wasmtime serve can't run components requiring >10MB of memory by default

[dicej]

Since wasmtime serve was switched to using the pooling allocator, which defaults to a memory limit of 10MB, components built with e.g. componentize-py or componentize-dotnet will no longer run by default. Also, since there is currently no CLI option to override that memory limit, the only workaround is to disable the pooling allocator entirely using wasmtime serve -O pooling-allocator=n.

I propose that we address this with the following changes:

• Increase the default memory limit in the pooling allocator to something like 100MB
• Allow the default to be overridden via a CLI option
• Provide a helpful suggestion to use that option when the component can't be run due to the memory limit

[dicej]

See also #8504 and bytecodealliance/componentize-py#94

[dicej]

Also, (mainly to help search engines find this issue) this is the kind of error message you get: Error: memory index 0 has a minimum page size of 223 which exceeds the limit of 160

[alexcrichton]

Can you test whether -Opooling-max-memory-size=N enables running these components? Sorry I keep meaning to raise the limit here and keep forgetting, but I also want to confirm orthogonally that this option works since that's what it's supposed to do

[dicej]

 $ wasmtime --version
wasmtime-cli 21.0.1 (cedf9aa0f 2024-05-22)
 $ wasmtime serve -Opooling-max-memory-size=160 -S cli target/component.wasm
error: unknown -O / --optimize option: pooling-max-memory-size

Maybe that's new on main?

[alexcrichton]

I think that might be Wasmtime 21+, what version do you have for that?

[dicej]

Sorry, just edited the comment; it's 21.0.1

[alexcrichton]

Oh sorry, for some reason I had Wasmtime 22 installed instead of the 21 version, which explains this!