The reason of that is a number of cons strings in the app.
The app constructs a json string and as a result v8 heap has
a very long chain of cons strings.
Profiler counts all these strings as plain String objects and
assign the content of the strings as node names.
It required O(n^2) time and O(n^2) memory.
Solution: I introduced two new types, kConsString and kSliced string.
They do not use the content of the string for names. So the problem disappeared.
The heap profiler usability problem will be solved on Blink side.
BUG=285770
R=yangguo@chromium.org
Review URL: https://codereview.chromium.org/23460027
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16611 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Current v8 implementation may disable optimization for a particular function or block it with help of dont_optimize flag.
The patch propagates the reason of that to the SharedFunctionInfo where cpu profiler can get it.
SharedFunctionInfo is a heap object so I extracted 8 bits from OptsCount for handling bailout reason code.
BUG=none
TEST=test-profile-generator/BailoutReason
R=yangguo@chromium.org
Review URL: https://codereview.chromium.org/23817003
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16555 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
All of these values are derived from the self samples count and there is no need to evaluate them in v8 when clients can do that when needed on their side.
Also added unsigned GetHitCount() which should be used instead of double GetSelfSamplesCount(). I'm going to deprecate the latter one once Blink has switched to GetHitCount.
BUG=267595
TBR=svenpanne@chromium.org
Review URL: https://codereview.chromium.org/22710006
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16119 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
The start and end time are now measured in microseconds and the type is int64_t.
This way it seems more natural as we are going to support submilisecond sampling
rate soon. Also it fixes cctest/test-cpu-profiler/ProfileStartEndTime test
failure caused by comparison between long double and double.
TEST=cctest/test-cpu-profiler/ProfileStartEndTime
BUG=v8:2824
R=bmeurer@chromium.org
Review URL: https://codereview.chromium.org/22155003
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16067 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
The start and end time are now measured in microseconds and the type is int64_t. This way it seems more natural as we are going to support submilisecond sampling rate soon. Also it fixes cctest/test-cpu-profiler/ProfileStartEndTime test failure caused by comparison between long double and double.
TEST=cctest/test-cpu-profiler/ProfileStartEndTime
BUG=v8:2824
R=alph@chromium.org, bmeurer@chromium.org
Review URL: https://codereview.chromium.org/22172002
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16049 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
I'm going to change CPU profiler API and deprecate GetSelfTime, GetTotalTime and GetTotalSamplesCount on CpuProfileNode as all of those values are derived from self samples count and sampling rate. The sampling rate in turn is calculate based on the profiling duration so having start/end time and total sample count is enough for calculating smpling rate.
BUG=267595
R=alph@chromium.org, bmeurer@chromium.org
Review URL: https://codereview.chromium.org/21918002
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16039 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Added instance method on v8::Isolate for retrieving instance of v8::HeapProfiler for that isolate. All static methods of v8::HeapProfiler are deprecated, corresponding instance methods are added to v8::HeapProfiler.
All static methods on v8::internal::HeapProfiler were converted into instance ones.
BUG=None
Review URL: https://codereview.chromium.org/12907006
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13997 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
CPU profiler API is extended with methods that allow to retrieve individual samples from profile. Each sample is presented as a pointer to a node in the top-down profile tree. The samples will let us tie JS performance to time.
BUG=None
Review URL: https://codereview.chromium.org/12919002
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13980 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Prevously v8 put a link to each context variable into a function where
the variable is visible.
Because of that if there are N functions sharing a context having M variables
then N*M links were created for the snapshot.
The fix makes v8 to put the links into the context object.
BUG=145687
TEST=test-heap-snapshot/ManyLocalsInSharedContext
Review URL: https://codereview.appspot.com/7715044
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13936 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
The stats data have only count field at the moment.
A constantly growing array of integers also can be a reason of a leak.
Ans we have to have a way to detect such kind of leaks.
Drive by fix:
FindObject and AddEntry were replaced with FindEntry/FindOrAddEntry pair.
BUG=none
TEST=HeapSnapshotObjectsStats
Review URL: https://chromiumcodereview.appspot.com/10086004
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@11327 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This patch changes the signature of the v8::HeapGraphNode::GetRetainedSize method, but it's not used in Chromium, and it should be easy for other clients (if any) to adjust to this change.
