Use Data.Map.Strict instead of Data.Map

[phagenlocher]

When trying to read a 93Mb Dhall file with inputExprWithSettings (using a small list of subtitutions), Dhall currently crashes due to a spaceleak (presumably). Profiling showed that Dhall.Map is to blame for the allocations (with toList being the main retainer) and the only way to get this under control was to switch to Data.Map.Strict.

Is there a specific reason why the lazy Data.Map is used in this module? It seems to me that laziness provides no benefit and moving to the strict version is the way to go.

Profiling eventlogs (for a smaller file) can be found here: profiling.zip

[winitzki]

Not sure why the Hydra build failed.

[phagenlocher]

Not sure why the Hydra build failed.

@winitzki This shouldn't be related to the code changes, right?

[winitzki]

Not sure why the Hydra build failed.

@winitzki This shouldn't be related to the code changes, right?

Right, I believe it has nothing to do with the code changes. All tests passed in this PR. A similar situation is happening right now in another PR: #2513

Most likely it's a stale failed build that Hydra has cached for some reason. Someone needs to restart the server somewhere.

[Gabriella439]

Yeah, this is an issue with Hydra where it sometimes run out of memory and then I log in to manually restart the build. The main reason I still use Hydra is because it ensures that the cache is preserved between builds, which at the time was hard to get with other CI solutions. However, I have been thinking of switching to Garnix for Nix builds, which would fix this problem (I think).

[TristanCacqueray]

@Gabriella439 there is also DeterminateSystems/magic-nix-cache-action@main to keep the cache between GitHub actions, perhaps that would work for Dhall?