Today I Learned on hungln

Go Http Timeout

Tue, 07 Apr 2026 15:44:09 +0700

SetDeadline

To implement timeouts in Go, network primitives expose deadlines via net.Conn.Set[Read|Write]Deadline

“Deadlines are not timeouts.” They represent an absolute point in time. If an I/O operation does not complete before that moment, it fails with a timeout error.

Because deadlines are absolute, they do not automatically reset after each read or write. That means you must explicitly call SetDeadline before every I/O operation.

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func handle(conn net.Conn) {
 timeout := 5 * time.Second

 for {
 /// Deadline must be an absolute time (Now + Duration)
 conn.SetDeadline(time.Now().Add(timeout))

 buf := make([]byte, 1024)
 n, err := conn.Read(buf)

 if err != nil {
 // If err is a timeout, it's because the absolute time was reached
 return
 }

 // Process buf[:n]...
 }
}

If you set the deadline only once (outside the loop), the connection will expire after the initial timeout window and all subsequent operations will fail.

ASCII vs. UTF-8

Mon, 30 Mar 2026 16:33:40 +0700

The 7-Bit History of ASCII

In the 1960s, ASCII used only 7 bits ($2^7 = 128$ characters). The final bit was reserved for a Parity Bit to check for hardware errors during transmission. Because of this design, standard ASCII only covers the range 0x00 to 0x7F.

In modern systems, parity bits are no longer used for character encoding, so the first bit of a standard ASCII character is always set to 0.

Zero Values in Go

Thu, 22 May 2025 21:35:22 +0700

Each type in Go has a zero value, which is the default value assigned to a variable of that type when it is declared but not explicity initialized.

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var boolean bool // false
var integer int // 0
var float float64 // 0.0
var complex complex128 // (0+0i)
var str string // ""
var array [5]int // [0 0 0 0 0]
var slice []int // nil
var mapVar map[string]int // nil
var channelVar chan int // nil
var pointer *int // nil
var functionVar func() // nil
var interfaceVar interface{} // nil

Detect Data Race in Go

Sat, 17 May 2025 17:44:46 +0700

In Go, to detect data race, we can use the -race flag when running or testing our code.

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go run -race main.go