There seems to be a memory leak in the Higgs compiler. This
problem shows up when running our test suite (`make test`
command).
A new VM object is created for each unittest block, e.g.:
https://github.com/maximecb/Higgs/blob/master/source/runtime/tests.d#L201
These VM objects are unfortunately *never freed*. Not until the
whole series of tests is run and the process terminates. The VM
objects keep references to many other objects, and so the process
keeps using more and more memory, up to over 2GB.
The VM allocates it's own JS data heap that it manages itself,
i.e.:
https://github.com/maximecb/Higgs/blob/master/source/runtime/gc.d#L186
This memory is clearly marked as NO_SCAN, and so references to
the VM in there should presumably not be counted. There is also
executable memory I allocate with mmap, but this should also be
ignored by the D GC in principle (I do not mark executable code
as roots):
https://github.com/maximecb/Higgs/blob/master/source/jit/codeblock.d#L129
I don't know where the problem lies. There could be false
pointers, but I'm on a 64-bit system, which should presumably
make this less likely. I wish there was a way to ask the D
runtime "can you tell me what is pointing to this object?", but
the situation is more complex because many objects in my system
refer to the VM object, there is a complicated graph of
references. If anything points into that graph, the whole thing
stays "live".
Help or advice on solving this problem is welcome.
