Zio - async I/O framework

lalinsky · November 1, 2025, 10:58am

Have some ugly AI-made proofs of concepts, both for Windows using the native stack growth system and Linux using SIGSEGV handler (I think this one should work on other unixes as well).

github.com/lalinsky/zio

linux_stack_growth_poc.zig

rtl-user-stack-poc

// Linux lazy stack growth PoC using SIGSEGV handler
// Demonstrates true lazy commit with PROT_NONE + mprotect
//
// Build: zig build-exe linux_stack_growth_poc.zig -target x86_64-linux

const std = @import("std");
const builtin = @import("builtin");
const posix = std.posix;
const linux = std.os.linux;

comptime {
    if (builtin.os.tag != .linux) {
        @compileError("This PoC only works on Linux");
    }
}

const STACK_RESERVE_SIZE = 8 * 1024 * 1024; // 8 MB
const INITIAL_COMMIT_SIZE = 256 * 1024;     // 256 KB
const COMMIT_CHUNK_SIZE = 64 * 1024;        // Commit 64 KB at a time on fault
const PAGE_SIZE = 4096;

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github.com/lalinsky/zio

windows_stack_growth_recursive_poc.zig

rtl-user-stack-poc

// Windows automatic stack growth PoC using RtlCreateUserStack
// Demonstrates kernel-managed stack expansion via guard pages
//
// Build: zig build-exe windows_stack_growth_recursive_poc.zig -target x86_64-windows

const std = @import("std");
const builtin = @import("builtin");
const windows = std.os.windows;

comptime {
    if (builtin.os.tag != .windows) {
        @compileError("This PoC only works on Windows");
    }
}

const STACK_RESERVE_SIZE = 8 * 1024 * 1024; // 8 MB
const INITIAL_COMMIT_SIZE = 256 * 1024;     // 256 KB

// INITIAL_TEB structure
const INITIAL_TEB = extern struct {

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Looking forward to integrating this properly. Would allow me to start with e.g. 64KiB initial committed memory and grow up to let’s say 8MB.