These are posts I have written. A lot of them are for self amusement. Feel free to send me a message if you have thoughts or questions. They are written in the Gemini text/gemini format. Then rendered to HTML. The same content is avaliable on my Gemini capsule gemini://gemini.clehaxze.tw [What is gemini://?]. In fact I encourge you view them through a Gemini browser (like this one) for the best experience. An Atom feed is also avaliable.

Latest Posts

2022-08-10: GNUNet File Sharing Tutorial and an Alternative to IPFS

With Web3 on the headlines all the day. I want to shift my view onto more traditional technologies. Blockchain is a great. Really, especially for transactions. Once I had to wire some money to an overseas bank. It literally took a week from sending to confirmed receiving. The fees are high too. Wi...

2022-07-29: Some Boring Analysis on TLGS Index (and messing with CERN's ROOT analysis framework)

Lupa[1] provides constant basic statistics about the Gemini network. Stats like how many servers are online, number of virtual hosts, TLS distribution, etc.. It's a really cool project. It got me asking.. what kinds of information can I extract from TLGS' index? Furthermore, I want to provide some...

2022-07-22: Search Engine Dilemma Bias VS Accuracy

One problem with the 3 current major Gemini search engines (GUS, Kennedy and TLGS) is the accuracy of their results. Searching anything too specific and they fail. I saw a lot of people writing about this frustration. "Fine, I'll bring bigger guns out" I thought. After days of reading on arXiv ...

2022-07-17: Cyber attack over Gemini is now a thing

This morning I logged into the server hosting TLGS, my Gemini search engine, and updated a few things. Then I go through the logs to see if anything intresting happened. Ohh... There were attempts to SQL inject through the search query! Yup, Gemini is big enough for security to matter now! It is d...

2022-07-11: Mixtile Blade 3 (RK3588) OpenCL performance

Mixtile Blade 3[1] is an intresting dev board. It runs on a RK 3855 SoC, the successor of the RK3399. Which a whole lot of other boards uses. Including QuartzPro64[2], ITX-3588J[3] and Rock Pi 5[4]. The 16GB model Blade 3 is priced at $369, much more expensive then the Rock Pi 5 at 189$ and the ex...

2022-07-09: Handle large file upload with Drogon web framework

Sometimes, you just need to handle large file uploads in your web application. Let's say you are writing a web drive. Dealing witch chunked upload can be a pain in most web frameworks. Not in Drogon - not well-known since the maintainers doesn't advertise much - Drogon supports processing large re...

2022-07-06: The trouble with trantor's threading design

This is just something on my mind and I'm trying to figure out how to solve. Most web frameworks use a work-stealing thread pool to improve throughput. Maybe one of the threads is overburdened with 100 tasks in its queue. But all the other 15 threads are idle. Other threads should be able to take ...

2022-06-30: FBInfer reduced our product crash by 50%

Just want to share how powerful this tool is. Infer[1], or FBInfer (since it's written by Facebook), is a static analyzer that can detect cross-function logic errors and potential data race in C, C++ and Objective-C. Which is just amazing. The company I work for runs on a C++ heavy product. Unfor...

2022-06-28: Coverage testing with CMake and GCov

This took me 3 days of on and off work to figure out. So I decide to write it down in case I need it again. And I want this to be more widely known. CMake is the most popular build system (generator) for C++. While test coverage is an important tool to find where bugs can hide. Testing usually tr...

2022-06-23: Understanding explicit OpenCL memory migration between devices

Lately someone emailed me asking how OpenCL memory migration works. To be specific, when and how to use the `clEnqueueMigrateMemObjects` API when using more then one device. Yeah, the description of it in Khronos's documentation[1] is very unhelpful. Nor is this API used often. I also spent quite...

2022-06-17: Upgrading WiFi bandwidth, hardware codec for VR Expreience

I'm a heavy VRChat player. My setup wasn't really good for VR per se. I had a relatively weak PC and limited LAN bandwidth. The upgrade is a bit costly, but I'm happy with the money spent. Also some unexpected issues caused my the upgrade. My setup is weird. Most people have their PC and playsp...

2022-06-14: RE: RE: The useful part of cryprocurrency

I feel I ought to explain my position. I think I understand and respect idiomdrottning's view. I just feel misinterpreted. And I'll try my best not to strawman him. If I do, by all means, it's my fault. My fault. I should have make it clear in my post. I mean "secure" by cryptographically secure...

2022-06-13: The useful part of cryptocurrency

Amid the current crypto price drop. I want to write about what cryptocurrency is actually useful for. And what I believe Crypto should be used for. Non of those NFT and ICO bulls*it. Or you can think this as my DD for investing in crypto. Or confirming my confirmation bias if you read WSB. At the...

2022-06-11: Unexpected complexity writing an async Spartan protocol server

Spartan[1] is a cool smol internet protocol. It's even simpler than Gemini. There's no TLS, no need for URL parsing and even less status codes! I just wrote my own Spartan client and server - Spartoi[2] in an afternoon, for fun. What I'm not expecting is some parts of it being (slightly) more comp...

2022-06-06: The stupid socket file descriptor leak in Dremini

TLGS'[1] crawler has had a crashing issue from the very beginning. The crawler tries to open too many sockets at the same time with the error message "sockets::createNonblockingOrDie: too many open sockets". The crawl dispatcher already limited how many concurrent craws can happen at any time. Fir...

