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
