Make sweeper threads respect the max_available_threads constraint.

Make sweeper threads respect the max_available_threads constraint.

BUG=

Committed: https://crrev.com/3f5ff276f3d1837b92d1ced0b18253d3968c9c01
Cr-Commit-Position: refs/heads/master@{#27091}

[ulan, 2015-02-18 12:06:57]

ulan@chromium.org changed reviewers:
+ hpayer@chromium.org

[ulan, 2015-02-18 12:06:57]

PTAL

[Hannes Payer (out of office), 2015-02-19 17:32:56]

What is the motivation behind that cl? Note that concurrent sweeping turns into
lazy sweeping when no threads are available.

[ulan, 2015-02-20 09:57:37]

On 2015/02/19 17:32:56, Hannes Payer wrote:
> What is the motivation behind that cl? Note that concurrent sweeping turns
into
> lazy sweeping when no threads are available.

This is for embedders that run V8 in a single thread. Right now they have to
tweak flags which broke several times as flags changed.

max_available_threads is set from V8 API (ResourceConstraints), so we need to
respect this constraint anyway.

[Hannes Payer (out of office), 2015-02-20 11:53:33]

lgtm

[ulan, 2015-02-23 07:11:16]

The CQ bit was checked by ulan@chromium.org

[commit-bot: I haz the power, 2015-02-23 07:12:10]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/916103005/20001

[commit-bot: I haz the power, 2015-02-23 07:13:50]

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

[commit-bot: I haz the power, 2015-02-23 07:13:51]

Try jobs failed on following builders:
  v8_linux_nodcheck_rel on tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux_nodcheck_rel/build...)

[commit-bot: I haz the power, 2015-02-23 07:13:51]

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

[commit-bot: I haz the power, 2015-02-23 07:13:52]

Try jobs failed on following builders:
  v8_linux_nodcheck_rel on tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux_nodcheck_rel/build...)

[ulan, 2015-03-10 09:26:22]

The CQ bit was checked by ulan@chromium.org

[ulan, 2015-03-10 09:26:23]

The patchset sent to the CQ was uploaded after l-g-t-m from hpayer@chromium.org
Link to the patchset: https://codereview.chromium.org/916103005/#ps40001 (title:
"Fix compilation")

[commit-bot: I haz the power, 2015-03-10 09:29:10]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/916103005/40001

[commit-bot: I haz the power, 2015-03-10 09:58:22]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2015-03-10 09:58:41]

Patchset 3 (id:??) landed as
https://crrev.com/3f5ff276f3d1837b92d1ced0b18253d3968c9c01
Cr-Commit-Position: refs/heads/master@{#27091}