/var/log/ui vs /var/log/chrome

[Adrian Elder]

Does /var/log/chrome/chrome contain a superset of things from /var/log/ui/ui.LATEST?

Is there a doc where I can learn more about the differences between these two logs?

I came this question by noting that lines like the following are logged in /var/log/chrome but not in /var/log/ui. On a Non-ChromeOS Linux Device, I see these in chrome_debug.log.

[1:6331:1218/122249.888257:WARNING:media_stream_audio_processor.cc(856)] Large audio delay, capture delay: 424ms; render delay: 0ms

[Daniel Erat]

I could've sworn that this was documented somewhere, but I'm not having any luck finding it now. I've written a quick doc that's up for review at https://crrev.com/c/837587. Here's the relevant bit (in markdown):

---

Messages written via the logging macros in [base/logging.h] end up in different

locations depending on Chrome's state:

* `/var/log/ui/ui.LATEST` contains data written to stdout and stderr by Chrome.

  This generally comprises messages that are written very early in Chrome's

  startup process, before logging has been initialized.

* `/var/log/chrome/chrome` contains messages that are written at the login

  screen before a user has logged in.

* `/home/chronos/user/log/chrome` contains messages that are written while a

  user is logged in. Note that this path is within the user's encrypted home

  directory and is only accessible while the user is logged in.

All of the above files are actually symlinks. Older log files can be found

alongside them in the same directories.

Also notable is `/var/log/messages`. This file contains general syslog messages,

but it also includes messages written by `session_manager` that may be useful in

determining when or why Chrome started or stopped.

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[Adrian Elder]

Thanks for updating the docs!

I'm only a little confused by this description of /var/log/chrome/chrome. Looking at logs on an enterprise managed device running with a robot account (a Chromebox for Meetings device) I see lots of logging activity in /var/log/chrome/chrome after the robot account has logged in.

[Daniel Erat]

Hmm, I'm not sure about that. I think that the relevant code for switching log files is at chrome/browser/chromeos/logging.cc.

[Adrian Elder]

Looking at the code, I don't see any way that it could have, but is there any way that kDisableLoggingRedirect is enabled for test images by default? I'm looking at a device running a test image.

[Luigi Semenzato]

No, that's not it. The test images log in
/home/chronos/user/log/chrome when someone is logged on.

[Daniel Erat]

Are you seeing this while Autotest-based tests are running (or after running a test)? Telemetry/Catapult uses --disable-logging-redirect when it restarts Chrome.

(ps should tell you whether the flag is present.)

[Adrian Elder]

No autotest. Running ChromeOS 9901.77.0 / Chrome 62.0.3202.97 on a buddy.

Flags from ps:

/opt/google/chrome/chrome

  --ppapi-flash-path=/opt/google/chrome/pepper/libpepflashplayer.so

  --ppapi-flash-version=27.0.0.187

  --ui-prioritize-in-gpu-process

  --use-gl=egl

  --enable-native-gpu-memory-buffers

  --gpu-sandbox-failures-fatal=yes

  --enable-logging

  --log-level=1

  --use-cras

  --enable-wayland-server

  --user-data-dir=/home/chronos

  --max-unused-resource-memory-usage-percentage=5

  --system-developer-mode

  --disable-lock-screen-apps

  --login-profile=user

  --has-chromeos-keyboard

  --default-wallpaper-large=/usr/share/chromeos-assets/wallpaper/oem_large.jpg

  --default-wallpaper-small=/usr/share/chromeos-assets/wallpaper/oem_small.jpg

  --default-wallpaper-is-oem

  --guest-wallpaper-large=/usr/share/chromeos-assets/wallpaper/guest_large.jpg

  --guest-wallpaper-small=/usr/share/chromeos-assets/wallpaper/guest_small.jpg

  --enable-consumer-kiosk

  --enterprise-enrollment-initial-modulus=15

  --enterprise-enrollment-modulus-limit=19

  --login-manager

  --first-exec-after-boot

  --vmodule=tablet_power_button_controller=1,*chromeos/login/*=1,auto_enrollment_controller=1,*plugin*=2,*zygote*=1,*/ui/ozone/*=1,*/ui/display/manager/chromeos/*=1,power_button_observer=2,webui_login_view=2,lock_state_controller=2,webui_screen_locker=2,screen_locker=2

[David Riley]

I'll jump on this thread to plug the merge_logs script (https://chromium.googlesource.com/chromiumos/chromite/+/master/scripts/merge_logs.py) which should combine logs in chronological order from multiple files for a single view, handling most/all the different date formats used in the various log files.

(Resent from correct email address for list.)