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Mark Farragher

Modern computers have loads of memory. But it's very easy to burn through it all in seconds if your code is not efficient about allocating and using memory.

Did you know that one simple mistake can make your code allocate 1600 times more memory than absolutely necessary?

Don't be 'that developer' who keeps crashing the development server with an OutOfMemory exception.

And you certainly don't want to be responsible for inflating the hardware budget. Can you imagine having to explain to your team that 512 GB of memory is not enough to run your code on the production server?

Let me help you.

Read more

Modern computers have loads of memory. But it's very easy to burn through it all in seconds if your code is not efficient about allocating and using memory.

Did you know that one simple mistake can make your code allocate 1600 times more memory than absolutely necessary?

Don't be 'that developer' who keeps crashing the development server with an OutOfMemory exception.

And you certainly don't want to be responsible for inflating the hardware budget. Can you imagine having to explain to your team that 512 GB of memory is not enough to run your code on the production server?

Let me help you.

It doesn't have to be like this. If you have a good understanding of the garbage collection process and follow a few simple best practices, you can dramatically reduce the memory footprint of your code.

Sound good?

In the last 10 years I have learned the secrets of garbage collection in .NET, and in this course I am going to share them all with you.

In a series of short lectures I will take a detailed look at the garbage collection process. I will show you all of the memory allocation problems you can expect when writing C# code, like unexpected boxing, string duplication, collection resizing, and more. I'll teach you quick and easy strategies to resolve these problems.

By the end of this course you will be able to master the garbage collector.

Why should you take this course?

You should take this course if you are a beginner or intermediate C# developer and want to take your skills to the next level. Garbage collection and memory management might sound complicated, but all of my lectures are very easy to follow and I explain all topics with clear code and many instructive diagrams. You'll have no trouble following along.

Or maybe you're working on a critical section of code in a C# project, and need to make sure your memory usage is as efficient as possible? The tips and tricks in this course will help you immensely.

Or maybe you're preparing for a C# related job interview? This course will give you an excellent foundation to answer any questions they might throw at you.

Enroll now

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What's inside

Learning objectives

  • Learn how the garbage collector works
  • Master .net memory optimization
  • Discover the truth about finalizers
  • Learn how to measure the memory footprint of your code
  • The unexpected memory footprint of list resizing
  • Structs versus classes - which one is better?
  • What assumptions does the gc make about object size and lifetime?
  • Manual deallocation with the dispose pattern
  • ... and much more!

Syllabus

Introduction

In this lecture I explain how this course is organised and I describe each of the upcoming sections in detail.

Read more

In this lecture I will tell a bit more about myself, my career, and my motivation to become an online trainer.

In this lecture we're going to look at the theory behind .NET memory management. What exactly is Garbage Collection, and how does it work?

Many lectures in this course contain source code examples. Feel free to download the code and follow along. And here's the good news: it doesn't matter if you have a Window, Mac or Linux computer. The code will run on all three operating systems.

In this lecture I demonstrate how my solutions and projects run on all operating systems. I will show you how to build and run the source code on a Mac, on Linux and in Visual Studio running on Windows 8.

At the end of this lecture you will have learned that .NET code is portable and can run on at least five different operating systems.

Welcome to the Fundamentals of .NET Memory Management section. I will give a quick introduction on how the section is organised before we get started.

This lesson will lay down some groundwork and explain in detail what the stack is for, and how data on the stack is laid out in memory.

After completing this lecture you will have learned which data is stored on the stack and what happens when this data goes out of scope. Finally, you will have seen a Stack Overflow exception, and know how to avoid this exception in your own code.

This lesson will lay down some groundwork and explain in detail what the heap is for, and how data on the heap is laid out in memory.

After completing this lecture you will have learned which data is stored on the heap and what happens when variables that refer to this data go out of scope. Finally, you will be able to explain what the 'Garbage collection' process does.

A popular question that often comes up in job interviews is: "what is the difference between a value type and a reference type?"

This lecture looks at value types in detail. What are value types, how do they store their data, and what happens when value types are assigned or compared? After completing this lecture you will be able to answer all of these questions with ease.

A popular question that often comes up in job interviews is: "what is the difference between a value type and a reference type?"

