET assemblies. It exposes metadata, IL code, method bodies, and type hierarchies in an easy-to-navigate UI (or via command-line interfaces in some implementations). Use it to quickly find mismatched signatures, hidden dependencies, or suspicious IL constructs that are hard to spot in high-level code.
Key fact: dotNETInspector helps you inspect assemblies, view IL, and analyze type and method metadata.
Setup and configuration tips
- Start with the latest stable release of dotNETInspector to get performance improvements and bug fixes.
- Keep your symbol (.pdb) files alongside assemblies whenever possible — they provide richer method and variable names and improve traceability.
- Configure source mappings if your PDBs reference source paths that differ from your local workspace; this makes stack traces and navigation point to correct files.
- If working across multiple target frameworks, add each target’s assemblies to a dedicated project workspace to avoid type resolution conflicts.
Quick navigation tricks
- Use the type hierarchy view to jump from interfaces to implementations quickly — this helps when behavior originates in a derived class you didn’t expect.
- Filter by namespace or assembly when searching to reduce noise in large solutions.
- Pin frequently inspected types or methods to avoid repeated searches during an investigative session.
Inspecting IL and method bodies efficiently
- When investigating unexpected behavior, open the method’s IL to confirm what the compiler generated. Compiler optimizations or async/iterator transformations often produce IL that’s surprising compared to source code.
- Look for patterns like suspicious use of reflection, dynamic invocation, or late-bound calls — these often appear as MethodInfo.Invoke, Type.InvokeMember, or use of System.Reflection.Emit.
- Use IL differences between versions to pinpoint where a bug was introduced. Export method IL from two builds and diff them.
Diagnosing exceptions and stack traces
- Load the assembly and associated PDBs, then paste the raw stack trace into the search or “go to” box — dotNETInspector can often map frames back to exact IL offsets and source lines.
- When you see MissingMethodException or TypeLoadException, inspect assembly references and public token mismatches. Check for assembly binding redirects or mismatched versions in dependent assemblies.
- For FirstChanceException noise, identify the throwing method and inspect how exceptions are handled (or swallowed) by higher-level code paths.
Using symbol information to your advantage
- PDB-guided navigation makes it much easier to find local variable names and original source lines — invaluable when a decompiled body has compiler-generated names.
- Portable PDBs are often easier to distribute with builds and work across platforms. Ensure dotNETInspector is configured to read the PDB format you produce.
Root-cause analysis with call graphs and dependency views
- Generate call graphs for suspicious methods to see callers and callees. This quickly reveals unexpected entry points or performance hotspots.
- Use dependency views to find transitive dependencies that might introduce version conflicts or cause runtime binding issues.
- Annotate or export graphs to share with teammates — a visual can shorten debugging discussions.
Performance-focused inspections
- Identify large object allocations or heavy-use methods by correlating hotspots from your profiler with method bodies in dotNETInspector — inspect loops, allocations, and boxing conversions in IL.
- Look for unnecessary closure allocations created by lambdas that capture outer variables. These are often visible in IL as compiler-generated classes (e.g., display classes).
Dealing with obfuscated or minimized assemblies
- If names are obfuscated, focus on IL patterns, call relationships, string constants, and resource usage to infer purpose.
- Reconstruct likely method responsibilities by combining IL reading with runtime traces (logging or stack dumps) to map behaviors back to obfuscated identifiers.
Automated checks and scripting (if supported)
- Use built-in scripting or command-line modes (if your dotNETInspector build provides them) to automate repetitive inspections: scan assemblies for usages of dangerous APIs, reflection, or P/Invoke calls.
- Batch-export metadata (type lists, method signatures) for offline analysis or input to other tools like diff utilities or code-quality checks.
Integrating with your debugging workflow
- Combine dotNETInspector with a runtime debugger: find suspicious IL or method implementations and set breakpoints at the corresponding source or IL offsets in Visual Studio or your debugger of choice.
- Use logging to capture runtime values, then inspect the code paths in dotNETInspector that produced those logs to narrow down the cause.
Collaboration and knowledge sharing
- Export annotated views or screenshots of type hierarchies and method IL when filing bug reports. A precise pointer to an IL instruction or method metadata reduces back-and-forth.
- Maintain a short internal cheat sheet of common IL patterns your team has seen (e.g., async state machine markers, iterator patterns, common reflection idioms).
Common pitfalls and how to avoid them
- Pitfall: Relying solely on decompiled C# — Decompiled code can be misleading. Always verify suspicious behavior in IL.
- Pitfall: Ignoring PDB mismatches — ensure PDBs match the assemblies you’re inspecting. Mismatched symbols can mislead navigation.
- Pitfall: Overlooking transitive dependencies — a runtime failure often stems from an indirect dependency; use dependency views and binding logs.
Example workflows
- Crash analysis:
- Load assembly + PDBs, paste stack trace, map to source/IL, inspect method IL at failing offset, check callers and related types, verify referenced assembly versions.
- Performance mystery:
- Identify hotspot in profiler, open method in dotNETInspector, inspect loops and allocations in IL, search for boxing/closure allocations, refactor and verify in profiling runs.
- Strange behavior after upgrade:
- Load old and new assemblies, export IL or metadata for suspect methods, diff to locate changes, focus testing on modified code paths.
Final tips
- Keep exploring IL patterns — much of what appears “weird” in behavior is explained by compiler transformations visible only in IL.
- Use dotNETInspector in tandem with profilers, debuggers, and logs — each tool provides a different lens onto the problem.
If you want, I can expand any section into a deeper walkthrough (example: step-by-step crash analysis with screenshots and commands) or provide specific IL examples for async/iterator transformations.
Leave a Reply