The Backend Engineering Show with Hussein Nasser

By Hussein NasserTechnology

The Backend Engineering Show with Hussein Nasser episodes

February 18, 2024 The Danger of Defaults - A PostgreSQL Story
I talk about default values and how PostgreSQL 14 got slower when a default parameter has changed.
Mike's blog
https://smalldatum.blogspot.com/2024/02/it-wasnt-performance-regression-in.html

12 min
February 16, 2024 Database Background writing
Background writing is a process that writes dirty pages in shared buffer to the disk (well goes to the OS file cache then get flushed to disk by the OS) I go into this process in this video
10 min
January 29, 2024 The Cost of Memory Fragmentation
Fragmentation is a very interesting topic to me, especially when it comes to memory.
While virtually memory does solve external fragmentation (you can still allocate logically contiguous memory in non-contiguous physical memory) it does however introduce performance delays as we jump all over the physical memory to read what appears to us for example as contiguous array in virtual memory.
You see, DDR RAM consists of banks, rows and columns. Each row has around 1024 columns and each column has 64 bits which makes a row around 8kib. The cost of accessing the RAM is the cost of “opening” a row and all its columns (around 50-100 ns) once the row is opened all the columns are opened and the 8 kib is cached in the row buffer in the RAM.
The CPU can ask for an address and transfer 64 bytes at a time (called bursts) so if the CPU (or the MMU to be exact) asks for the next 64 bytes next to it, it comes at no cost because the entire row is cached in the RAM. However if the CPU sends a different address in a different row the old row must be closed and a new row should be opened taking an additional 50 ns hit. So spatial access of bytes ensures efficiency,
So fragmentation does hurt performance if the data you are accessing are not contiguous in physical memory (of course it doesn’t matter if it is contiguous in virtual memory). This kind of remind me of the old days of HDD and how the disk needle physically travels across the disk to read one file which prompted the need of “defragmentation” , although RAM access (and SSD NAND for that matter) isn’t as bad.
Moreover, virtual memory introduces internal fragmentation because of the use of fixed-size blocks (called pages and often 4kib in size), and those are mapped to frames in physical memory.
So if you want to allocate a 32bit integer (4 bytes) you get a 4 kib worth of memory, leaving a whopping 4092 allocated for the process but unused, which cannot be used by the OS. These little pockets of memory can add up as many processes. Another reason developers should take care when allocating memory for efficiency.
40 min
December 13, 2023 The Real Hidden Cost of a Request
In this video I explore the hidden costs of sending a request from the frontend to the backend

Heard

https://medium.com/@hnasr/the-journey-of-a-request-to-the-backend-c3de704de223

14 min
October 28, 2023 Why create Index blocks writes
Fundamentals of Database Engineering udemy course (link redirects to udemy with coupon)
https://database.husseinnasser.com
Why create Index blocks writes
In this video I explore how create index, why does it block writes and how create index concurrently work and allow writes.
0:00 Intro
1:28 How Create Index works
4:45 Create Index blocking Writes
5:00 Create Index Concurrently

14 min
October 05, 2023 The Problems of an HTTP/3 Backend
HTTP/3 is getting popular in the cloud scene but before you migrate to HTTP/3 consider its cost. I explore it here.
0:00 Intro HTTP/3 is getting popular
3:40 HTTP/1.1 Cost
5:18 HTTP/2 Cost
6:30 HTTP/3 Cost
https://blog.apnic.net/2023/09/25/why-http-3-is-eating-the-world/

14 min
September 29, 2023 Encrypted Client Hello - The Pros & Cons

The Encrypted Client Hello or ECH is a new RFC that encrypts the TLS client hello to hide sensitive information like the SNI. In this video I go through pros and cons of this new rfc.
0:00 Intro
2:00 SNI
4:00 Client Hello
8:40 Encrypted Client Hello
11:30 Inner Client Hello Encryption
18:00 Client-Facing Outer SNI
21:20 Decrypting Inner Client Hello
23:30 Disadvantages
26:00 Censorship vs Privacy ECH
https://blog.cloudflare.com/announcing-encrypted-client-hello/
https://chromestatus.com/feature/6196703843581952
34 min
August 01, 2023 The Journey of a Request to the Backend
From the frontend through the kernel to the backend process
When we send a request to a backend most of us focus on the processing aspect of the request which is really just the last step.
There is so much more happening before a request is ready to be processed, most of this step happens in the Kernel. I break this into 6 steps, each step can theoretically be executed by a dedicated thread or process. Pretty much all backends, web servers, proxies, frameworks and even databases have to do all these steps and they all do choose to do it differently.

Grab my backend performance course https://performance.husseinnasser.com

0:00 Intro
3:50 What is a Request?
10:14 Step 1 - Accept
21:30 Step 2 - Read
29:30 Step 3 - Decrypt
34:00 Step 4 - Parse
40:36 Step 5 - Decode
43:14 Step 6 - Process

Medium article
https://medium.com/@hnasr/the-journey-of-a-request-to-the-backend-c3de704de223

53 min
June 24, 2023 They Enabled Postgres Partitioning and their Backend fell apart
In a wonderful blog, Kyle explores the pains he faced managing a Postgres instance for a startup he works for and how enabling partitioning sigintfically created wait events causing the backend and subsequently NGINX to through 500 errors.
We discuss this in this video/podcast
https://www.kylehailey.com/post/postgres-partition-pains-lockmanager-waits
34 min
June 09, 2023 WebTransport - A Backend Game Changer
WebTransport is a cutting-edge protocol framework designed to support multiplexed and secure transport over HTTP/2 and HTTP/3. It brings together the best of web and transport technologies, providing an all-in-one solution for real-time, bidirectional communication on the web.
Watch full episode (subscribers only) https://spotifyanchor-web.app.link/e/cTSGkq5XuAb

16 min

About The Backend Engineering Show with Hussein Nasser

From the publisher's feed

Welcome to the Backend Engineering Show podcast with your host Hussein Nasser. If you like software engineering you’ve come to the right place. I discuss all sorts of software engineering technologies and news with specific focus on the backend. All opinions are my own.