Provide a mechanism for dumping of heap profiles on predefined events.

runtime/vm/exceptions.cc

Index: runtime/vm/exceptions.cc
diff --git a/runtime/vm/exceptions.cc b/runtime/vm/exceptions.cc
index ba1dae4cab67ea1d0ddb4139066cd06e4713c278..214a32e30c2a43b22a42e948d0f655d4c759e164 100644
--- a/runtime/vm/exceptions.cc
+++ b/runtime/vm/exceptions.cc
@@ -9,6 +9,7 @@
 #include "vm/debugger.h"
 #include "vm/flags.h"
 #include "vm/object.h"
+#include "vm/object_store.h"
 #include "vm/stack_frame.h"
 #include "vm/stub_code.h"
 #include "vm/symbols.h"
@@ -16,7 +17,9 @@
 namespace dart {
 
 DEFINE_FLAG(bool, print_stacktrace_at_throw, false,
-    "Prints a stack trace everytime a throw occurs.");
+            "Prints a stack trace everytime a throw occurs.");
+DEFINE_FLAG(bool, heap_profile_out_of_memory, false,
+            "Writes a heap profile on unhandled out-of-memory exceptions.");
 
 
 const char* Exceptions::kCastErrorDstName = "type cast";
@@ -166,6 +169,22 @@ static void ThrowExceptionHelper(const Instance& incoming_exception,
     // There are no dart invocation frames on the stack so we do not
     // have a caller to return to.
     ASSERT(!handler_exists);
+    if (FLAG_heap_profile_out_of_memory) {
+      Isolate* isolate = Isolate::Current();
+      Instance& out_of_memory =
+          Instance::Handle(isolate->object_store()->out_of_memory());
+      if (incoming_exception.Equals(out_of_memory)) {
+        Instance& out_of_memory =
+            Instance::Handle(isolate->object_store()->out_of_memory());
+        if (incoming_exception.Equals(out_of_memory)) {

[siva, 2012/12/07 00:33:02]

The handle and if check seems to be repeated twice here?

[cshapiro, 2012/12/08 07:29:46]

Sorry about that.  I actually caught this earlier.  Removed.

+          const char* format = "%s-out-of-memory.hprof";
+          intptr_t len = OS::SNPrint(NULL, 0, format, isolate->name());
+          char* filename = isolate->current_zone()->Alloc<char>(len + 1);
+          OS::SNPrint(filename, len + 1, format, isolate->name());
+          isolate->heap()->ProfileToFile(filename);

[siva, 2012/12/07 00:33:02]

Why not change the signature of ProfileToFile to be
void ProfileToFile(const char* suffix_name) const;

That way you could move all the filename computation code into ProfileToFile and
not have have to repeat it in two places.

e.g:

isolate->heap()->ProfileToFile("isolate-initialize");
isolate->heap()->ProfileToFile("isolate-out-of-memory");

[cshapiro, 2012/12/08 07:29:46]

Good idea.  Done.  (Saves ~3 places, actually.)

+        }
+      }
+    }
     if (Isolate::UnhandledExceptionCallback() != NULL) {
       // Notify embedder that an unhandled exception occurred.
       Dart_EnterScope();