initial commit

region_size.py

@@ -0,0 +1,38 @@
+import re
+import sys
+
+
+ONEMB = 1_048_576
+
+if len(sys.argv) != 2:
+    print("usage: python regionsize.py <gc_log>")
+    exit()
+
+log = sys.argv[1]
+f = open(log)
+allocations = []
+total = 0
+
+for line in f.read().splitlines():
+    if re.search("allocation request:.*source concurrent humongous allocation", line) is not None:
+        total += 1
+        req = re.search("allocation request: [0-9]+", line).group()
+        allocations.append(int(re.search(r"[0-9]+", req).group()))
+
+print(f"found {total} humongous objects in {log}")
+
+# humongous allocations occur when the request is >= 1/2 the region size
+
+mb2 = sum(map(lambda x: x < 1*ONEMB), allocations)
+mb4 = sum(map(lambda x: x < 2*ONEMB), allocations)
+mb8 = sum(map(lambda x: x < 4*ONEMB), allocations)
+mb16 = sum(map(lambda x: x < 8*ONEMB), allocations)
+mb32 = sum(map(lambda x: x < 16*ONEMB), allocations)
+mbMax = sum(map(lambda x: x >= 16*ONEMB), allocations)
+
+print(f"{100*mb2/total}% would not be humongous with a 2mb region size (-XX:G1HeapRegionSize)")
+print(f"{100*mb2/total}% would not be humongous with a 4mb region size")
+print(f"{100*mb2/total}% would not be humongous with a 8mb region size")
+print(f"{100*mb2/total}% would not be humongous with a 16mb region size")
+print(f"{100*mb2/total}% would not be humongous with a 32mb region size")
+print(f"{100*mb2/total}% would remain humongous with a 32mb region size")