Documentation

Fields

• targetMap :: !(HashMap Target (HashSet NormalizedFilePath))
   
• normalisingMap :: !(HashMap Target Target)

  normalisingMap is a cached copy of `HMap.mapKey const targetMap`

  At startup GetLocatedImports is called on all known files. Say you have 10000 modules in your project then this leads to 10000 calls to GetLocatedImports running concurrently.

  In GetLocatedImports the known targets are consulted and the targetsMap is created by mapping the known targets. This map is used for introducing sharing amongst filepaths. This operation copies a local copy of the target map which is local to the rule.

  let targetsMap = HMap.mapWithKey const targets
  

  So now each rule has a HashMap of size 10000 held locally to it and depending on how the threads are scheduled there will be 10000^2 elements in total allocated in HashMaps. This used a lot of memory.

  Solution: Return the normalisingMap in the result of the GetKnownTargets rule so it is shared across threads.