When maximum space size flags are set, overwrite the resource constraints.

src/api.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "api.h"
 
 #include <string.h>  // For memcpy, strlen.
 #include <cmath>  // For isnan.
 #include "../include/v8-debug.h"
 #include "../include/v8-profiler.h"
@@ skipping 443 matching lines @@
     set_max_old_space_size(i::Heap::kMaxOldSpaceSizeHighMemoryDevice);
     set_max_executable_size(i::Heap::kMaxExecutableSizeHighMemoryDevice);
   } else {
     set_max_new_space_size(i::Heap::kMaxNewSpaceSizeHugeMemoryDevice);
     set_max_old_space_size(i::Heap::kMaxOldSpaceSizeHugeMemoryDevice);
     set_max_executable_size(i::Heap::kMaxExecutableSizeHugeMemoryDevice);
   }
 
   set_max_available_threads(i::Max(i::Min(number_of_processors, 4u), 1u));
 
+  if (i::FLAG_max_new_space_size > 0) {
+    set_max_new_space_size(i::FLAG_max_new_space_size * i::Heap::kLumpOfMemory);
+  }
+  if (i::FLAG_max_old_space_size > 0) {
+    set_max_old_space_size(i::FLAG_max_old_space_size * i::Heap::kLumpOfMemory);
+  }
+  if (i::FLAG_max_executable_size > 0) {
+    set_max_executable_size(
+        i::FLAG_max_executable_size * i::Heap::kLumpOfMemory);
+  }
+

[rmcilroy, 2014/04/30 12:17:13]

Would it be better to put this code in Heap::ConfigureHeap()?  That way the
flags would be respected even if the embedder passed their own custom created
ResourceConstraints via SetResourceConstraints?

[Hannes Payer (out of office), 2014/04/30 12:36:22]

Yeah, makes sense. Done.

   if (virtual_memory_limit > 0 && i::kIs64BitArch) {
     // Reserve no more than 1/8 of the memory for the code range, but at most
     // 512 MB.
     set_code_range_size(
         i::Min(512 * i::MB, static_cast<int>(virtual_memory_limit >> 3)));
   }
 }
 
 
 bool SetResourceConstraints(Isolate* v8_isolate,
@@ skipping 7108 matching lines @@
   Isolate* isolate = reinterpret_cast<Isolate*>(info.GetIsolate());
   Address callback_address =
       reinterpret_cast<Address>(reinterpret_cast<intptr_t>(callback));
   VMState<EXTERNAL> state(isolate);
   ExternalCallbackScope call_scope(isolate, callback_address);
   callback(info);
 }
 
 
 } }  // namespace v8::internal