In this episode of the backend engineering show I go through the main job of the network interface controller (NIC for short) and how the datacenter is pushing it to the limit by allowing it to do more TCP/IP processing, creating what is being popularized as smartNIC. 0:00 Intro 1:20 What is a NIC? 3:40 NIC job 8:00 When does the OS get involved 12:40 Promiscuous mode 14:00 SmartNIC 18:30 Disadvantages Resources https://developer.nvidia.com/networking/ethernet-adapters https://www.theregister.com/2022/08/11/smartnics_network_market/ https://arxiv.org/abs/1803.09615 Fundamentals of Networking for Effective Backends udemy course (link redirects to udemy with coupon) https://network.husseinnasser.com --- Support this podcast: https://anchor.fm/hnasr/support

In this episode of the backend engineering show I discuss consistent hashing a very important algorithm in distributed computing specially in database systems such as Apache Cassandra and DynamoDB. 0:00 Intro 2:00 Problem of Distributed Systems 5:00 When to Distribute 7:00 Simple Hashing 9:30 Where Simple Hashing Breaks 11:40 Consistent Hashing 18:00 Adding a Server 21:15 Removing a Server 22:30 Limitations --- Support this podcast: https://anchor.fm/hnasr/support

In this episode of the backend engineering show I go through and discuss the Homa Protocol paper which attempts to replace TCP as a protocol in the data centers. I learned a lot from this paper, I have my criticisms of certain aspects, timestamps for topics discussed below. It appears there is a path to replace TCP in the datacenter and professor John tries to explain this path. Referenced materials mentioned in the episode Overview paper https://web.stanford.edu/~ouster/cgi-bin/papers/replaceTcp.pdf Homa 2018 paper (Details) https://people.csail.mit.edu/alizadeh/papers/homa-sigcomm18.pdf NIC Offloading in Linux https://en.wikipedia.org/wiki/TCP_offload_engine#Support_in_Linux Curl disabling Nigel Algo https://github.com/curl/curl/commit/4732ca5724072f132876f520c8f02c7c5b654d9 0:00 Intro 3:00 The nature of networking data center 5:30 TCP Segments 7:30 There is no “Request” in TCP 12:00 What so unique about Data centers? 14:00 Message Throughput vs Data throughput 18:25 Congestion Control 22:38 Homa’s Congestion Control 25:00 Server Core Load Balancing 28:30 NIC offloading 30:00 Everything Wrong about TCP 37:00 Why not QUIC? 40:00 Limitation of Streaming 44:10 Load Balancing Stream Reading 47:15 Can we treat Segments as Messages? 51:00 Dispatching Messages is Easier 53:00 Connection Orientation 1:00:00 Sender Driven Congestion Control 1:03:00 In Order Packet Delivery 1:07:00 DCTCP 1:08:30 Homa is Message Based 1:11:00 Home is Connection Less 1:12:00 Receiver Driven Congestion Control 1:15:19 Out of Order Packets 1:16:20 Homa API is not Compatible with TCP 1:17:40 Will Homa come to HTTP? 1:18:45 Conclusion --- Support this podcast: https://anchor.fm/hnasr/support

ByteDance, the company behind TikTok is proposing few patches to the linux kernel to make kernel reboots via kexec go from 500ms down to 15 ms saving huge time in updating kernel on thousands of machines. Let us discuss this 0:00 Intro 1:30 Linux Kernel Reboot Options 2:30 how kexec works 4:00 The optimization 5:00 Going through the patch 6:00 Updating Servers at TikTok scale 9:00 Summary https://www.phoronix.com/news/Bytedance-Faster-Kexec-Reboot https://lore.kernel.org/lkml/20220725083904.56552-1-huangjie.albert@bytedance.com/ --- Support this podcast: https://anchor.fm/hnasr/support

We discuss the CVE-2022-2274 OpenSSL Vulnerability. The OpenSSL 3.0.4 release introduced a serious bug in the RSA implementation for X86_64 CPUs supporting the AVX512IFMA instructions. This issue makes the RSA implementation with 2048 bit private keys incorrect on such machines and memory corruption will happen during the computation. As a consequence of the memory corruption an attacker may be able to trigger a remote code execution on the machine performing the computation. 0:00 Intro 1:00 CVE-2022-2274 3:00 AVX512IFMA CISC 5:00 How the bug works 7:10 How can it be triggered Resources https://www.openssl.org/news/secadv/20220705.txt https://github.com/openssl/openssl/issues/18625 https://guidovranken.com/2022/06/27/notes-on-openssl-remote-memory-corruption/ https://eprint.iacr.org/2018/335 https://github.com/openssl/openssl/commit/4d8a88c134df634ba610ff8db1eb8478ac5fd345 https://linux.die.net/man/3/bn_internal https://www.microfocus.com/documentation/enterprise-developer/ed60/ES-WIN/GUID-E3960B1E-C42E-4748-A5EB-6E12507C9CD7.html https://www.microcontrollertips.com/risc-vs-cisc-architectures-one-better/ Fundamentals of Networking for Effective Backends udemy course (link redirects to udemy with coupon) https://network.husseinnasser.com --- Support this podcast: https://anchor.fm/hnasr/support