2022-05-28: I can't stand developer interviews with algorithms (Or, why I'm learning APL)

I've been contacted by several HR people who are looking for a software engineer. It's good. I'm always looking for new challenges. What I can't stand is a large portion of the company decides that they should test the candidate's algorithm skill. Sorry, what? You just said you want to hire a seni...

2022-05-15: PSA: Potential libstdc++ hang in std::filesystem::symlink_status

Something I caught while running TLGS's crawler. Due to how drogon works. It needs to always successfully open a new socket on TCP connection. Otherwise the entire process is killed. But Gemini does not support multiple requests on the same connection. So it's easy to endup with a lot of open sock...

2022-05-13: Sane YouTube FPS on FireFox on OpenBSD

One thing I really want to be able to do is to load YouTube and put it in background as my work music. On OpenBSD the playback performance is a meh. Espically on Chromium. Opening a 720p 60FPS YouTube video yeilds ~10% frame drop in YouTube stats. Beyond that, the actual rendering rate feels more ...

2022-05-12: First time installing OpenBSD and stuff I did

I have been wanting to use OpenBSD for a while after hearing everyone prazing it's superior security. Until then, my only exposure to OpenBSD was installing it on a VM and maintaining Drogon on it. Needless to say, VM performance sucks. Not even Linux can do video playback on a VM without graphics...

2022-05-03: Two cents on the mistery of double slashes in URLs

I never expected my initial post about gemini crawlers would trun into a long conversation between crawler developers and server developers. Just saw Sean Conner's post[1] through cosmos about double slashes in URLs. This is just my 2 cents on the matter. RFC3986 section 3.3[2] contains the ABN...

2022-04-30: Securing web applications beyond just containers

This website, `clehaxze.tw` (or `gemini.clehaxze.tw` for Gemini) run on basically the same architecture as any modern web applications. A backend that that serves some files, talks to some database, read some files and render templates. It's my passion to make what I made absolutely secure. A back...

2022-04-22: RE: My common Gemini crawler pitfalls

I opened Cosmos today and saw a reply to my previous post about gemini crawler pitfalls[1]. In it (I assume) he complains a crawler sending requests to `gemini://gemini.conman.org/boston/2008/04/30/2008/04/30.1` which is non-existent. Yeah... that's my crawler. I shall fix it. Upon investigatio...

2022-04-20: My 3 weeks with the SlimeVR open source full-body tracker

SilmeVR is an IMU-only open source full body tracker (open firmware + software) for VR. For the non-initiated, normal VR only tracks your head and hands. While full body tracking in addition tracks waist, chest, ankles, and etc.. With FBT you can sit in VR and see your avatar also sitting down, wi...

2022-04-15: My half of year on Gemini

If you are browsing from HTTP. You really should get youself a Gemini Browser and browse this on Gemini. I recommend Lagrange. Or feel free to keep using HTTP. I've been on Gemini for more than half a year now. I genuinely feel the geminispace is a great place to be. And to publish my thoughts....

2022-04-11: Common Gemini crawler pitfalls

Just like the common web, crawlers on Gemini can run into similar pitfalls. Though the impact is much lower. The gemtext format is much smaller than HTML. And since Gemini does not support reusing the TCP connection. It takes much longer to mass-crawl a single capsule. Likely I can catch some issu...

2022-04-02: landlock-unveil - experimental unveil(2) for Linux

OpenBSD's unveil(2) is a great tool to protect the system in case a program gets compromised. Linux has (almost) nothing like it. You can do something close with seccomp and BPF. But it's waaaay out of the scope for any ordinary developer. Linux 5.13 introduces landlock, which provides more or le...

2022-03-31: Markdown is not context free (or, writing parsers vs perser combinators)

If you visit my blog posts over Gemini[1]. You'll see even though all my posts are written in Gemtext[2]. Due to the high frequency that I need to seperate inline code from text. I still use backticks for code blocks even it's not a standard in Gemtext. It' just feels natural. And so my Gemtext to...

2022-03-27: How to boost VRChat FPS using VR Performance Kit

VRChat is a great game. Probably the only MMO that is not a RPG (Besides one time my friend mentioned it's actually a MMO*ERP*G. Hehe). However the performance can be absolutely awful. Mostly maps not using LoD or avatars with 1M+ polygons. My PC, running a Ryzen 3700X + GTX 970 can only get a p...

2022-03-27: 如何使用 VR Performance Kit 提升 VRChat 的性能

VRChat的性能有時非常的糟糕。常常地圖不支援 LoD,是路人開著 > 100萬三角形的avatar等等... 我的自認不算太差電腦,Ryzen 3700X + GTX 970 也只能在我的 home world 跑到36 FPS(Quest 2,中間用AirLink + Wifi 6跟主機連線。地圖:Rainy Attic + 鏡子)。 國外的工程師 fholger 也遇到類似的問題,於是開發了VR Performance Kit。在我的主機上由原先的36FPS: 提升到約略維持在72左右。相片中只有54是因為用了遊戲內的相機拍照,導致GPU必須多負荷相機的計算。 如果你...

2022-03-20: The design of TLGS's crawler

TLGS is a search engine. Crawling is a very important part of it's oprtation. A crawler must follow links that it sees, retrive the page and follow more links on that page. While writing a basic crawler with DFS is relatively easy. Implementing a crawler that handles concurrent crawls well, runs o...

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Author's profile
Martin Chang
Systems software, HPC, GPGPU and AI. I mostly write stupid C++ code. Sometimes does AI research. Chronic VRChat addict

I run TLGS, a major search engine on Gemini. Used by Buran by default.


  • marty1885 \at protonmail.com
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