I have CircleCI set up to test my project when I push to GitHub.

For a free user there the memory restriction is pretty severe (4 Gb), and as such non-trivial programs cannot be compiled without separate compilation.

This sounded like a clear-cut case for -lowmem, but the process is still killed from allocating too much.

circleci@ab1d64fc40cf:~/project$ dub test
Running custom 'unittest' configuration.
Performing "unittest" build using /usr/bin/dmd for x86_64.
cachetools 0.1.2: building configuration "library"...
requests 1.0.8: building configuration "std"...
kameloso 1.1.3+commit.31.g11ba25fd: building configuration "unittest"...
Killed
/usr/bin/dmd failed with exit code 137.

dub test -v shows -lowmem being properly passed to dmd.

What makes it decide to collect? What triggers it?

On Sunday, 19 May 2019 at 23:54:27 UTC, Anonymouse wrote:
> Tweakig

I'd edit the title if I could. Grumble mutter.

On Sunday, 19 May 2019 at 23:54:27 UTC, Anonymouse wrote:
> What makes it decide to collect? What triggers it?

You can try setting heapSizeFactor option to something lower than 2 to increase collection frequency:
https://github.com/dlang/druntime/blob/47b03c14a1097d28afcf22f645628ba4046377bd/src/core/gc/config.d#L26
https://dlang.org/spec/garbage.html#gc_config

dmd appears to respect DRT_GCOPT environment variable.

The logic behind the decision to collect, I'm afraid, is not described anywhere but the code itself (https://github.com/dlang/druntime/blob/47b03c14a1097d28afcf22f645628ba4046377bd/src/gc/impl/conservative/gc.d#L1690)

On Monday, 20 May 2019 at 13:41:15 UTC, Boris-Barboris wrote:
> On Sunday, 19 May 2019 at 23:54:27 UTC, Anonymouse wrote:
>> What makes it decide to collect? What triggers it?
>
> You can try setting heapSizeFactor option to something lower than 2 to increase collection frequency:
> https://github.com/dlang/druntime/blob/47b03c14a1097d28afcf22f645628ba4046377bd/src/core/gc/config.d#L26
> https://dlang.org/spec/garbage.html#gc_config
>
> dmd appears to respect DRT_GCOPT environment variable.

This does look like what I need. I'm having no luck with DRT_GCOPT though.

$ dmd "--DRT-gcopt=heapSizeFactor=1.5 profile:1" hello.d
        Number of collections:  2
        Total GC prep time:  0 milliseconds
        Total mark time:  0 milliseconds
        Total sweep time:  0 milliseconds
        Total page recovery time:  0 milliseconds
        Max Pause Time:  0 milliseconds
        Grand total GC time:  0 milliseconds
GC summary:    5 MB,    2 GC    0 ms, Pauses    0 ms <    0 ms

$ DRT_GCOPT="heapSizeFactor=1.5 profile:1" dmd hello.d
[no output]

Are you sure dmd honours it? I can't grep rt_envvars_enabled in the dmd sources.

How can I otherwise get dub to pass these onto dmd?