Serilog vs log4net vs NLog - Detailed Comparison
Tags: csharp, dotnet, programming, productivity
Published: 2023-09-20 12:20:17

When developing robust .NET applications, inevitably, you will need an efficient and reliable logging mechanism. Lucky for you, you’ve got options. But how to choose? Let’s dive into the world of logging libraries and compare three of the most popular: [Serilog](https://www.bytehide.com/blog/serilog), log4net, and NLog.

## Introduction

Logging often seems an afterthought, right? Who has time to organize logs when you’re trying to debug that stubborn piece of code that just won’t behave. But trust me, having a [solid](https://www.bytehide.com/blog/solid-principles-in-csharp) logging system can save you a mountain of hair-pulling frustration later. So, why not invest some time understanding your options?

### Brief Overview of Logging Libraries

In the .NET landscape, there are three major players when it comes to logging libraries: Serilog, log4net, and NLog. Each comes with its unique flavor and set of gimmicks. So, buckle up, my fellow coder, as we take a speed tour through the wild west of .NET logging.

## Serilog

Let’s delve deeper into Serilog. We’re about to uncover more functionalities, explain how Serilog stands out from its counterparts, and explore how its features can be best applied in real-world scenarios.

### What is Serilog in .NET?

From the name, you’d think it’s just about ‘logging’ — messages that developers record during the execution of a programme to understand its flow. But with Serilog, there’s more than meets the eye. It not only takes logging to a new level with its “structured logging” but also simplifies log events to make them easily queryable.

```csharp
// Using Serilog
Log.Logger = new LoggerConfiguration()
    .WriteTo.Console()
    .CreateLogger();

Log.Information("Hello, Serilog!"); 

// Creates structured log data
Log.Information("Order {OrderId} created for {CustomerId}", orderId, customerId);
```

In the above example, we’re going beyond logging a simple string message. Serilog allows us to create more complex log entries, associating specific data with each log entry. Suddenly, our logs are more than just a written record; they are “structured”!

Imagine it like you’re jotting down notes but instead of a block of text, you have specific fields like ‘OrderId’ and ‘CustomerId’. Now, wouldn’t that make it easier to reference your notes later on?

#### Understanding Serilog Functionality

If you’re still here, it means you’re not just teasing me; you’re genuinely interested in Serilog. Are you ready for the next level? Brace yourself, we’re about to dive into the ‘black hole’ of ‘Serilog de-structuring’!

```csharp
// Serilog De-structuring
Log.Information("Processing {@Order}", order);
```

In this example, we use an ‘@’ symbol in front of the Order object. This means that Serilog will de-construct the ‘order’ object and log the public properties of the object. Let’s decompose this further:

Assume you have a complex object (let’s call it an ‘order’), which has many properties like ‘OrderId’, ‘OrderName’, ‘OrderStatus’, and so on. Now, when you log this object, conventionally, you’d get the type name of the object, right? Not very helpful, huh?

Here’s where the ‘@’ operator comes to your rescue. It tells Serilog: “Hey, don’t just tell me the type name! De-construct it and log the properties. I want them all!”

```csharp
// Order class with public properties
public class Order
{
    public int OrderId { get; set; }
    public string OrderName { get; set; }
    public string OrderStatus { get; set; }
}

// Create an instance of an order
Order order = new Order { OrderId = 1001, OrderName = "New Laptop", OrderStatus = "Processing" };

// Using Serilog De-structuring
Log.Information("Processing {@Order}", order);
```

Guess what the output will be? It’d not log the type name of ‘order’ but rather the values of the properties of the ‘order’ object. Imagine being able to readily reference all the details instead of just the type name!

### Advantages of Serilog

Alright, you’ve endured me chattering about ‘Serilog’, its ‘structured logging’, and ‘de-structuring’. Now, let’s unwrap the advantages of employing this wonderful log library in our applications.

#### Features Offering Significant Advantages

-   **Structured Logging**: This is like giving superpowers to your logs. Having everything structured and organized makes querying your logs a dream come true.
-   **Wide Support of Sinks**: Logging to a console or a file feels old-school, right? Serilog brings modernity by supporting a wide [array](https://www.bytehide.com/blog/array-csharp) of sinks (destinations), including several popular databases, log management systems, and even cloud-based log services.
-   **Configuration Options**: Be it from a configuration file or programmatically, Serilog lets you set up your logger as you fancy.

#### Real-world Applications of Serilog

Even the Joker would agree, our beloved Serilog is no joke when it comes to managing logs in real-world applications. If you’ve got multiple services running and communicating, correlating logs from all these services could be a headache worse than your worst hangover.

Enter Serilog! Using structured logging, you could effortlessly log request IDs or even usernames. So debugging becomes a cakewalk, even in complex distributed systems.