This lecture looks at reference types in detail. What are reference types, how do they store their data, and what happens when reference types are assigned or compared? After completing this lecture you will be able to answer all of these questions with ease.

Value types and reference types are both derived from the same common base class "Object". This is a nice feature of the .NET Framework, but behind the scenes it creates some problems for the runtime environment because reference types can never exist on the stack.

In this lecture you will learn how .NET uses a cool trick called "Boxing" to get around this problem. After completing the lecture you will be able to explain what boxing and unboxing is, and why it is neccesary.

Congratulations on finishing this section. This is a recap of what we have learned.

Welcome to the Detailed Look At Garbage Collection section. I will give a quick introduction on how the section is organised before we get started.

The .NET Garbage Collector is responsible for cleaning up all dereferenced objects on the heap. In this lecture we are going to take a long hard look at its internal architecture.

I will show you how the Garbage Collector uses a mark-and-sweep cycle to periodically clean the heap, how it uses generations to sort objects into short-living and long-living groups, and how it is specifically optimized for handling large objects.

After completing this lecture you will be able to describe in detail how the Garbage Collector works. You will also be aware of the assumptions it makes about object sizes and lifetimes.

In this lecture we're going to look at a couple of specific performance improvements you can make to your code, that will help you work with the Garbage Collector instead of against it.

We will look in detail at the assumptions the Garbage Collector makes about the size and lifetime of the objects in your code, and how you can take advantage of these assumptions by carefully designing your objects.

After completing this lecture you will have learned how to write fast and efficient code that works in harmony with the Garbage Collector.

In this lecture we are going to take a closer look at finalisers, which are special methods that are called by the .NET Garbage Collector just before an object gets deallocated. Finalisers offer a very convenient safety net for last-minute deallocation and disposing of resources held by the object.

But finalisers are dangerous and very hard to get right. I will show you three big disadvantages of finalisers in terms of code robustness and memory performance.

Sometimes an object needs to access scarce operating system resources, like a graphics device handle, a database connection, or a block of unmanaged memory. The Dispose pattern is an efficient design pattern in .NET to quickly release these resources when they are no longer needed.

In his lecture you will learn why the dispose pattern is much more efficient than simply releasing the resources in the finaliser, and I will also teach you how to write a reference implementation of the design pattern.

Congratulations on finishing this section. This is a recap of what we have learned.

Welcome to the Simple Tricks section. I will give a quick introduction on how the section is organised before we get started.

The .NET runtime uses a very cool trick called 'boxing' that allows you to use value types and reference types interchangeably in your code.

In this lecture I will use a test program to measure exact how much overhead the boxing operation introduces. You will see how to use the log profiler built into the Mono framework to track what the garbage collector is doing while the program is running.

After completing this lecture you will have learned why boxing is best avoided in mission-critical code.

Strings in .NET are immutable. This can introduce a large memory footprint when modifying strings, especially when done in a loop.

In this lecture I'll show you a test program that builds a string of 10,000 characters using either simple string concatenation, or the StringBuilder class. We will investigate exactly how much heap memory is allocated, how often the garbage collector runs, and which methods are called in each scenario.

By the end of the lecture you will have learned why you should always use a StringBuilder to modify strings in mission critical code.

Structs in C# are Value Types, which means they are allocated inline with other data, either on the stack or on the heap. This can save a lot of memory, especially if you quickly need to allocate millions of items.

In this lecture I will show you a test program that uses structs and classes to store a large amount of data. The struct- and class-based implementations will go head to head to determine which has the smallest memory footprint.

By the end of the lecture you will have learned in which scenarios a struct is the best choice for storing data.

Collections and lists in .NET automatically resize their internal buffer to accommodate the addition of new items. This is a very nice feature because it means you never have to worry about the size of your lists.

But successive resizes can litter the heap with dereferenced storage buffers and inflate the memory footprint of your code. I will demonstrate a program that fills a list with items and ends up allocating much more memory than it actually needs.

By the end of this lecture you will have learned a very simple trick to keep the memory allocation of lists and collections firmly under control.

LINQ is a nice feature of the C# language that lets you access enumerated data with a flexible and powerful query language. LINQ queries can access any data that supports the IEnumerable interface. But thoughtless use of LINQ can produce a large memory overhead and can significantly slow down your code.

In this lecture I will show you a spellchecker that uses LINQ and allocates way too much memory. Then I'll demonstrate a simple change that has a dramatic impact on the memory footprint.

In this lecture I would like to thank you for finishing the course and offer some final words.

Traffic lights

Read about what's good
what should give you pause
and possible dealbreakers
Explores garbage collection in .NET, which is essential for writing efficient and performant C# applications, especially in memory-intensive scenarios
Covers memory allocation problems like boxing, string duplication, and collection resizing, which are common pitfalls in C# development that can lead to performance bottlenecks
Discusses the Dispose pattern, which is an efficient design pattern in .NET for quickly releasing scarce operating system resources when they are no longer needed
Examines structs versus classes, which is a fundamental concept in C# that impacts memory usage and performance, especially when dealing with large amounts of data
Teaches how to measure the memory footprint of code, which is a valuable skill for identifying and resolving memory-related performance issues in C# applications
Requires learners to understand the fundamentals of the .NET Framework, which may necessitate additional learning for those new to the platform

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Reviews summary

Mastering c# memory & garbage collection

According to learners, this course provides a clear and practical guide to C# memory management and the Garbage Collector. Students particularly praise the easy-to-follow explanations of complex topics like the GC process, stack vs heap, and value/reference types. Many found the practical tricks and tips for optimizing memory usage in real-world scenarios highly valuable, highlighting insights into issues like boxing overhead, string concatenation, structs vs classes, and List resizing. Reviewers feel it significantly improved their understanding and ability to write more efficient code.
Well-suited for beginner to intermediate devs.
"Perfect for beginner or intermediate C# developers looking to level up their skills."
"As an intermediate developer, I found the content challenging yet accessible."
"Provides a solid foundation for job interviews on C# memory topics."
"It assumes some basic C# knowledge, but the GC concepts are explained from scratch."
Instructor is knowledgeable and engaging.
"The instructor is clearly knowledgeable and passionate about the topic."
"His delivery style is engaging and makes the lectures easy to follow."
"He explains complex ideas patiently and effectively with diagrams and code."
"I appreciated the instructor's practical approach and real-world examples."
Deepens knowledge of .NET memory handling.
"Significantly improved my understanding of .NET memory management overall."
"Provided an excellent foundation for understanding garbage collection internals."
"I now feel much more confident about managing memory in my C# projects."
"This course is a must for any C# developer wanting to write more efficient code."
Breaks down complex GC concepts effectively.
"The instructor explains the Garbage Collector in .NET clearly and practically."
"He breaks down the Garbage Collection process into easy-to-understand concepts."
"Made complex topics like stack, heap, value and reference types very clear."
"Really helped solidify my understanding of how the GC works internally."
Offers valuable techniques for memory efficiency.
"I learned several quick and easy strategies to resolve memory allocation problems."
"The tips on boxing, strings, and collections are incredibly practical for daily coding."
"Helped me identify and fix performance bottlenecks in my own C# applications."
"Discovering the memory footprint of List resizing and LINQ was eye-opening and useful."

