wasi_gc_crash.go

package main

import (
	"fmt"
	"time"

	"github.com/bytecodealliance/wasmtime-go"
)

func prepare(wasmfile string) (*wasmtime.Store, *wasmtime.WasiInstance, *wasmtime.Module) {
	config := wasmtime.NewConfig()
	config.SetDebugInfo(true)
	config.SetWasmMultiValue(true)

	store := wasmtime.NewStore(wasmtime.NewEngineWithConfig(config))
	wasm, err := wasmtime.Wat2Wasm(`
      (module
        (import "" "hello" (func $hello))
        (func (export "run")
          (call $hello))
      )
    `)
	check(err)
	module, err := wasmtime.NewModule(store, wasm)
	check(err)

	// These options ensure our wasm module can write to stdout/stderr
	wasicfg := wasmtime.NewWasiConfig()
	wasicfg.InheritStdout()
	wasicfg.InheritStderr()
	wasi, err := wasmtime.NewWasiInstance(store, wasicfg, "wasi_snapshot_preview1")
	check(err)

	return store, wasi, module
}

func main() {
	store, wasi, module := prepare("bin/main.wasm")
	_, _, _ = store, wasi, module

	fmt.Println("Waiting..")

	// Sleep for just over 2 minutes, which will get the runtime to force a GC
	// Doesn't reliably work at 121 seconds, so I set to 130.
	time.Sleep(130 * time.Second)

	fmt.Println("And now...the crash.")

	// And then do something else, letting the runtime force the GC
	<-time.After(1 * time.Second)

	// Note that the time.Sleep & time.After can be replaced with:
	// http.ListenAndServe(":", nil)
	// The end result is the same thing, in ~2 minutes the runtime forces a GC and we segfault
	fmt.Println("Back up!")
}

func check(err error) {
	if err != nil {
		fmt.Printf("Got error: %s\n", err.Error())
		panic(err)
	}
}