Add multithreaded test infrastructure with Shuttle

[LucasSte]

Problem

The program cache has multiple synchronization mechanisms without any systemic test infrastructure. Although PR #1471 introduced an adhoc test for program cache, it is insufficient for finding issues in the code.

Summary of Changes

I want to adopt shuttle to run specialized multithreaded test in the CI. In order for it to work, all sync, rand and thread imports must come from shuttle.

[alessandrod]

instead of cfging shuttle everywhere, we could have an internal thread module somewhere that imports the OG stuff or shuttle depending on cfg.

[LucasSte]

instead of cfging shuttle everywhere, we could have an internal thread module somewhere that imports the OG stuff or shuttle depending on cfg.

Do you mean another create in the monorepo? I need the shuttle imports across multiple crates, so a module in one of the existing ones wouldn't work I guess.

[alessandrod]

instead of cfging shuttle everywhere, we could have an internal thread module somewhere that imports the OG stuff or shuttle depending on cfg.

Do you mean another create in the monorepo? I need the shuttle imports across multiple crates, so a module in one of the existing ones wouldn't work I guess.

Hmm, with some luck there's a crate that is imported by pretty much everything? sdk? :D

[LucasSte]

instead of cfging shuttle everywhere, we could have an internal thread module somewhere that imports the OG stuff or shuttle depending on cfg.

Do you mean another create in the monorepo? I need the shuttle imports across multiple crates, so a module in one of the existing ones wouldn't work I guess.

Hmm, with some luck there's a crate that is imported by pretty much everything? sdk? :D

That would surely work, but enforcing people to use the right import would be difficult.

[alessandrod]

instead of cfging shuttle everywhere, we could have an internal thread module somewhere that imports the OG stuff or shuttle depending on cfg.

Do you mean another create in the monorepo? I need the shuttle imports across multiple crates, so a module in one of the existing ones wouldn't work I guess.

Hmm, with some luck there's a crate that is imported by pretty much everything? sdk? :D

That would surely work, but enforcing people to use the right import would be difficult.

wouldn't be more difficult than making them import shuttle?

[LucasSte]

instead of cfging shuttle everywhere, we could have an internal thread module somewhere that imports the OG stuff or shuttle depending on cfg.

Do you mean another create in the monorepo? I need the shuttle imports across multiple crates, so a module in one of the existing ones wouldn't work I guess.

Hmm, with some luck there's a crate that is imported by pretty much everything? sdk? :D

That would surely work, but enforcing people to use the right import would be difficult.

wouldn't be more difficult than making them import shuttle?

Fair point. There are drawbacks in both approaches. On one hand, people may forget to add the shuttle import, on the other, they may still import from std::sync, instead of solana_sdk::sync (for example).

[LucasSte]

I'm open to changing then. Anyone else wants to weight in? @Lichtso and @pgarg66 ?

[LucasSte]

Closing this PR in favor of #1634.