Activities

Be better prepared before your course. Deepen your understanding during and after it. Supplement your coursework and achieve mastery of the topics covered in C# Memory Tricks: Learn How To Master The Garbage Collector with these activities:
Review .NET Fundamentals
Solidify your understanding of .NET fundamentals to better grasp the concepts of memory management and garbage collection.
Browse courses on .Net Framework
Show steps
  • Review the basics of the .NET Framework architecture.
  • Study the differences between value types and reference types.
  • Practice writing simple C# programs to reinforce your understanding.
Read 'CLR via C#' by Jeffrey Richter'
Gain a deeper understanding of the CLR and garbage collection by studying a comprehensive resource.
Show steps
  • Obtain a copy of 'CLR via C#' by Jeffrey Richter.
  • Read the chapters related to memory management and garbage collection.
  • Take notes on key concepts and examples.
Read 'Pro .NET Memory Management: For Better Code, Performance, and Scalability'
Deepen your understanding of .NET memory management with a book focused on performance and scalability.
Show steps
  • Obtain a copy of 'Pro .NET Memory Management' by Konrad Kokosa.
  • Read the chapters related to performance optimization and scalability.
  • Experiment with the code examples provided in the book.
Four other activities
Expand to see all activities and additional details
Show all seven activities
Implement Dispose Pattern
Reinforce your understanding of resource management by implementing the Dispose pattern in various scenarios.
Show steps
  • Create a class that uses unmanaged resources.
  • Implement the IDisposable interface.
  • Write a Dispose method to release the unmanaged resources.
  • Test the implementation to ensure resources are properly released.
Write a blog post on C# memory management
Solidify your understanding of C# memory management by explaining the concepts in your own words.
Show steps
  • Choose a specific topic related to C# memory management.
  • Research the topic and gather relevant information.
  • Write a clear and concise blog post explaining the concept.
  • Include code examples and diagrams to illustrate the concept.
  • Publish the blog post on a platform like Medium or your personal website.
Create a cheat sheet for C# memory management
Improve retention by creating a concise cheat sheet summarizing key concepts and best practices for C# memory management.
Show steps
  • Review the course materials and identify key concepts.
  • Summarize each concept in a concise and easy-to-understand manner.
  • Organize the cheat sheet into logical sections.
  • Include code examples and diagrams to illustrate the concepts.
Build a memory profiler tool
Apply your knowledge of memory management by building a tool that can analyze the memory usage of C# applications.
Show steps
  • Design the architecture of the memory profiler tool.
  • Implement the core functionality to collect memory usage data.
  • Develop a user interface to visualize the memory usage data.
  • Test the tool with different C# applications.

