introduce nimMaxHeap define to fight memory overcommit

1 files changed, 5 insertions, 0 deletions

diff --git a/lib/system/alloc.nim b/lib/system/alloc.nim
index a124d7537..f28a124d2 100644
--- a/lib/system/alloc.nim
+++ b/lib/system/alloc.nim
@@ -292,10 +292,15 @@ proc writeFreeList(a: MemRegion) =
               it, it.next, it.prev, it.size)
     it = it.next
 
+const nimMaxHeap {.intdefine.} = 0
+
 proc requestOsChunks(a: var MemRegion, size: int): PBigChunk =
   when not defined(emscripten):
     if not a.blockChunkSizeIncrease:
       let usedMem = a.currMem # - a.freeMem
+      when nimMaxHeap != 0:
+        if usedMem > nimMaxHeap * 1024 * 1024:
+          raiseOutOfMem()
       if usedMem < 64 * 1024:
         a.nextChunkSize = PageSize*4
       else: