The Backend Engineering Show with Hussein Nasser

Dive into the fascinating world of page faults! Discover how processes access memory, the costs involved, and the mechanics of virtual memory. Learn about different types of faults including first-access, stack expansion, and copy-on-write. Explore the implications of memory sharing in multi-process environments and the performance overheads of kernel operations. Get insights into lazy loading and how the kernel manages memory mapping, alongside protecting processes with permissions. It's a deep yet engaging look at how our systems handle memory!

On October 19 2025 AWS experienced an outage that lasted over a day, 10 days later we finally got the root cause analysis and we know exactly what caused the DNS to fail0:00 Summary 5:30 How did Dynamo lost its DNS?13:41 EC2 Errors 16:16 Network Load Balancer ErrorsRCA here https://aws.amazon.com/message/101925/

This discussion explores the importance of graceful shutdowns in backend connections. It highlights reasons for closing connections, like resource management and preventing overload. Listeners learn how HTTP/1.1 and HTTP/2 handle these shutdowns, particularly the unique GOAWAY frame in HTTP/2. The impact of client-side pooling, along with historic issues like browser bugs related to GOAWAY, is also examined. The conversation wraps up with a summary of best practices for managing shutdowns effectively.

Postgres 18 has been released with many exciting features such as UUIDv7, Over explain module, composite index skip scans, and the most anticipated asynchronous IO with worker and io_uring mode which I uncover in this show. Hope you enjoy it0:00 Intro1:30 Synchronous vs Asynchronous calls3:00 Synchronous IO6:30 Asynchronous IO10:00 Postgres 17 synchronous io 17:20 The challenge of Async IO in Postgres 1820:00 io_method worker23:00 io_method io_uring29:30 io_method sync 31:08 Async IO isn’t done! 31:30 Support for backend writers32:36 Improve worker io_method33:00 direct io support 37:00 Summary

Fundamentals of Operating Systems Course https://oscourse.winktls is brilliant.TLS encryption/decryption often happens in userland. While TCP lives in the kernel. With ktls, userland can hand the keys to the kernel and the kernel does crypto. When calling write, the kernel encrypts the packet and send it to the NIC.When calling read, the kernel decrypts the packet and handed it to the userspace. This mode still taxes the host’s CPU of course, so there is another mode where the kernel offloads the crypto to the NIC device! Host CPU becomes free. Incoming packets to the NIC are decrypted in device before they are DMAed to the kernel. outgoing packets are encrypted before they leave the NIC to the network.ktls still need handshake to happen in userspace. There is also enabling zerocopy in some cases (now that kernel has context) Deserves a video. So much good stuff.0:00 Intro2:00 Userspace SSL Libraries 3:00 ktls 6:00 Kernel Encrypts/Decrypts (TLS_SW)8:20 NIC offload mode (TLS_HW)10:15 NIC does it all (TLS_HW_RECORD)12:00 Write TX Example13:50 Read RX Example17:00 Zero copy (sendfile)https://docs.kernel.org/networking/tls-offload.html

If you are bored of contemporary topics of AI and need a breather, I invite you to join me to explore a mundane, fundamental and earthy topic.The CPU.A reading of my substack article https://hnasr.substack.com/p/the-beauty-of-the-cpu

This new PostgreSQL 17 feature is game changer. They know can combine IOs when performing sequential scan. Grab my database coursehttps://courses.husseinnasser.com

No technical video today, just talking about the idea of discipline and consistency.

Fundamentals of Operating Systems Course This video is an overview of how the operating system kernel does socket management and the different data structures it utilizes to achieve that.timestamps0:00 Intro1:38 Socket vs Connections7:50 SYN and Accept Queue18:56 Socket Sharding23:14 Receive and Send buffers27:00 Summary

Discover the fascinating world of long polling and its role in backend efficiency. Explore how it improves upon traditional polling, reducing latency and resource consumption. Delve into its benefits for scalable database management, emphasizing efficient data sorting and predictable system behavior. Learn about request resumption and how to harness the full potential of long polling to enhance your applications. This insightful discussion uncovers the genius behind a seemingly simple yet powerful design pattern.