**Picture this**: You’re running an online store. Every time an order comes, different services process different aspects. If you want to know the flow of a specific order, structured logging with Serilog is your best friend. Store ‘OrderId’ and trace it like a detective following a trail.

### Disadvantages of Serilog

There are two sides to every coin, and Serilog isn’t an [exception](https://www.bytehide.com/blog/5-good-practices-for-error-handling-in-c).

-   It requires .NET 4.5 or higher, so if you’re holding onto older .NET versions, this might not be your cup of tea.
-   If your logging needs are simple and you’re dealing with plain text logging, Serilog could be like hiring a rocket scientist to tutor a kindergartner.

## log4net

Day two of our tour around the logging landscape, and it’s all about log4net today. Even if you’re newer to the scene, there’s a good chance you’ve heard someone, somewhere, mention log4net. So let’s unwrap this package and explore the vintage charm of log4net.

### What is log4net in .NET?

Log4net, a seasoned veteran, has been serving the .NET community for over a decade. It is an adaptation of the well-renowned log4j library in Java. The reputation is well-earned, log4net provides flexibility like no other!

```csharp
// Using log4net
var log = LogManager.GetLogger(typeof(MyClass));
log.Info("Hello, log4net!");

// Also support for different levels of logging
log.Debug("Debugging");
log.Error("Something went wrong!");
```

In the above example, log4net provides different logging levels ranging from Info to Error.

Isn’t it just fabulous how it contorts and moulds itself according to your requirements? Reminds me of my favourite yogi!

#### Understanding How log4net Works

The power of log4net lies in its XML configuration file. It gives you total control over log4net’s operations. Need to switch up your logging tactics in the middle of everything? You can do that in a snap, just like switching lanes on an open highway!

```xml
<log4net>
  <root>
    <level value="DEBUG" />
    <appender-ref ref="consoleAppender" />
  </root>
  <appender name="consoleAppender" type="log4net.Appender.ConsoleAppender">
    <layout type="log4net.Layout.PatternLayout">
      <conversionPattern value="%date [%thread] %-5level %logger - %message%newline" />
    </layout>
  </appender>
</log4net>
```

In this XML configuration, we’re instructing log4net to log DEBUG level and above logs onto a console. The `conversionPattern` is where you control the format of the output log message. Much like your favourite ice cream store, mix and match to satisfy your taste buds!

### Pros of Using log4net

log4net sneaks an all-access pass to control your logging style, arguably its most appealing attribute. Let’s find out what more it can offer.

#### Features of log4net

-   **Flexibility:** log4net adapts to multiple scenarios. Writing logs to a text file? Easy peasy. Logging directly to a data store? It’s a child’s play. Juggling both of them together? Why not! Have it your way!

```xml
<appender name="RollingFile" type="log4net.Appender.RollingFileAppender">
    <file value="myapp-log.txt" />
    <rollingStyle value="Size" />
    <maximumFileSize value="10MB" />
    <staticLogFileName value="true" />
</appender>
<appender name="AdoNetAppender" type="log4net.Appender.AdoNetAppender">
    <connectionType value="System.Data.SqlClient.SqlConnection, System.Data" />
    <connectionString value="data source=[datasource];initial catalog=[database];integrated security=false;" />
    //...Other settings omitted for brevity
</appender>
```

With two simple appender tags, we can log our data to a file and a database simultaneously. Now that’s what I call hitting two birds with one stone!

-   **Mature and Stable:** Being around for a while has its advantages, fewer bugs, widespread acceptance, and tremendous community support, to mention a few.

#### Successful Implementations of log4net

Over time, log4net has found homes in many real-world applications. Its emphasis on customization and adaptability make it a popular choice for systems requiring granular control over logging.

Remember, our good ol buddy who was perpetually late to work? Yeah, whoever comes to your mind. log4net is like his alarm clock which he could snooze, dim, brighten, set to soothing bird chirp, loud jarring horns or what have you. In our case, we can configure the type of logs, the level of severity, and where to record these logs.

### Cons of Using log4net

So far, we only talked sunshine and rainbows. But, remember what Uncle Ben advised Peter? “With great power, comes great responsibility!”. And with log4net, it’s no exception.

-   **Lack of structured logging:** Compared to Serilog, extracting meaningful information from logs can seem like looking for a needle in a haystack. Sigh!
-   **Configurations complexity:** While using XML for configurations does open the door to countless opportunities, the catch is, it gets more complicated as your requirements unfold. Try explaining a Knapsack problem to an 8-year old, you’ll get the drift!

So, when considering log4net, always remember the sushi master analogy. Sure, having a do-it-yourself sushi set is fun, but only if you know how to make sushi. Otherwise, it might get messy!

