DevTools: speed up DevToolsUIBindings::DispatchProtocolMessage

DevTools: speed up DevToolsUIBindings::DispatchProtocolMessage

Old implementation cost us 11s of cpu time per 442Mb of messages.

BUG=

Committed: https://crrev.com/df966200b2f301e63e1cfe4124753dcbc7571af3
Cr-Commit-Position: refs/heads/master@{#309164}

[loislo, 2014-12-05 12:45:46]

loislo@chromium.org changed reviewers:
+ dgozman@chromium.org, pfeldman@chromium.org, yurys@chromium.org

[yurys, 2014-12-05 13:03:30]

https://codereview.chromium.org/784513002/diff/1/chrome/browser/devtools/devt...
File chrome/browser/devtools/devtools_ui_bindings.cc (right):

https://codereview.chromium.org/784513002/diff/1/chrome/browser/devtools/devt...
chrome/browser/devtools/devtools_ui_bindings.cc:453:
"DevToolsAPI.dispatchMessage(" + message + ");");
Content shell implementation should also be updated.

[dgozman, 2014-12-05 13:04:05]

Please change shell_devtools_frontend as well, so tests are identical to
production.

Btw, did you measure the speed-up?

[loislo, 2014-12-05 13:11:04]

On 2014/12/05 13:04:05, dgozman wrote:
> Please change shell_devtools_frontend as well, so tests are identical to
> production.
> 
> Btw, did you measure the speed-up?


I've seen only 20% cpu on browser process vs 100% before the patch.

[loislo, 2014-12-05 13:11:26]

https://codereview.chromium.org/784513002/diff/1/chrome/browser/devtools/devt...
File chrome/browser/devtools/devtools_ui_bindings.cc (right):

https://codereview.chromium.org/784513002/diff/1/chrome/browser/devtools/devt...
chrome/browser/devtools/devtools_ui_bindings.cc:453:
"DevToolsAPI.dispatchMessage(" + message + ");");
On 2014/12/05 13:03:30, yurys wrote:
> Content shell implementation should also be updated.

Done.

[pfeldman, 2014-12-12 12:27:01]

But this does not help us - large messages are still double-escaped while small
ones are not.

[loislo, 2014-12-13 19:33:38]

On 2014/12/12 12:27:01, pfeldman wrote:
> But this does not help us - large messages are still double-escaped while
small
> ones are not.

This patch definitely improves the speed for normal messages
and we can keep the size of messages under control in many cases.
For example I prepared a patch which fixes the problem with large
tracing messages. https://codereview.chromium.org/750183008/

Heap profiler has no problem with the message sizes but unfortunately it avoids
that by manual escaping.

BTW It would be interesting to collect stats about commands that were chunked
and their sizes.

[pfeldman, 2014-12-18 15:25:53]

lgtm

[loislo, 2014-12-19 06:24:33]

The CQ bit was checked by loislo@chromium.org

[commit-bot: I haz the power, 2014-12-19 06:24:55]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/784513002/20001

[commit-bot: I haz the power, 2014-12-19 07:51:47]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2014-12-19 07:52:37]

Patchset 2 (id:??) landed as
https://crrev.com/df966200b2f301e63e1cfe4124753dcbc7571af3
Cr-Commit-Position: refs/heads/master@{#309164}