Add DVLOG with child process id in mojo shell.

Add DVLOG with child process id in mojo shell.

When running "./chrome --mash" most child processes no longer have the
mojo application name as part of the command string. This makes it
difficult to figure out what part of mus+ash LOG statements or CHECK
failures come from. Add a DVLOG(0) that prints out the name and pid when
a child process is successfully launched.

Using verbosity level 0 since it is important information for debugging
and should occur rarely.

BUG=none

Committed: https://crrev.com/97d674fed83626047e8cda9305c488a12a4ab3cf
Cr-Commit-Position: refs/heads/master@{#408717}

[kylechar, 2016-07-29 17:42:05]

kylechar@chromium.org changed reviewers:
+ jam@chromium.org, rockot@chromium.org

[kylechar, 2016-07-29 17:42:06]

Not totally sure who to send this to but let me know what you think? Some sort
of DLOG with the pid of child processes seems super useful to me.

It's a bit frustrating trying to figure out what process LOG and CHECK
statements come from when debugging mus+ash code. Especially when top shows
something like this:

22484 /usr/local/google/data/chrome/src/out_ozone/chrome --mash
--mojo-platform-channel-handle=3
--primordial-pipe-token=0AC5D938D61B67EF2D1B87FD1C5E0EAF --type=mash-child
22489 /usr/local/google/data/chrome/src/out_ozone/chrome --mash
--mojo-platform-channel-handle=3
--primordial-pipe-token=3610E6E5C85921ACCAEB31A1E8FC1682 --type=mash-child
22490 /usr/local/google/data/chrome/src/out_ozone/chrome --mash
--mojo-platform-channel-handle=3
--primordial-pipe-token=558F2BFA397E0BC380A234B9365CD07F --type=mash-child
22491 /usr/local/google/data/chrome/src/out_ozone/chrome --mash
--mojo-platform-channel-handle=3
--primordial-pipe-token=4ED65194ADD1705C58CE01FC011843D1 --type=mash-child
22492 /usr/local/google/data/chrome/src/out_ozone/chrome --mash
--mojo-platform-channel-handle=3
--primordial-pipe-token=0807139D8F027734055434679CB6C5F0 --type=mash-child
22496 /usr/local/google/data/chrome/src/out_ozone/chrome --mash
--mojo-platform-channel-handle=3
--primordial-pipe-token=1F9E8E469885CC5F17C7D1028138CDA7 --type=mash-child
22500 /usr/local/google/data/chrome/src/out_ozone/chrome --mash
--mojo-platform-channel-handle=3
--primordial-pipe-token=9F02933C8FA8609F2FC23206CABEA470 --type=mash-child

DVLOG(1) seems to print a message for every single IPC message sent, so I used
DVLOG(0) to avoid the mess of spam.

[Ken Rockot(use gerrit already), 2016-07-29 17:48:00]

lgtm

https://codereview.chromium.org/2194943002/diff/1/services/shell/runner/host/...
File services/shell/runner/host/child_process_host.cc (right):

https://codereview.chromium.org/2194943002/diff/1/services/shell/runner/host/...
services/shell/runner/host/child_process_host.cc:202: DVLOG(0) << "Launched
child process '" << target_.instance()
I think this is a reasonable thing to do. You may want to log more than just the
instance though. Might as well log name, user_id, and instance?

[kylechar, 2016-07-29 17:59:34]

Thanks!

https://codereview.chromium.org/2194943002/diff/1/services/shell/runner/host/...
File services/shell/runner/host/child_process_host.cc (right):

https://codereview.chromium.org/2194943002/diff/1/services/shell/runner/host/...
services/shell/runner/host/child_process_host.cc:202: DVLOG(0) << "Launched
child process '" << target_.instance()
On 2016/07/29 17:48:00, Ken Rockot wrote:
> I think this is a reasonable thing to do. You may want to log more than just
the
> instance though. Might as well log name, user_id, and instance?

Yep, they could definitely come in handy. I added the extra fields.

[kylechar, 2016-07-29 18:17:18]

The CQ bit was checked by kylechar@chromium.org

[kylechar, 2016-07-29 18:17:19]

The patchset sent to the CQ was uploaded after l-g-t-m from rockot@chromium.org
Link to the patchset: https://codereview.chromium.org/2194943002/#ps20001
(title: "Include name and user_id.")

[commit-bot: I haz the power, 2016-07-29 18:17:47]

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, 2016-07-29 19:21:59]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-07-29 19:25:28]

Description was changed from

==========
Add DVLOG with child process id in mojo shell.

When running "./chrome --mash" most child processes no longer have the
mojo application name as part of the command string. This makes it
difficult to figure out what part of mus+ash LOG statements or CHECK
failures come from. Add a DVLOG(0) that prints out the name and pid when
a child process is successfully launched.

Using verbosity level 0 since it is important information for debugging
and should occur rarely.

BUG=none
==========

to

==========
Add DVLOG with child process id in mojo shell.

When running "./chrome --mash" most child processes no longer have the
mojo application name as part of the command string. This makes it
difficult to figure out what part of mus+ash LOG statements or CHECK
failures come from. Add a DVLOG(0) that prints out the name and pid when
a child process is successfully launched.

Using verbosity level 0 since it is important information for debugging
and should occur rarely.

BUG=none

Committed: https://crrev.com/97d674fed83626047e8cda9305c488a12a4ab3cf
Cr-Commit-Position: refs/heads/master@{#408717}
==========

[commit-bot: I haz the power, 2016-07-29 19:25:29]

Patchset 2 (id:??) landed as
https://crrev.com/97d674fed83626047e8cda9305c488a12a4ab3cf
Cr-Commit-Position: refs/heads/master@{#408717}