## NLog

Let’s talk about NLog. Often compared as the younger cousin of log4net and the lesser-known rival of Serilog, NLog offers a unique blend of features on its own. It shares a brotherly bond with log4net when it comes to flexibility and agrees with Serilog on structured logging. So buckle up! We are about to explore more on what makes NLog a worthy contender.

### What is NLog?

I like to think of NLog as a bridge between the sophistry of Serilog and the tried-and-tested nature of log4net. It supports structured logging while still maintaining a high level of adaptability in terms of where and how logs can be stored. Basically, it’s got the chops of both Serilog and log4net.

```csharp
// Initialize NLog Logger
var logger = NLog.LogManager.GetCurrentClassLogger();
// Logging an informational message
logger.Info("Greetings from NLog World!");
```

The above example depicts a logger instance being created using NLog. The `GetCurrentClassLogger` method ensures that the logger instance is assigned to the current class, and subsequently, an informational log is recorded.

#### Deep Dive into NLog’s Functions

NLog delivers the best of both worlds—structured logging and XML-driven configuration—without any condescending compromises.

```csharp
// NLog – Illustrating structured logging
logger.Info("Just dispatched an order {OrderId} to client {ClientId} ", 1200, "C100");
```

These simple lines can log comprehensive information that’s relatively easier to process later. Notice how we pass the unique numeric `OrderId` and alphanumeric `ClientId` directly to the log message? Well, this is exactly what we mean by structured logging.

### Benefits of Using NLog

NLog might seem like a new kid on the block compared to its peers, but what it brings on the table is fresh and adaptable.

#### Key Features of NLog

-   **Structured Logging**: Not as distinct as Serilog but it gets the job done without adding additional overhead.
-   **Flexibility**: In terms of configurability and defining log outputs (file, console, database, or email), NLog is as flexible as log4net.

```csharp
// NLog – Configuring multiple log targets
var config = new NLog.Config.LoggingConfiguration();

// Targets for logging - File and Console
var logfile = new NLog.Targets.FileTarget("logfile") { FileName = "log.txt" };
var logconsole = new NLog.Targets.ConsoleTarget("logconsole");

// Rules for mapping loggers to targets 
config.AddRule(LogLevel.Info, LogLevel.Fatal, logconsole);
config.AddRule(LogLevel.Debug, LogLevel.Fatal, logfile);

// Apply config
NLog.LogManager.Configuration = config;
```

The given code provides a scenario where NLog configures two targets for logging, i.e. `logconsole` and `logfile`. The `AddRule` function is what maps specific log levels to targeted outputs.

#### Examples of NLog’s Practical Uses

Where exactly does NLog shine? It’s the go-to choice for projects that require structured logging features without taking the computational hit that can come with Serilog. On top of that, NLog performs better in throttling scenarios where log generation is considerably high.

### Downsides of NLog

While NLog is a capable contender, it still has certain areas where improvements are welcomed:

-   Comparatively less mature than log4net; it has been around for a shorter time.
-   Although it has structured logging, it is not as evolved or sophisticated as Serilog. Hence, if structured logging is your top priority, you might want to explore Serilog as well.

To exemplify, imagine explaining your like your favorite ice cream flavor. You wouldn’t just say “it’s sweet.” You’d likely give specific details—maybe it’s creamy, or it has chunks of cookie dough, or it reminds you of fun summer days.

NLog is like the description—it doesn’t just say, “something was logged.” It provides the additional context you need to fully understand the log event.

## Comparison: Serilog vs log4net vs NLog

Are you ready for the main event? Three heavyweight champions of the .NET logging world are about to face off. In this corner, presenting the nice guy of structured logging, Serilog. Duping it in the middle, the elder statesman, log4net. And squaring off last but not the least, the flexible contender, NLog.

### Feature Comparison

Let’s get down to the nitty-gritty. Comparing logging libraries might sound as [dry](https://www.bytehide.com/blog/dry-principle-csharp) as unbuttered toast, but hey, who said programming was always action-packed, right?

First and foremost, does your application require structured logging? If yes, Serilog is gonna be your best friend. Let’s revisit why Serilog is structured logging’s poster child:

```csharp
// Serilog Structured logging
Log.Information("Order {OrderId} created for {CustomerId}", orderId, customerId);
```

These logs are automatically structured into key-value pairs, making it easy to filter based on specific properties. Let me remind you… This is pure gold when debugging!

Now, if your application doesn’t really need structured logging, but configurable logging is what you’re after, log4net has been doing this forever:

```csharp
// Using log4net
var log = LogManager.GetLogger(typeof(MyClass));
log.Info("Hello, log4net!");
```

With log4net, you can configure what you log and where it’s logged.

