标签：#dotnet

Overview PageRank is the canonical graph algorithm. NetworkX implements it in pure Python — its dict-of-dict adjacency representation means every power-iteration step dispatches millions of Python attribute lookups. When the graph has 1.8 million nodes and 28.5 million edges (Wikipedia category hyperlinks), those lookups dominate the runtime. The .NET replacement uses a CSR (Compressed Sparse Row) matrix — two flat int[] arrays for the graph structure — and TensorPrimitives for the SIMD-accelerated normalization step inside each iteration. Benchmark Setup Five SNAP datasets of increasing size: Dataset Nodes Edges wiki-Vote 7,115 103,689 soc-Epinions1 75,879 508,837 web-Stanford 281,903 2,312,497 web-Google 875,713 5,105,039 wiki-topcats 1,791,489 28,511,807 Algorithm: power-iteration PageRank, damping=0.85, tol=1e-6. Both implementations converge to identical top-10 node rankings. Results Dataset Python (NetworkX) .NET (CSR) Speedup wiki-Vote (103k edges) ~0.8 s ~100 ms ~8× soc-Epinions1 (508k edges) ~8 s ~600 ms ~13× web-Stanford (2.3M edges) ~120 s ~5 s ~24× web-Google (5.1M edges) ~5.5 min ~12 s ~28× wiki-topcats (28.5M edges) ~47 min ~60 s ~47× The speedup grows with graph size because NetworkX's Python dispatch cost scales with edge count, while the CSR inner loop is a tight JIT-compiled SIMD pass. Why CSR Beats NetworkX NetworkX represents each node's neighbors as a Python dict. Iterating the adjacency in one power-iteration step means: Calling G.neighbors(node) — a Python method call Iterating a dict — unboxing int keys, chasing heap pointers Accumulating a float into another dict value — another boxing step That happens for every edge, every iteration, roughly 50–80 times to convergence. CSR collapses the graph to two arrays: rowPtr[n+1] (where each node's neighbors start) and colIdx[edges] (the neighbor list). Iterating neighbors of node v is a tight C loop from rowPtr[v] to rowPtr[v+1] . No Python objects, no dict hashing, no pointer chasing. Key Code // P

This article will teach you how to export any list into Excel in C# using the ClosedXML library. Steps to complete Create the data model with dummy data that we'll export into Excel. Create ExportExcel interface methods that accept any type of List (using IEnumerable<T> ) and a Dictionary List and export a byte array. Create extension methods and convert the provided data into rows and columns (using DataTable ). Create a service class that implements the interface methods and export the data table into a Memory Stream (byte array) using ClosedXML . Create one API endpoint that exports data in memory into Excel. Create another endpoint that exports incoming (custom) request data into Excel. Wire up dependencies. Project structure ├── Program.cs ← Project startup & dependency injection │ ├── controllers / │ └── ExportToExcelController.cs ← API entry point ├── services / │ ├── IExportToExcelService.cs ← Export Excel interface │ └── ExportToExcelService.cs ← Export Excel concrete class │ ├── models / │ ├── Car.cs ← Car class definition & dummy data │ ├── ExcelResponse.cs ← Wrapper class for excel file name and data │ └── ExportExcelRequest.cs ← Request class for that accepts any kind of list that will be exported │ └── extensions / └── IEnumerableExtensions.cs ← Extension methods for List<T> and List<Dictionary> 1️⃣ Data model I've created the dummy data model to demonstrate the dynamic implementation. public enum FuelType { Petrol, Diesel, Electric, Hybrid } public class Car { public Guid Id { get; set; } public string Name { get; set; } public string Manufacturer { get; set; } public int YearProduced { get; set; } public string Color { get; set; } public FuelType FuelType { get; set; } public int HorsePower { get; set; } public int NumberOfDoors { get; set; } public bool AutomaticTransmission { get; set; } public double AverageFuelConsumption { get; set; } public int MaxSpeed { get; set; } public decimal Price { get; set; } public static List<Car> GetCars() { ... } }

It is straightforward to configure a minimal API to produce an OpenAPI document at build time . This runs the API during build, requests the OpenAPI document from it, and saves it to disk. The slightly trickier part is to put checks in Program.cs to exclude any startup code that cannot run at build time. This is typically done because configuration key/value pairs are not available at that time. For example: if (! isBuildTime ) { connString = builder . Configuration . GetConnectionString ( "AppDB" ) ?? throw new InvalidOperationException ( "Connection string 'AppDB' is not configured." ); builder . Services . AddDbContext < AppDbContext >( options => { options . UseNpgsql ( connString ); } ); } The question is how to deduce that the API has been launched at build time, i.e. isBuildTime should be true? The official way of doing this is to check that the assembly that invoked the API is "GetDocument.Insider" : var isBuildTime = Assembly . GetEntryAssembly ()?. GetName (). Name == "GetDocument.Insider" ; GetDocument.Insider.dll is the command line tool that automatically runs during build of the API if the .csproj includes the following reference: <PackageReference Include= "Microsoft.Extensions.ApiDescription.Server" Version= "10.0.7" > ... </PackageReference> This package is a shim. It only provides build targets and props and hooks into the build of the API to run the command-line tool dotnet-getdocument . This tool in turn runs the command line tool GetDocument.Insider that we check for. This is a pretty convoluted sequence: Microsoft.Extensions.ApiDescription.Server provides targets that run during build of the API. One of those targets runs the command line tool dotnet-getdocument That in turn runs the command line tool GetDocument.Insider That in turn runs the API and fetches the /openapi/v1/json (or other configured endpoint) to get the OpenAPI document and saves it to disk. Checking in Program.cs if the API was invoked by the assembly GetDocument.Insider.dll t

OpenTelemetry has quietly become table stakes. That's a good thing, but if you've instrumented a real codebase, you know the tax. A method that does one obvious thing slowly fills up with StartActivity , SetTag , AddEvent , SetStatus . The bookkeeping of telemetry starts to drown out the intent of the code, and in review you spend half your time mentally separating "what this code does" from "what we report about what it does." It's easy to think "oh, but the framework takes care of this with auto-instrumentation", but if you talk to the experts in OTel, they'll go to great lengths to explain that auto-instrumentation is a floor, not a ceiling. Most of the value in telemetry comes from the custom instrumentation you add to your code that adds business context to your traces. And that custom instrumentation is the stuff that clutters up your code. Here's the kind of thing I mean: // before - ugly, obtuse, who put that there var orderId = order . Id ; Activity . Current ?. SetTag ( "orderId" , orderId ); Sidemark is my answer to that code-obfuscation problem: non-invasive instrumentation via what I'm calling Active Comments . // after - glorious, beautiful, basking in the light of the sun, closer to god, happy, satiated var orderId = order . Id ; //? The idea A small set of comment syntaxes - //? , //! , //?! - become ride-along annotations . They travel next to the code, get read at build time, and turn into the equivalent Activity calls in the compiled output. The code you read stays the code that does the work. The telemetry rides along instead of competing with your logic for attention. The framing is loosely inspired by Wallaby.js's Live Annotations , which project runtime values inline next to the code that produced them. Sidemark takes the same instinct in the other direction: comments as a write surface for instrumentation, rather than a read surface for debug values. Comments are an under-used channel for information about code that isn't itself code - and su