Episode · The Backend Engineering Show with Hussein Nasser
When do you use threads?
13 Sep 2024 · 31 min
Episode notes
Fundamentals of Operating Systems Course https://os.husseinnasser.com When do you use threads? I would say in scenarios where the task is either 1) IO blocking task 2) CPU heavy 3) Large volume of small tasks In any of the cases above, it is favorable to offload the task to a thread. 1) IO blocking task When you read from or write to disk, depending on how you do it and the kernel interface you used, the write might be blocking. This means the process that executes the IO will not be allowed to execute any more code until the write/read completes. That is why you see most logging operations…
Podcast
The Backend Engineering Show with Hussein Nasser
Hussein Nasser · Tech & Science · English
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. Most of my content in the p
More from The Backend Engineering Show with Hussein Nasser All episodes →
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1 Nov 2024 · 39 min
Six stages of a good software engineer
You get better as a software engineer when you go through these stages. 0:00 Intro 1:15 Understand a technology 7:07 Articulate how it works 15:30 Understand its’ limitations 19:48 Try to build something better 27:45 Realize what you built also has limitations 32:48 Appreciate the original tech as is Understand a technology We use technologies all the time without knowing how it works. And it is ok not knowing how things work if interests isn’t there. But when there is interest to understand how something works, pursue it. It feels good when you understand how something works because you…
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25 Oct 2024 · 18 min
This new Linux patch can speed up Reading Requests
Fundamentals of Operating Systems Course https://oscourse.win Very clever! We often call read/rcv system call to read requests from a connection, this copies data from kernel receive buffer to user space which has a cost. This new patch changes this to allow zero copy with notification. “Reading' data out of a socket instead becomes a “notification” mechanism, where the kernel tells userspace where the data is.” This kernel patch enables zero copy from the receive queue. https://lore.kernel.org/io-uring/ZwW7_cRr_UpbEC-X@LQ3V64L9R2/T/ 0:00 Intro 1:30 patch summary 7:00 Normal Connection Read…
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18 Oct 2024 · 1 hr 2 min
Cloudflare's 150ms global cache purge | Deep Dive
Cloudflare built a global cache purge system that runs under 150 ms. This is how they did it. Using RockDB to maintain local CDN cache, and a peer-to-peer data center distributed system and clever engineering, they went from 1.5 second purge, down to 150 ms. However, this isn’t full picture, because that 150 ms is just actually the P50. In this video I explore Clouldflare CDN work, how the old core-based centralized quicksilver, lazy purge work compared to the new coreless, decentralized active purge. In it I explore the pros and cons of both systems and give you my thoughts of this system.…
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28 Sep 2024 · 29 min
MySQL is having a bumpy journey
Fundamentals of Database Engineering udemy course https://databases.win MySQL has been having bumpy journey since 2018 with the release of the version 8.0. Critical crashes that made to the final product, significant performance regressions, and tons of stability and bugs issues. In this video I explore what happened to MySql, are these issues getting fixed? And what is the current state of MySQL at the end of 2024. 0:00 Intro 2:00 MySQL 8.0 vs 5.7 Performance 11:00 Critical Crash in 8.0.38, 8.4.1 and 9.0.0 15:40 Is 8.4 better than 8.0.36? 16:30 More Features = More Bugs 22:30 Summary and my…
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20 Sep 2024 · 21 min
How many kernel calls in NodeJS vs Bun vs Python vs native C
Fundamentals of Operating Systems Course https://oscourse.win In this video I use strace a performance tool that measures how many system calls does a process makes. We compare a simple task of reading from a file, and we run the program in different runtimes, namely nodejs, buns , python and native C. We discuss the cost of kernel mode switches, system calls and pe 0:00 Intro 5:00 Code Explanation 6:30 Python 9:30 NodeJS 12:30 BunJS 13:12 C 16:00 Summary
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7 Sep 2024 · 25 min
Frontend and Backends Timeouts
I am fascinated by how timeouts affect backend and frontend programming. When a party is waiting on something you can place a timeout to break the wait. This is useful for freeing resources to more critical processes, detecting slow operations and even avoiding DOS attacks. Contrary to common beliefs, timeouts are not exclusive to request processing, they can be applied to other parts of the frontend-backend communications. Let us explore this briefly. 0:00 Intro 2:30 Connection Timeout 5:00 Request Read timeout 10:00 Wait Timeout 12:00 Usage Timeout 14:00 Response Timeout 16:00 Canceling a…
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2 Sep 2024 · 28 min
Postgres is combining IO in version 17
Learn more about database and OS internals, check out my courses Fundamentals of database engineering https://databases.win Fundamentals of operating systems https://oscourse.win This new PostgreSQL 17 feature is game changer. You see, postgres like most databases work with fixed size pages. Pretty much everything is in this format, indexes, table data, etc. Those pages are 8K in size, each page will have the rows, or index tuples and a fixed header. The pages are just bytes in files and they are read and cached in the buffer pool. To read page 0, for example, you would call read on offset 0…
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30 Aug 2024 · 37 min
Windows vs Linux Kernel
Fundamentals of Operating Systems Course https://os.husseinnasser.com Why Windows Kernel connects slower than Linux I explore the behavior of TCP/IP stack in Windows kernel when it receives a RST from the backend server especially when the host is available but the port we are trying to connect to is not. This behavior is exacerbated by having both IPv6 and IPv4 and if the happy eye ball protocol is in place where IPv6 is favorable. 0:00 Intro 0:30 Fundamentals TCP/IP 3:00 Unreachable Port Behavior 6:00 Client Kernel Behavior (Linux vs Windows) 11:40 Slow TCP Connect on Windows 15:00…
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25 Aug 2024 · 20 min
Running out of TCP ephemeral source ports
In this episode of the backend engineering show I describe an interesting bug I ran into where the web server ran out of ephemeral ports causing the system to halt. 0:00 Intro 0:30 System architecture 2:20 The behavior of the bug 4:00 Backend Troubleshooting 7:00 The cause 15:30 Ephemeral ports on loopback
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20 May 2024 · 17 min
io uring gets even faster
Fundamentals of Operating Systems Course https://os.husseinnasser.com Linux I/O expert and subsystem maintainer Jens Axboe has submitted all of the IO_uring feature updates ahead of the imminent Linux 6.10 merge window. In this video I explore this with a focus on what zerocopy. 0:00 Intro 0:30 IO_uring gets faster 2:00 What is io_uring 7:00 How Normal Copying Work 12:00 How Zero Copy Works 13:50 ZeroCopy and TLS https://www.phoronix.com/news/Linux-6.10-IO_uring https://lore.kernel.org/io-uring/[email protected]/?s=09
