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Decrease default wasm stack to 512k from 1M (#3861)

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This commit aims to achieve the goal of being able to run the test suite
on Windows with `--test-threads 1`, or more notably allowing Wasmtime's
defaults to work better with the main thread on Windows which appears to
have a smaller stack by default than Linux by comparison. In decreasing
the default wasm stack size a test is also update to probe for less
stack to work on Windows' main thread by default, ideally allowing the
full test suite to work with `--test-threads 1` (although this isn't
added to CI as it's not really critical).

Closes #3857
This commit is contained in:
Alex Crichton
2022-02-28 12:18:11 -06:00
committed by GitHub
parent 24f145cd1e
commit aeaca2062f
2 changed files with 12 additions and 4 deletions
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12
crates/wasmtime/src/config.rs
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@@ -115,7 +115,15 @@ impl Config {
profiler: Arc::new(NullProfilerAgent), profiler: Arc::new(NullProfilerAgent),
mem_creator: None, mem_creator: None,
allocation_strategy: InstanceAllocationStrategy::OnDemand, allocation_strategy: InstanceAllocationStrategy::OnDemand,
max_wasm_stack: 1 << 20, // 512k of stack -- note that this is chosen currently to not be too
// big, not be too small, and be a good default for most platforms.
// One platform of particular note is Windows where the stack size
// of the main thread seems to, by default, be smaller than that of
// Linux and macOS. This 512k value at least lets our current test
// suite pass on the main thread of Windows (using `--test-threads
// 1` forces this), or at least it passed when this change was
// committed.
max_wasm_stack: 512 * 1024,
wasm_backtrace_details_env_used: false, wasm_backtrace_details_env_used: false,
features: WasmFeatures::default(), features: WasmFeatures::default(),
#[cfg(feature = "async")] #[cfg(feature = "async")]
@@ -444,7 +452,7 @@ impl Config {
/// on stack overflow, a host function that overflows the stack will /// on stack overflow, a host function that overflows the stack will
/// abort the process. /// abort the process.
/// ///
/// By default this option is 1 MiB. /// By default this option is 512 KiB.
pub fn max_wasm_stack(&mut self, size: usize) -> Result<&mut Self> { pub fn max_wasm_stack(&mut self, size: usize) -> Result<&mut Self> {
#[cfg(feature = "async")] #[cfg(feature = "async")]
if size > self.async_stack_size { if size > self.async_stack_size {

4
tests/all/stack_overflow.rs
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@@ -4,8 +4,8 @@ use wasmtime::*;
#[test] #[test]
fn host_always_has_some_stack() -> anyhow::Result<()> { fn host_always_has_some_stack() -> anyhow::Result<()> {
static HITS: AtomicUsize = AtomicUsize::new(0); static HITS: AtomicUsize = AtomicUsize::new(0);
// assume hosts always have at least 512k of stack // assume hosts always have at least 128k of stack
const HOST_STACK: usize = 512 * 1024; const HOST_STACK: usize = 128 * 1024;
let mut store = Store::<()>::default(); let mut store = Store::<()>::default();