[d8 Workers] Add max worker count, throw an exception if too many.

[d8 Workers] Add max worker count, throw an exception if too many.

BUG=chromium:518748
R=mstarzinger@chromium.org
LOG=n

Committed: https://crrev.com/29e441422e288eac16d8ffd8caf7e56e8ed77638
Cr-Commit-Position: refs/heads/master@{#30230}

[Michael Starzinger, 2015-08-10 22:01:24]

https://codereview.chromium.org/1284683004/diff/1/test/mjsunit/regress/regres...
File test/mjsunit/regress/regress-crbug-518748.js (right):

https://codereview.chromium.org/1284683004/diff/1/test/mjsunit/regress/regres...
test/mjsunit/regress/regress-crbug-518748.js:8: for (var i = 0; new
Worker('onmessage = function() {};'); i++) a[i] = i;
The regression test is kind of brittle, because if the workers finish fast
enough, there will never be more than 100 of them running in parallel. We need
some more reliable way to test that. Also a loop that doesn't run infinitely but
is bounded somehow would be better.

[binji, 2015-08-10 22:09:47]

https://codereview.chromium.org/1284683004/diff/1/test/mjsunit/regress/regres...
File test/mjsunit/regress/regress-crbug-518748.js (right):

https://codereview.chromium.org/1284683004/diff/1/test/mjsunit/regress/regres...
test/mjsunit/regress/regress-crbug-518748.js:8: for (var i = 0; new
Worker('onmessage = function() {};'); i++) a[i] = i;
On 2015/08/10 at 22:01:23, Michael Starzinger wrote:
> The regression test is kind of brittle, because if the workers finish fast
enough, there will never be more than 100 of them running in parallel. We need
some more reliable way to test that. Also a loop that doesn't run infinitely but
is bounded somehow would be better.

Workers are not reaped until the main thread is finished, so this should not be
a problem. But if someone decided to fix that, you're right. In any case, there
needs to be a better test because this is failing on multiple bots as-is. :)

[Michael Starzinger, 2015-08-10 22:14:41]

LGTM on the limit in d8.cc, just a reliable test case is needed.

https://codereview.chromium.org/1284683004/diff/1/test/mjsunit/regress/regres...
File test/mjsunit/regress/regress-crbug-518748.js (right):

https://codereview.chromium.org/1284683004/diff/1/test/mjsunit/regress/regres...
test/mjsunit/regress/regress-crbug-518748.js:8: for (var i = 0; new
Worker('onmessage = function() {};'); i++) a[i] = i;
On 2015/08/10 22:09:47, binji wrote:
> On 2015/08/10 at 22:01:23, Michael Starzinger wrote:
> > The regression test is kind of brittle, because if the workers finish fast
> enough, there will never be more than 100 of them running in parallel. We need
> some more reliable way to test that. Also a loop that doesn't run infinitely
but
> is bounded somehow would be better.
> 
> Workers are not reaped until the main thread is finished, so this should not
be
> a problem. But if someone decided to fix that, you're right. In any case,
there
> needs to be a better test because this is failing on multiple bots as-is. :)

Ah, got it. My bad, I was assuming the {workers} list in d8.cc would be emptied
out whenever a worker terminated. But yes, as you mentioned, for some reason
some try-bots still fail on this test, so it's brittle for other reasons.

[binji, 2015-08-18 16:46:48]

The CQ bit was checked by binji@chromium.org

[binji, 2015-08-18 16:46:49]

The patchset sent to the CQ was uploaded after l-g-t-m from
mstarzinger@chromium.org
Link to the patchset: https://codereview.chromium.org/1284683004/#ps20001
(title: "decrease worker limit")

[commit-bot: I haz the power, 2015-08-18 16:47:02]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1284683004/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1284683004/20001

[commit-bot: I haz the power, 2015-08-18 17:12:09]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-08-18 17:12:24]

Patchset 2 (id:??) landed as
https://crrev.com/29e441422e288eac16d8ffd8caf7e56e8ed77638
Cr-Commit-Position: refs/heads/master@{#30230}