Career center

Learners who complete C# Memory Tricks: Learn How To Master The Garbage Collector will develop knowledge and skills that may be useful to these careers:
Performance Engineer
A Performance Engineer is responsible for optimizing the performance of software systems. This course is directly relevant to a Performance Engineer because it addresses memory management in C#. The course helps understand how to identify and resolve memory-related performance bottlenecks. By mastering .NET memory optimization and learning to measure the memory footprint of code, a Performance Engineer can improve the efficiency of applications. A firm grasp of these concepts helps maintain high-performing systems.
C# Developer
A C# Developer focuses on building applications and software solutions using the C# programming language. This course directly aids a C# Developer by teaching memory optimization techniques. The course helps improve the performance and stability of their applications. By learning how to avoid common memory allocation problems such as unexpected boxing and string duplication, a C# Developer can write more efficient code. This course will be useful to brush up on skills, especially due to the course objective about mastering .NET memory optimization.
Software Developer
A Software Developer crafts code and designs systems to meet specific needs. This course on C# memory management helps a Software Developer write efficient code with a smaller memory footprint. Understanding garbage collection, as taught in the course, helps prevent performance bottlenecks and unexpected OutOfMemory exceptions. By learning the secrets of garbage collection in .NET, the Software Developer can produce robust and scalable applications. Specifically, the course helps the developer master .NET memory optimization and discover the truth about finalizers.
Application Developer
An Application Developer designs and builds software applications for computers and mobile devices. This course helps an Application Developer write memory-efficient C# code. Understanding garbage collection and memory management practices, as taught in the course, enables the developer to create applications that perform well and consume fewer resources. This is especially essential for mobile applications with limited memory. Application developers will benefit from the course objective about learning the unexpected memory footprint of List resizing.
Technical Lead
A Technical Lead guides a team of developers, ensuring code quality and efficient development practices. This course helps the Technical Lead guide their team in writing efficient C# code with optimal memory management. The course knowledge assists the Technical Lead in mentoring junior developers and enforcing best practices related to memory usage. The course will be helpful to the Technical Lead because the team will learn how to measure the memory footprint of code. Also, the team will be able to write code that does not burn through memory.
Game Developer
A Game Developer creates video games, often working with resource-intensive processes. This course provides Game Developers with knowledge of C# memory management that is critical for optimizing game performance. Efficient memory usage, as taught in this course, can enhance the fluidity and stability of games, reducing crashes and improving frame rates. The strategies to resolve memory allocation problems, which are taught in this course, leads to smoother gaming experiences. It will be useful for Game Developers as the course teaches how to measure the memory footprint of your code.
Software Consultant
A Software Consultant advises clients on software development strategies and best practices. This course provides a Software Consultant with expertise in C# memory management that they can leverage in their recommendations. The course helps ensure that client projects are built with efficient and scalable code. The consultant will be able to offer solutions related to garbage collection issues by understanding the truth about finalizers. The course on C# Memory Tricks adds significant value to the consultant's toolkit.
Financial Software Developer
A Financial Software Developer develops software for financial institutions, where performance and accuracy are paramount. This course helps a Financial Software Developer by providing knowledge of C# memory management, which is essential for optimizing the performance of financial applications. By reducing memory consumption and improving code efficiency, the developer can enhance the reliability and speed of critical systems. The course may be useful due to the course objective on how to measure the memory footprint of your code.
Systems Architect
A Systems Architect designs the structure of computer systems, ensuring they meet performance and scalability requirements. This course provides Systems Architects with in-depth knowledge of C# memory management. This knowledge supports the architect in making informed decisions about system design and resource allocation. Understanding how the garbage collector works and how to optimize memory usage, allows the Systems Architect to design systems that are efficient and scalable. In particular, this course will be helpful as it teaches what assumptions the garbage collector makes about object size and lifetime.
Embedded Systems Engineer
An Embedded Systems Engineer develops software for embedded devices. This course may be useful to an Embedded Systems Engineer, because memory management is critical in embedded systems with limited resources. This constraint means that there is little memory available, and the engineer will need to be creative to ensure all applications and processes run appropriately. The course teaches how to master .NET memory optimization. The course may be useful to improve the performance and stability of embedded systems code written in C#.
Database Programmer
A Database Programmer writes code to interact with databases. This course may be useful to a Database Programmer when writing C# code that interacts with databases. Efficient memory management can improve the performance of database operations and prevent memory leaks in long-running applications. The topics around manual deallocation with the Dispose pattern from this course may be useful to ensure that database resources are efficiently used and released. This helps the Database Programmer optimize database interactions and application performance.
Quantitative Analyst
A Quantitative Analyst develops mathematical models for financial analysis. This course may be useful as a Quantitative Analyst often uses programming languages like C# to implement these models. Memory management skills, as taught in the course, can help optimize the performance of computationally intensive financial simulations. The course may be useful, as it discusses how to use structs versus classes and which one is better for memory management.
Compiler Developer
A Compiler Developer works on the creation and optimization of compilers. This course may be useful to a Compiler Developer since it provides a deep understanding of memory management in .NET, which can be leveraged to improve compiler design. The course may be useful as it discusses assumptions the garbage collector makes about object size and lifetime. Also the course teaches how to master .NET memory optimization.
Operating Systems Developer
An Operating Systems Developer designs and implements operating systems, which are responsible for managing computer resources. The knowledge of memory management, taught in this course, may be useful to an Operating Systems Developer when working with C# code in the operating system's development. The tips and tricks in this course on how to measure the memory footprint of your code may be useful to optimize resource usage in operating systems components. This enables them to create stable and robust operating system functions.
Robotics Software Engineer
A Robotics Software Engineer develops software for robots and autonomous systems. This course may be useful to a Robotics Software Engineer, as memory management is crucial for robots. The course may be useful to them, because it discusses structs versus classes and which one is better, and includes tips on how to manually deallocate with the Dispose pattern. Efficient memory usage enhances real-time performance and reliability of robots.

Reading list

We've selected two books that we think will supplement your learning. Use these to develop background knowledge, enrich your coursework, and gain a deeper understanding of the topics covered in C# Memory Tricks: Learn How To Master The Garbage Collector.
Provides an in-depth look at the Common Language Runtime (CLR), which is essential for understanding how .NET manages memory. It covers topics such as garbage collection, object allocation, and the internal workings of the CLR. This book is commonly used as a reference by .NET developers. Reading this book will provide a deeper understanding of the concepts covered in the course.
Dives deep into .NET memory management, covering topics such as the garbage collector, memory allocation, and performance optimization. It provides practical advice and examples for improving the memory footprint of your C# code. This book is valuable as additional reading to expand on the course material and provide real-world insights.

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