Meanwhile, NLog caters to best of both worlds, balancing structured logging and high configurability:

```csharp
// NLog structured logging
logger.Info("Order {OrderId} created for {CustomerId}", orderId, customerId);
```

Just like Serilog, NLog supports structured logging and like log4net, it offers high configurability. A true balance of power, if you ask me.

Here’s a taste of the feature comparison:

| Feature | Serilog | log4net | NLog |
| --- | --- | --- | --- |
| Structured Logging | ✅ | ❌ | ✅ |
| High Configurability | ✅ | ✅ | ✅ |
| Good Performance | ✅ | ✅ | ✅ |

### Performance Comparison

Performance is like the silent panther, unnoticed until it pounces. All three offer comparable performance. But when it comes to structured and high throughput logging, both Serilog and NLog have a slight edge over log4net.

| Performance Aspect | Serilog | log4net | NLog |
| --- | --- | --- | --- |
| Structured Logging Performance | 🔥🔥🔥 | 🔥🔥 | 🔥🔥🔥 |
| High Throughput Logging Performance | 🔥🔥🔥 | 🔥🔥 | 🔥🔥🔥 |
| General Logging Performance | 🔥🔥🔥 | 🔥🔥🔥 | 🔥🔥🔥 |

### Community Support Comparison

Ever gotten stuck with a piece of software that no longer has any support? Feels like being alone in the rain. Good news though, all three libraries have a strong community backing. However, Serilog and NLog have more active development, since they cater to more modern logging needs.

| Logging Library | Community Support |
| --- | --- |
| Serilog | 🔥🔥🔥 |
| log4net | 🔥🔥 |
| NLog | 🔥🔥🔥 |


## The Verdict: Serilog, log4net, or NLog?

Choosing between Serilog, log4net, and NLog is like choosing between playing soccer, basketball, or doing a biathlon. They are fundamentally different, but each brings their unique advantages to the game.

Here’s another visualization to think about. Imagine our codebase is a pretty sophisticated city, and logs are vehicles driving through it. Serilog would then be our supercar, perfect for highways (or structured logging), because it’s built for excellent performance and speed, with the bonus of being flashy.

```csharp
// Serilog: Speeding up your structured log queries
Log.Logger = new LoggerConfiguration()
    .WriteTo.Console() 
    .CreateLogger();

Log.Information("Processing {@Order} at {Time}", order, DateTime.Now);
```

Meanwhile, log4net is like a reliable truck. It may not be as flashy or speedy, but it is robust and trustworthy, cruising comfortably in our city, handling all the day-to-day logging jobs without breaking a sweat.

```csharp
// log4net: Reliable and gets the job done
var log = LogManager.GetLogger(typeof(MyClass));
log.Info("Performing the day to day logging tasks!");
```

Finally, NLog attempts to strike a balance, acting as an SUV that combines off-road ability and comfort, bridging the gap between Serilog’s structured logging brilliance and log4net’s uncomplicated durability.

```csharp
// NLog: Best of both worlds
var logger = NLog.LogManager.GetCurrentClassLogger();
logger.Info("Order {OrderId} named {OrderName} for {CustomerId}", orderId, orderName, customerId);
```

Sounds fun, right? But don’t jump to a conclusion just yet. As developers, our choices should always be guided by specific needs and our application’s context.

### Tips for Selecting the Right Logging Library

Choosing a logging library is a critical decision, but it doesn’t have to be as hard as hitting the jackpot in a lottery. Here are some pointers that might help focus your decision:

-   **Log contents**: What information will you log? Is it plain text, property-rich events, or both? Remember, Serilog is the standard-bearer for structured logging, NLog provides a balanced alternative, and log4net is your old-school logging champ.
-   **Library’s offer**: Consider the library’s ecosystem too. What logging outlets (file, console, database, cloud, etc.) are supported? How is the community support?
-   **Integrations**: Is your tech stack compatible with the library? For example, if you’re a fan of .NET Core’s built-in logging abstraction, both Serilog and NLog offer excellent integration.

```csharp
// Example: Integrating Serilog with the built-in .NET Core logging
Log.Logger = new LoggerConfiguration()
    .Enrich.FromLogContext()
    .WriteTo.Console()
    .CreateLogger();

WebHost.CreateDefaultBuilder(args)
    .UseSerilog()
    .Build();
```

-   **Performance and ease of use**: If your application handles a large number of logs, it’s necessary to ensure your selected library is not just fast, but simple to query and filter too.

Like a team selecting a perfect player for its next match, choose the logging library that stands out in the game your application is playing. Feast your eyes on the coding screen, flex your nimble fingers, and let them dance over the keyboard, creating perfect log notes on the canvas of your .NET application. Let the best logger win!