Alex Vidal (May 22 2020 at 16:08): Alex Vidal (May 22 2020 at 16:08):I'm working on a project that uses the Go bindings for wasmtime, and if I create two instances from the same store, wasi instance, and module I get a call stack exhausted panic when I try to call the entrypoint func. I also tried to construct a new wasi instance for each module instance, but no difference. Am I misunderstanding something?
Alex Crichton (May 22 2020 at 16:09):@Alex Vidal hm what does the stack trace look like?
Alex Vidal (May 22 2020 at 16:10):wasm backtrace: 0: 0xffffffff - <unknown>!_start
Alex Vidal (May 22 2020 at 16:12):In my specific case my wasm program calls out to the host, and the host sleeps for 1s. I can try to repro by sleeping inside the wasm program instead.
Alex Vidal (May 22 2020 at 16:12):(the sleep isn't normal operation, just for my reproduction)
Alex Crichton (May 22 2020 at 16:14):hm is that the only stack frame?
Alex Crichton (May 22 2020 at 16:14):oh you know that actually looks like a segfault
Alex Crichton (May 22 2020 at 16:14):rather than a stack exhausted panic
Alex Crichton (May 22 2020 at 16:14):do you have some code I could poke at?
Alex Vidal (May 22 2020 at 16:16):i can try to reproduce it without all my nonsense
Alex Vidal (May 22 2020 at 16:24):ok i can repro it easily
Alex Vidal (May 22 2020 at 16:24):sending up a branch
Alex Vidal (May 22 2020 at 16:28):https://github.com/avidal/wasmtime-go/blob/concurrent-segfault/repro_test.go
Alex Vidal (May 22 2020 at 16:30):the wasi stuff is a red herring it's not necessary for the reproduction
Alex Vidal (May 22 2020 at 16:31):run it with go test -v -run Repro and all but the first subtest will fail
Alex Crichton (May 22 2020 at 16:33):ah I see, so currently nothing in Store can be used concurrently
Alex Crichton (May 22 2020 at 16:33):so believe this is segfaulting due to data races
Alex Crichton (May 22 2020 at 16:33):everything within a Store must be locked to the same goroutine
Alex Vidal (May 22 2020 at 16:34):hm, but i can't get a compiled module without a store..
Alex Vidal (May 22 2020 at 16:36):My program currently instantiates for each incoming http request to avoid the setup costs. I suppose I'll need to use a pool instead and pre-fill it with a handful of stores.
Alex Crichton (May 22 2020 at 16:47):@Alex Vidal ah yeah currently it's a limitation that you need to compile once-per-thread
Alex Crichton (May 22 2020 at 16:47):we very much want to lift that limitation soon
Alex Vidal (May 22 2020 at 16:56):ok cool. I'll setup a pool for now then. Is there a tracking issue I can subscribe to?
Alex Crichton (May 22 2020 at 16:58):https://github.com/bytecodealliance/wasmtime/issues/793 is probably the closest equivalent
Last updated: Nov 22 2024 at 16:03 UTC