$Dhruv👨‍💻 @dcodejs

Building what I don’t fully understand yet systems self everything Joined December 2024

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$Dhruv👨‍💻 @dcodejs

5 days ago

SSDs don’t really edit data in place Once data is written to a NAND page it can’t just be changed To update it the SSD writes the new data elsewhere marks the old page as invalid and later erases a whole block at once All this juggling is why SSDs feel so fast and reliable

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$Dhruv👨‍💻 @dcodejs

2 weeks ago

DMA lets peripherals access memory directly bypassing CPU VM switches reducing latency for high throughput lO Keyboards mice gain little CPU suffices DMA compromise = full memory access risk Too many processes hurt cache & scheduling Secure IOMMU configs help mitigate DMA threats

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$Dhruv👨‍💻 @dcodejs

2 weeks ago

In Node js every request is a stream It buffers about 16KB by default When full Node pauses writes After draining flow resumes This pause resume keeps memory safe like the stream knows when to breathe

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$Dhruv👨‍💻 @dcodejs

2 weeks ago

When you connect() to a TCP server your app doesn’t do the 3 way handshake The kernel handles it Only after it’s complete does the kernel tell your app Hey I’ve got a connection for you

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$Dhruv👨‍💻 @dcodejs

2 weeks ago

Node.js is great but sometimes you need raw speed That’s where C++ addons come in You can write performance heavy logic in C++ compile it with node-gyp and then just require() it like any other module Boom your Node app runs native binary code under the hood

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$Dhruv👨‍💻 @dcodejs

2 weeks ago

Node.js is single threaded by default… but you’ve got two ways to scale 👇 Worker Threads run in same process share memory good for CPU work but limited cores Child Processes spin up separate Node.js instances with cluster Cluster can balance with round robin or let OS decide

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$Dhruv👨‍💻 @dcodejs

2 weeks ago

In Node js server.listen(3000) often starts faster than server.listen(3000, "localhost") Why? Without a hostname it binds straight to 0.0.0.0 all interfaces With "localhost" Node has to resolve the name first usually through DNS or the hosts file

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$Dhruv👨‍💻 @dcodejs

2 weeks ago

In Nodejs server.listen(3000) often starts up faster than server.listen(3000, "localhost") Why? Without the hostname it just binds straight to 0.0.0.0 (all interfaces) With "localhost" Node has to resolve the name first usually via DNS/hosts file which adds a little overhead

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$Dhruv👨‍💻 @dcodejs

2 weeks ago

When multiple clients connect to a socket errors get queued in the pending callbacks list If one connection fails while another succeeds Node.js will process success first But… if the IP is loopback (127.0.0.1) it jumps to high priority in the queue!

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$Dhruv👨‍💻 @dcodejs

3 weeks ago

When you connect() to a TCP server the 3-way handshake isn’t done by your app it’s handled by the kernel Only after the handshake completes the kernel tells your app 👉 Hey I’ve got a connection for you

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$Dhruv👨‍💻 @dcodejs

3 weeks ago

process.nextTick() in Node.js is beautiful It runs right after the current operation before the event loop moves to the next phase Perfect for work you need done immediately before timers or I/O callbacks kick in

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$Dhruv👨‍💻 @dcodejs

3 weeks ago

It’s wild how setTimeout works You just say do this later and somehow it happens From what I get libuv basically tells the OS wake me up after X ms but if the event loop is busy the callback waits its turn So setTimeout is never 100% precise just at least that delay Still

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$Dhruv👨‍💻 @dcodejs

4 weeks ago

Ever start a Node.js server with no port? 🤔 Node quietly picks a random free one Want to catch it in the act? console.log(server.address().port) Great for quick local tests but not if the world needs to connect

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$Dhruv👨‍💻 @dcodejs

4 weeks ago

Using Buffer and streams Node can do zero-copy I/O No need to copy data from one buffer to another Just pass the reference the kernel handles the rest It’s how fs.createReadStream().pipe(res) sends GBs efficiently Less CPU Less RAM Just raw speed concat() kills zero-copy

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$Dhruv👨‍💻 @dcodejs

4 weeks ago

Just scrolling through Express source late at night Not debugging, not building just reading Trying to understand the thoughts behind the code we all use 💬 Sometimes the best way to grow is to read what others wrote when no one was watching

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$Dhruv👨‍💻 @dcodejs

4 weeks ago

await feels like a pause But the event loop never stops Your function sleeps Node keeps running A callback sits in the microtask queue Nothing blocks unless you block it No threads No magic Just promises Block the thread block it all Async in Node is cooperative not parallel