Issue 2676003002: Use TaskScheduler instead of blocking pool in chrome_browser_main_chromeos.cc.

fdoray

Hi! I'm a Python script responsible for migrating tasks from the blocking pool to TaskScheduler. ...

3 years, 10 months ago (2017-02-03 17:18:43 UTC) #1

Hi! I'm a Python script responsible for migrating tasks from the
blocking pool to TaskScheduler. In this CL, I used these traits to post to
TaskScheduler a task that was previously posted to the blocking pool:

.WithPriority(base::TaskPriority::BACKGROUND)
  User won't notice if the task takes an arbitrarily long time to complete.
  Making your task BACKGROUND allows non-BACKGROUND tasks to run faster :)

*No* .WithShutdownBehavior()

.MayBlock()
  The task may block. This includes but is not limited to tasks that wait on
  synchronous file I/O operations: read or write a file from disk, interact
  with a pipe or a socket, rename or delete a file, enumerate files in a
  directory, etc. This trait isn't required for the mere use of locks.

*No* .WithBaseSyncPrimitives()
  The task is not allowed to use these functions:
  - base::WaitableEvent::Wait
  - base::ConditionVariable::Wait
  - base::PlatformThread::Join
  - base::PlatformThread::Sleep
  - base::Process::WaitForExit
  - base::Process::WaitForExitWithTimeout

If you think this is correct, please LGTM and CQ this CL.

Otherwise, tell me which traits I should have used and I'll automatically
upload a new patch. You can find documentation at
https://cs.chromium.org/chromium/src/base/task_scheduler/task_traits.h

WithPriority()
[default/BACKGROUND/USER_VISIBLE/USER_BLOCKING]:

WithShutdownBehavior()
[default/CONTINUE_ON_SHUTDOWN/SKIP_ON_SHUTDOWN/BLOCK_SHUTDOWN]:

MayBlock()
[yes/no]:

WithBaseSyncPrimitives()
[yes/no]:

Comments for a human:
[A human will read this]

FAQ:

What should I do if the CQ dry run didn't pass?
You can ignore this CL. A human will take a look and get back to you.

Why are you doing this?
Browser threads, the blocking pool and base::WorkerPool are being deprecated
in favor of TaskScheduler. Design doc:
https://docs.google.com/document/d/1S2AAeoo1xa_vsLbDYBsDHCqhrkfiMgoIPlyRi6kxa...

What is the default priority?
A task posted to TaskScheduler without an explicit priority inherits its
priority from the calling context (e.g. a task posted to TaskScheduler
from a BACKGROUND task without an explicit .WithPriority() will have a
BACKGROUND priority).

What is the default shutdown behavior?
It is not documented on purpose. If your task shouldn't be skipped on shutdown
(e.g. a task that persists user data on disk), it should have an explicit
BLOCK_SHUTDOWN shutdown behavior. If it's important not to wait on your task
on shutdown (e.g. it takes a long time to run and could cause a shutdown
hang), it should have an explicit CONTINUE_ON_SHUTDOWN shutdown behavior.

fdoray

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

3 years, 10 months ago (2017-02-03 17:18:44 UTC) #2