I'm trying to tweak the GC when compiling with dub, starting with
something easy like profile:1.
$ grep dflags dub.json
"dflags": [ "-lowmem", "--DRT-gcopt=profile:1" ],
$ dub test
Doesn't work, doesn't give any extra output. Entering bogus flags
like --DRT-gcopt=banana:1 doesn't evoke any error message either,
making me doubt it's being passed on at all.
$ dmd -oftest -lowmem --DRT-gcopt=profile:1 source/**/*.d
Number of collections: 13
Total GC prep time: 7 milliseconds
Total mark time: 2110 milliseconds
Total sweep time: 270 milliseconds
Total page recovery time: 204 milliseconds
Max Pause Time: 472 milliseconds
Grand total GC time: 2592 milliseconds
GC summary: 1099 MB, 13 GC 2592 ms, Pauses 2117 ms < 472 ms
Manual dmd invocation does work, so it's not like dmd is ignoring
--DRT-gcopt.
$ dub test --DRT-gcopt=profile:1
[...]
Number of collections: 10
Total GC prep time: 0 milliseconds
Total mark time: 4 milliseconds
Total sweep time: 7 milliseconds
Total page recovery time: 4 milliseconds
Max Pause Time: 0 milliseconds
Grand total GC time: 15 milliseconds
GC summary: 12 MB, 10 GC 15 ms, Pauses 4 ms < 0 ms
The totals should be in the ballpark of 1Gb+ (as above), not
12Mb. Is it only profiling dub itself? (Incidentally this is
roughly what dmd reports if called without -lowmem.)
$ export DRT_GCOPT=profile:1
$ dub test
Doesn't work either, I can't actually get the env var to affect
dmd at all, even when manually running it.
What is the correct way?
