Ryan,
That makes perfect sense, thanks. Is that documented explicitly anywhere?
If not, I'd like to add the documentation to any place relevant.
Thanks
On Thu, Jan 17, 2019, 8:19 PM Ryan Yates Hi, Because GHC's GC is generational it needs a way to handle heap objects
from older generations that point into younger generations. This only
happens when an older object is mutated to point to a younger object. GHC
solves this by invoking the GC write barrier (not to be confused with write
barriers for memory synchronization) `dirty_MUT_VAR`. This will add that
mutable object to a mutable list that will be traversed in minor GCs along
with young generation roots. Additionally the write barrier will mark the
heap object as "dirty" to avoid adding it to the list more than once. Ryan On Thu, Jan 17, 2019 at 4:29 PM chessai . Devs, I've heard from a few friends that MutVars, TVars, etc. are more
challenging for the garbage collector. I'm writing to ask if someone can
answer: 1. Is this true, and 2: Why? I can't seem to find anything like a
writeup or documentation that mentions this. The HeapObjects trac page also
mentions nothing about these supposed difficulties that GC faces with
mutable heap objects. Thanks
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