BUG=none
TEST=none
Review URL: https://chromiumcodereview.appspot.com/9466014
Patch from Alexei Filippov <alexeif@chromium.org>.
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10846 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
As example there are 'Detached DOM Tree' nodes in WebKit. It is very useful to be able to see all such
nodes grouped together. It can be done with help of some post processing but I did this explicitly
on v8 side because it is much faster. At the moment this kind of nodes has kNative type.
I'd like to hide these nodes from the Retainment View but I can filter them only by name.
BUG=none
TEST=HeapSnapshotRetainedObjectInfo
Review URL: https://chromiumcodereview.appspot.com/9323064
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10614 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
The detailed heap snapshot has two groups of nodes. The first one
is the group for v8 heap nodes and the second one is the group for
native objects. At the moment we have two different sets of native
objects. There are 'Detached DOM trees' and 'Document DOM trees' type of objects.
I think it'd be nice to replace one group containing all native objects with
separate groups for different types of native objects.
BUG=none
TEST=HeapSnapshotRetainedObjectInfo
Review URL: https://chromiumcodereview.appspot.com/9223009
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10528 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
As taking a snapshot of a large heap takes noticeable time, it's
good to be able to monitor and control it.
The change itself is small, big code deletes and additions are in
fact moves. The only significant change is simplification of
approximated retained sizes calculation algorithm.
Review URL: http://codereview.chromium.org/5687003
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5978 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Approximation is done by building a dominators tree for the heap graph.
Dominator nodes and retained sizes are serialized into JSON.
Removed:
- reachable size (it is useless, after all);
- HeapEntryCalculatedData (size is now stored in the node, retaining
paths in a hash map);
Review URL: http://codereview.chromium.org/5154007
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5867 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Otherwise, retaned memory sizes are not precise. This increases size
of heap snapshot, I will deal with this later. Heap objects and
references previously missing in snapshot are now marked as 'hidden'.
That means, they not shown to user, but participate in sizes
calculation.
Other small changes:
- added 'shortcut' graph edges: e.g. to pin global objects on top
level;
- meta-information in JSON snapshot is no more double encoded.
Review URL: http://codereview.chromium.org/5139002
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5849 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
HeapNumbers do consume memory, so it's worth dumping them. However, we
don't dump their values, as they are not as self-descriptive as values
of strings, and they will increase snapshot size. Storing heap numbers
values can be added if we will feel a sufficient demand for that.
InternalFields are used, e.g. for storing references to DOM nodes
event handlers.
Review URL: http://codereview.chromium.org/3769007
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5635 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
to avoid storing serialized snapshot on VM, instead it is emitted
using output stream interface.
The size of JSON emitted is roughly equal to used heap size
(when stored as an ASCII string).
Now a whole heap snapshot can be serialized and transmitted outside
VM. This makes possible:
- implementing non-async UI for heap snapshots inspection;
- storing heap snapshots for further inspection;
- remote profiling (we can even implement a snapshotting mode
where a snapshot isn't even stored in VM, only transmitted --
good for mobile devices);
- creating tools for outside heap snapshots processing, e.g.
converting to HPROF.
Review URL: http://codereview.chromium.org/3311028
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5450 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
To trace objects between snapshots, an external map of object tags is
maintained. After the first heap snapshot has been taken, the map is
updated by reporting object moves from the GC. If no snapshots were
taken, there is no overhead (except for flag checking).
I considered graph comparison algorithms that doesn't require using
object tags, but they are all of a high computational complexity, and
will still fail to detect object moves properly, even for trivial
cases, so using tags looks like unavoidable.
Review URL: http://codereview.chromium.org/3020002
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5078 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
As several pages can run in a single V8 instance, it is possible to
have functions from different security contexts intermixed in a single
CPU profile. To avoid exposing function names from one page to
another, filtering is introduced.
The basic idea is that instead of capturing return addresses from
stack, we're now capturing JSFunction addresses (as we anyway work
only with JS stack frames.) Each JSFunction can reach out for
context's security token. When providing a profile to a page, the
profile is filtered using the security token of caller page. Any
functions with different security tokens are filtered out (yes, we
only do fast path check for now) and their ticks are attributed to
their parents.
Review URL: http://codereview.chromium.org/2083005
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4673 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
