[tools] Manually write JSON in profile.js to avoid huge strings

[tools] Manually write JSON in profile.js to avoid huge strings

In the tick processor, in cases where there are a lot of ticks (e.g.
long running programs), JSON.stringify could throw a range exception
because the created string is too large.

Instead of creating the entire JSON string in memory, we now write the
top-level parts of the JSON manually, writing out the ticks individually
instead of all together.

Review-Url: https://codereview.chromium.org/2754683002
Cr-Commit-Position: refs/heads/master@{#43973}
Committed: https://chromium.googlesource.com/v8/v8/+/0956e587928c7ad8fa4049791a7015cc91bbea53

[Leszek Swirski, 2017-03-15 16:16:03]

The CQ bit was checked by leszeks@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2017-03-15 16:16:07]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[Leszek Swirski, 2017-03-15 16:22:33]

leszeks@chromium.org changed reviewers:
+ jarin@chromium.org

[Leszek Swirski, 2017-03-15 16:22:33]

Hi Jaro,
Small fix to profile.js to fix an issue I had with profiles of longer runs.
WDYT?

[commit-bot: I haz the power, 2017-03-15 16:39:09]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2017-03-15 16:39:10]

Dry run: This issue passed the CQ dry run.

[Jarin, 2017-03-16 05:42:32]

On 2017/03/15 16:22:33, Leszek Swirski wrote:
> Hi Jaro,
> Small fix to profile.js to fix an issue I had with profiles of longer runs.
> WDYT?

With your fix, are you still able to read the Json in the browser? I would
expect that if we are not able to create the string on the producer side, we are
unlikely to be able to consume it.

[Leszek Swirski, 2017-03-16 10:34:13]

On 2017/03/16 05:42:32, Jarin wrote:
> On 2017/03/15 16:22:33, Leszek Swirski wrote:
> > Hi Jaro,
> > Small fix to profile.js to fix an issue I had with profiles of longer runs.
> > WDYT?
> 
> With your fix, are you still able to read the Json in the browser? I would
> expect that if we are not able to create the string on the producer side, we
are
> unlikely to be able to consume it.

Not in the browser, since the consumer is also V8. However, I've also been using
command-line JSON parsing tools (e.g. jq) to aggregate data, and those handle
larger files fine (if slowly).

[Jarin, 2017-03-20 20:57:16]

lgtm

[Leszek Swirski, 2017-03-21 10:31:44]

The CQ bit was checked by leszeks@chromium.org

[commit-bot: I haz the power, 2017-03-21 10:31:54]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-03-21 10:58:27]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1490092304102670, "parent_rev":
"c0c55250f2eff603cc587e0f557d0aba55210bc2", "commit_rev":
"0956e587928c7ad8fa4049791a7015cc91bbea53"}

[commit-bot: I haz the power, 2017-03-21 10:58:31]

Description was changed from

==========
[tools] Manually write JSON in profile.js to avoid huge strings

In the tick processor, in cases where there are a lot of ticks (e.g.
long running programs), JSON.stringify could throw a range exception
because the created string is too large.

Instead of creating the entire JSON string in memory, we now write the
top-level parts of the JSON manually, writing out the ticks individually
instead of all together.
==========

to

==========
[tools] Manually write JSON in profile.js to avoid huge strings

In the tick processor, in cases where there are a lot of ticks (e.g.
long running programs), JSON.stringify could throw a range exception
because the created string is too large.

Instead of creating the entire JSON string in memory, we now write the
top-level parts of the JSON manually, writing out the ticks individually
instead of all together.

Review-Url: https://codereview.chromium.org/2754683002
Cr-Commit-Position: refs/heads/master@{#43973}
Committed:
https://chromium.googlesource.com/v8/v8/+/0956e587928c7ad8fa4049791a7015cc91b...
==========

[commit-bot: I haz the power, 2017-03-21 10:58:32]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/v8/v8/+/0956e587928c7ad8fa4049791a7015cc91b...