Profiling is unecessary slow
Open
@guibou is already working on this.
Since Sep 10, 2018.
P3
type: bug
- Dominant language
- Starlark
- Stars
- 279
- Forks
- 93
- Avg merge
- 13d 11h
- Merged PRs (30d)
- 3
Description
This is an updated description which summarize the discussion
- Building with
-c dbgis really slow when template haskell is used because we use-fexternal-interpreterand this GHC bug: https://ghc.haskell.org/trac/ghc/ticket/16256#ticket . In summary, profiling build is 15x times slower than normal build. - There is two solutions to build haskell with profiling if template haskell is involved.
-fexternal-interpreter, which is now used in rules_haskell, and another solution which build two times, once without profiling (so template haskell can execute non profiled code) and one with profiling. - rules_haskell was initially using the two build solution, but the switch to
-fexternal-interpreterwas accidentally done in be5cf67#diff-33a8c46955e2a9917090b5258346aee2R205. Since #892 the dead code of the two build solution was removed.
We have two solution here:
- Keep the approach with
-fexternal-interpreterand wait for an upstream fix for GHC - Get back to the approach without
-fexternal-interpreterand reimplement the two steps build.
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