Rank most retaining instances for each class.

Rank most retaining instances for each class.

Keep a heap snapshot (object graph) in the isolate.
On request from a class view, show 10 most retaining instances.

Currently, a new snapshot is fetched every time a ranking is requested.
In the future, we will want more fine-grained management of snapshots,
with its own dedicated view/console.

R=johnmccutchan@google.com

Committed: https://code.google.com/p/dart/source/detail?r=42754

[Cutch, 2015-01-06 23:20:21]

Hi,

Can you rebase this and then I'll review it ASAP.

Thanks,
John

[koda, 2015-01-07 00:03:34]

Done.

[Cutch, 2015-01-07 00:25:27]

https://codereview.chromium.org/818733002/diff/40001/runtime/observatory/lib/...
File runtime/observatory/lib/object_graph.dart (right):

https://codereview.chromium.org/818733002/diff/40001/runtime/observatory/lib/...
runtime/observatory/lib/object_graph.dart:81: vertices.where((u) => u.classId !=
0));
Perhaps make this magic number into a const and document it.

https://codereview.chromium.org/818733002/diff/40001/runtime/observatory/lib/...
File runtime/observatory/lib/src/elements/class_view.html (right):

https://codereview.chromium.org/818733002/diff/40001/runtime/observatory/lib/...
runtime/observatory/lib/src/elements/class_view.html:182: <div
class="memberName">most retaining objects</div>
I think this needs more explanation for developers. What about 'instances of
this class that hold the most memory'?

https://codereview.chromium.org/818733002/diff/40001/runtime/observatory/lib/...
File runtime/observatory/lib/src/service/object.dart (right):

https://codereview.chromium.org/818733002/diff/40001/runtime/observatory/lib/...
runtime/observatory/lib/src/service/object.dart:696: class HeapSnapshot extends
Observable {
Why does this class extend from Observable?

https://codereview.chromium.org/818733002/diff/40001/runtime/observatory/lib/...
runtime/observatory/lib/src/service/object.dart:884: Completer<HeapSnapshot>
snapshotFetch;
Any reason why snapshotFetch is public?

https://codereview.chromium.org/818733002/diff/40001/runtime/observatory/lib/...
runtime/observatory/lib/src/service/object.dart:886: void
loadHeapSnapshot(ServiceEvent event) {
Any reason why this is public?

...

I see now that we call it from app. We should probably revisit event delivery at
some point.

[koda, 2015-01-09 18:46:56]

PTAL

https://codereview.chromium.org/818733002/diff/40001/runtime/observatory/lib/...
File runtime/observatory/lib/object_graph.dart (right):

https://codereview.chromium.org/818733002/diff/40001/runtime/observatory/lib/...
runtime/observatory/lib/object_graph.dart:81: vertices.where((u) => u.classId !=
0));
On 2015/01/07 00:25:26, Cutch wrote:
> Perhaps make this magic number into a const and document it.

Added 'isRoot' getter.

https://codereview.chromium.org/818733002/diff/40001/runtime/observatory/lib/...
File runtime/observatory/lib/src/elements/class_view.html (right):

https://codereview.chromium.org/818733002/diff/40001/runtime/observatory/lib/...
runtime/observatory/lib/src/elements/class_view.html:182: <div
class="memberName">most retaining objects</div>
On 2015/01/07 00:25:26, Cutch wrote:
> I think this needs more explanation for developers. What about 'instances of
> this class that hold the most memory'?

Since it's in a class view, under subheading 'instances', it seems a bit
redundant to repeat those words. I went with "toplist by retained memory". See
screenshot sent separately.

https://codereview.chromium.org/818733002/diff/40001/runtime/observatory/lib/...
File runtime/observatory/lib/src/service/object.dart (right):

https://codereview.chromium.org/818733002/diff/40001/runtime/observatory/lib/...
runtime/observatory/lib/src/service/object.dart:696: class HeapSnapshot extends
Observable {
On 2015/01/07 00:25:26, Cutch wrote:
> Why does this class extend from Observable?

Done.

https://codereview.chromium.org/818733002/diff/40001/runtime/observatory/lib/...
runtime/observatory/lib/src/service/object.dart:884: Completer<HeapSnapshot>
snapshotFetch;
On 2015/01/07 00:25:26, Cutch wrote:
> Any reason why snapshotFetch is public?

Done.

https://codereview.chromium.org/818733002/diff/40001/runtime/observatory/lib/...
runtime/observatory/lib/src/service/object.dart:886: void
loadHeapSnapshot(ServiceEvent event) {
On 2015/01/07 00:25:26, Cutch wrote:
> Any reason why this is public?
> 
> ...
> 
> I see now that we call it from app. We should probably revisit event delivery
at
> some point.

Yes. I think there should be per-isolate event streams in addition to the global
one, but I didn't want to add that in this CL.

[Cutch, 2015-01-09 20:44:42]

lgtm

[koda, 2015-01-09 21:27:02]

Also worked around Dart2JS missing getUint64 by limiting metadata to 4GB.

[koda, 2015-01-09 21:31:20]

Committed patchset #5 (id:80001) manually as r42754 (presubmit successful).