Hi,
We're struggling to get our build pipeline working on CircleCI, which has a 4GB RAM limit. Here are some project stats to set the context:
- 1,200+ modules
- 36,315 LoC of Haskell
- On the local machine with -O1 -j the build takes approx 5.2 GB of RAM [1]
Trying to build on CircleCI with -O1 -j fails consistently, as expected. However, the behaviour of -M -j -O1 is erratic, at best. Sometimes it magically works, sometimes it fails. A number of times we've seen GHC take 3.5 GB (as reported by `top`), even though the limit was set to 2.5GB. Here are flags that we've tried in various combinations we've tried. None of them is consistent in building / failing:
* -O1
* -j
* +RTS -n2m -RTS
What is the **real** behaviour of the -M option? How does it interact with -j and -A?
-- Saurabh.