ORC: make the adaptive strategy the default in order to fight memory consumption (#16250)

* ORC: make the adaptive strategy the default in order to fight memory consumption

* added missing test case

tests/arc/tasyncleak.nim

@@ -1,5 +1,5 @@
 discard """
-  outputsub: "(allocCount: 4014, deallocCount: 4012)"
+  outputsub: "(allocCount: 4302, deallocCount: 4300)"
   cmd: "nim c --gc:orc -d:nimAllocStats $file"
 """
 

tests/arc/torcbench.nim

@@ -0,0 +1,38 @@
+discard """
+  output: '''true peak memory: true'''
+  cmd: "nim c --gc:orc -d:release $file"
+"""
+
+import lists, strutils, times
+
+type
+  Base = ref object of RootObj
+
+  Node = ref object of Base
+    parent: DoublyLinkedList[string]
+    le, ri: Node
+    self: Node # in order to create a cycle
+
+proc buildTree(parent: DoublyLinkedList[string]; depth: int): Node =
+  if depth == 0:
+    result = nil
+  elif depth == 1:
+    result = Node(parent: parent, le: nil, ri: nil, self: nil)
+    when not defined(gcArc):
+      result.self = result
+  else:
+    result = Node(parent: parent, le: buildTree(parent, depth - 1), ri: buildTree(parent, depth - 2), self: nil)
+    result.self = result
+
+proc main() =
+  for i in countup(1, 100):
+    var leakList = initDoublyLinkedList[string]()
+    for j in countup(1, 5000):
+      leakList.append(newString(200))
+    #GC_fullCollect()
+    for i in 0..400:
+      discard buildTree(leakList, 8)
+
+main()
+GC_fullCollect()
+echo getOccupiedMem() < 10 * 1024 * 1024, " peak memory: ", getMaxMem() < 10 * 1024 * 1024