Postgres 15 introduces a new syntax to treat nulls as not distinct. This will allow developers to create a unique constraint on nullable fields and have inserts with nulls fail instead of having it allowed based on today's standard. Fundamentals of Networking for Effective Backends udemy course (link redirects to udemy with coupon) https://network.husseinnasser.com Fundamentals of Database Engineering udemy course (link redirects to udemy with coupon) https://database.husseinnasser.com https://blog.rustprooflabs.com/2022/07/postgres-15-unique-improvement-with-null https://www.postgresql.org/message-id/flat/84e5ee1b-387e-9a54-c326-9082674bde78%40enterprisedb.com --- Support this podcast: https://anchor.fm/hnasr/support

memchr() is a function that searches in a memory block for a character, this has been recently improved in the latest linux patch and we can learn something from this improvement I think, lets discuss. https://www.phoronix.com/scan.php?page=news_item&px=Linux-Kernel-Faster-memchr Fundamentals of Networking for Effective Backends udemy course (link redirects to udemy with coupon) https://network.husseinnasser.com --- Support this podcast: https://anchor.fm/hnasr/support

Amazon Aurora PostgreSQL-Compatible Edition now supports PostgreSQL major version 14 (14.3). Let us discuss this news. https://aws.amazon.com/about-aws/whats-new/2022/06/amazon-aurora-supports-postgresql-14/ 0:00 Intro 1:00 Database on the Cloud options 3:45 Amazon Aurora supports Postgres 14 6:00 Postgres 14 vs Postgres 13 --- Support this podcast: https://anchor.fm/hnasr/support

Rogers Communications, the Canadian ISP is down. One of its ASNs (they have many) is AS812 with over 5 million IP addresses. Tried a few and none of them can be pinged from the US (not sure if ICMP is disabled or not) This is a huge deal for all Canadians and businesses affected. So sorry for every one who is affected by this, and kudus to all the engineers at Rogers working to fix this for the past what? 11 hours now? If an ASN goes dark like a Facebook or a Cloudflare that isn't a big deal you can go without using Facebook for a day. But if this is your ISP's ASN that connects you to the rest of the World goes down, actual users won't be able to connect. We still don't know the cause but my guess it might be a bad BGP entry? that's what happened to Cloudflare or FB, could be something different. again so sorry for all my Canadian followers affected. Will make a video when I get a chance Resources https://www.bigdatacloud.com/asn-lookup/AS812 https://www.bigdatacloud.com/asn-lookup/AS7018 --- Support this podcast: https://anchor.fm/hnasr/support

In this episode of the backend engineering show I’ll discuss Fill Factor index property, an important key parameter for a good performing database. I will also discuss how it is a double edge sword and can break or Make your db. Chapters 0:00 Intro 1:48 Start of the Show 4:30 Database Storage Representation 6:30 IO Cost 10:00 Index Page 13:30 Page Splits Cost 18:00 Indexing UUIDs 19:45 FillFactor 23:15 Bad FillFactor values 26:40 Fragmentation In Indexes 30:30 Summary Fundamentals of Networking for Effective Backends udemy course (link redirects to udemy with coupon) https://network.husseinnasser.com Fundamentals of Database Engineering udemy course (link redirects to udemy with coupon) https://database.husseinnasser.com --- Support this podcast: https://anchor.fm/hnasr/support

In this video I discuss early hints HTTP 103 status code, the problem it solves and the challenges it has. --- Support this podcast: https://anchor.fm/hnasr/support

YugabyteDB is a postgres compatible and cloud native database. Read committed isolation level is a critical feature and adding it might lure more postgres customer’s to move to the cloud native database. But will they compete in front of Google’s new AlloyDB ?    0:00 Yogabyte implements Read committed 4:20 Isolation Levels 8:40 Can YugabyteDB compete with Google AlloyDB?   https://www.theregister.com/2022/06/28/yugabytedb_215/ https://docs.yugabyte.com/preview/architecture/transactions/explicit-locking/ --- Support this podcast: https://anchor.fm/hnasr/support

Fundamentals of Networking for Effective Backends udemy course (link redirects to udemy with coupon) https://network.husseinnasser.com Transport Layer security or TLS is a protocol that encrypted the communication between client and server. TLS can also be used to authenticate the server, when the client also requires authentication this is called Mutual TLS and this is the topic of today’s show. 0:00 Introduction 2:00 What is TLS? 7:00 Server Authentication TLS 14:00 Advantages of one way TLS 19:44 Disadvantages of one way TLS 29:00 mTLS 31:00 Advantages of MTLS 37:00 The Problems of mTLS 43:00 Summary and my Thoughts --- Support this podcast: https://anchor.fm/hnasr/support

In this episode we go through the cloud flare outage blog.  https://blog.cloudflare.com/cloudflare-outage-on-june-21-2022/ Fundamentals of Networking for Effective Backends udemy course (link redirects to udemy with coupon) https://network.husseinnasser.com --- Support this podcast: https://anchor.fm/hnasr/support

In this episode of the backend engineering show I go through the Extensible Prioritization Scheme for HTTP. This RFC addresses the problem in HTTP where the client prefers certain requests to be served before others. This RFC was designed by Lucas Pardue from Cloudflare and Kazoo Oku from Fastly.   0:00 The Request Priority Problem  13:00 How RFC 9218 addresses the problem 25:00 HTTP/1.x Backends 32:00 Summary  RFC 9218 https://datatracker.ietf.org/doc/rfc9218/ --- Support this podcast: https://anchor.fm/hnasr/support

In this video I explain what is a zero day vulnerability or attack.   Fundamentals of Networking for Effective Backends udemy course (link redirects to udemy with coupon) https://network.husseinnasser.com --- Support this podcast: https://anchor.fm/hnasr/support

IPv4 UniCast Extensions Project attempts to unreserve old IPv4 subnets so they are publicly addressable. Is it worth it? Let us discuss  https://blog.apnic.net/2022/05/31/cutting-down-on-ip-address-waste/Unicast Use of the Formerly Reserved 127/8 https://datatracker.ietf.org/doc/draft-schoen-intarea-unicast-127/ Unicast Use of the Lowest Address in an IPv4 Subnet https://datatracker.ietf.org/doc/draft-schoen-intarea-unicast-lowest-address/   Unicast Use of the Formerly Reserved 240/4 https://datatracker.ietf.org/doc/draft-schoen-intarea-unicast-240/   Unicast Use of the Formerly Reserved 0/8 https://datatracker.ietf.org/doc/draft-schoen-intarea-unicast-0/ https://twitter.com/TheRealRevK/status/1532033651650830339   Fundamentals of Networking for Effective Backends udemy course (link redirects to udemy with coupon) https://network.husseinnasser.com --- Support this podcast: https://anchor.fm/hnasr/support

Fantastic gains in Postgres 15! improved sorting by 371%. Normally you can avoid sorting by using an index access path. However, you can’t always have an index on every group by, order by, join or distinct predict. This will come handy. Let us discuss Resources https://www.phoronix.com/scan.php?page=news_item&px=PostgreSQL-15-Faster-Sort https://techcommunity.microsoft.com/t5/azure-database-for-postgresql/speeding-up-sort-performance-in-postgres-15/ba-p/3396953#change3 https://www.postgresql.org/docs/15/release-15.html#id-1.11.6.5.4 https://techcommunity.microsoft.com/t5/sql-server-blog/understanding-sql-server-fast-forward-server-cursors/ba-p/383556 --- Support this podcast: https://anchor.fm/hnasr/support

In this episode of the backend engineering show I discuss UDP hole punching in details.  Fundamentals of Networking for Effective Backends udemy course (link redirects to udemy with coupon) https://network.husseinnasser.com --- Support this podcast: https://anchor.fm/hnasr/support

As a new parent, you get exposed to a whole new world. There is this new toddler song “Five little monkeys jumping on the bed” where it starts with five monkeys jumping on the bed and one falls off the bed and the mom calls the doctor and then another monkey falls and the mom calls the doctor again. This keeps going until all monkeys are no longer on the bed. This clearly looks like a software engineering problem. In the face of it is extreme inefficiency in IO with the mom calling the doctor 5 times in span of 3 minutes. The mom could decide to wait for all monkeys to fall and call the doctor once. A Method that is known as batching. Two problems with this approach; the first is latency the mom can’t wait, she is worried, she needs immediate answer from the doctor for the first monkey that fell. The second problem is we don’t know if more monkeys are going to fall off the bed, so while the mom waiting, the first monkey will be in pain and will “starve”. We makes decisions like this constantly in software engineering. In some database systems for example commits from transactions are grouped and batched for few microseconds/milliseconds so more commits can arrive and the database can flush/fsync the WAL once. This is specially important in highly concurrent system because disk fsync is costly and bypasses the operating system cache. However, this comes at a cost of slight delay in transaction commits but less IO in general. To batch or not to batch. The five little monkey problem doesn’t have one right solution it all depends. --- Support this podcast: https://anchor.fm/hnasr/support