How to Deal with Android Size Alerts
Not all alerts should not have a bug created for them. Please read on...
Step 1: Identify the Commit
MonochromePublic.apk Alerts (Single Commit)
- Zoom in on the graph to make sure the alert is not off-by-one
- Replace
&num_points=XXXX
with &rev=COMMIT_POSITION
in the URL. - It will be obvious from this whether or not the point is off. Use the “nudge” feature to correct it when this happens.
MonochromePublic.apk Alerts (Multiple Commits or Rolls)
Example:
tools/binary_size/diagnose_bloat.py AFTER_GIT_REV --reference-rev BEFORE_GIT_REV --subrepo v8 --all
- You can usually find the before and after revs in the roll commit message (example)
- Note that you may need to click through the link for the list of changes in order to find the actual first commit hash and use that one instead since some rollers (including v8) use extra commits for tagging not in master. In the linked example
BEFORE_GIT_REV
would actually be 876f37c
and not c1dec05f
.
Monochrome.apk Alerts
- The regression most likely already occurred in the upstream MonochromePublic.apk target. Look at the graph of Monochrome.apk and MonochromePublic.apk overlaid to find the culprit and de-dupe with upstream alert.
- If no upstream regression was found, look through the downstream commits within the given date range to find the culprit.
- Via
git log --format=fuller
(be sure to look at CommitDate
and not AuthorDate
)
- If the culprit is not obvious, follow the steps from the “multiple commits” section above, filing a bug and running
diagnose_bloat.py
(with --subrepo=clank
).
Step 2: File Bug or Silence Alert
If the code clearly justifies the size increase, silence the alert.
Otherwise, file a bug (TODO: Make this template automatic):
- Change the bug's title from
X%
to XXkb
- Assign to commit author
- Set description to (replacing bold parts):
Caused by “First line of commit message”
Commit: abc123abc123abc123abc123abc123abc123abcd
Link to size graph: https://chromeperf.appspot.com/report?sid=bb23072657e2d7ca892a1c3fa4643b1ee29b3a0a44d0732adda87168e89c0380&num_points=10&rev=480214
Debugging size regressions is documented at: https://chromium.googlesource.com/chromium/src/+/master/docs/speed/apk_size_regressions.md#Debugging-Apk-Size-Increase
Based on the graph: 20kb of native code, 8kb of pngs.
Option 1:
It looks to me that the size increase is expected.
Feel free to close as “Won't Fix” unless you can see some way to reduce size.
Option 2:
It looks like this increase was probably unexpected or might be avoidable.
Please have a look and either:
- Close as “Won't Fix” with a short justification, or
- Land a revert / fix-up.
Option 3:
It's not clear to me whether or not this increase was expected.
Please have a look and either:
- Close as “Won't Fix” with a short justification, or
- Land a revert / fix-up.
Optional addition for commits > 75kb:
It typically takes about a week of engineering time to reduce binary size by 100kb so we'd really appreciate you taking some time exploring options to address this regression!
If you went with Option 2, and the regression is > 50kb, add ReleaseBlock-Stable M-6- (next branch cut).
Once the initial bug is filed, add a follow-up comment with the output of:
tools/binary_size/diagnose_bloat.py GIT_REV --cloud
Debugging Apk Size Increase
Step 1: Identify what Grew
Figure out which file within the .apk
increased (native library, dex, pak resources, etc) by looking at the breakdown in the size graphs linked to in the bug (if it was not linked in the bug, see above).
See //docs/speed/binary_size/metrics.md for a description of the metrics we track.
Step 2: Analyze
Growth is from Translations
- There is likely nothing that can be done. Translations are expensive.
- Close as
Won't Fix
.
Growth is from Native Resources (pak files)
Growth is from Images
Growth is from Native Code
- Use //tools/binary_size/diagnose_bloat.py to show a diff of ELF symbols.
- Googlers should use the speedy
--cloud
option. E.g.: tools/binary_size/diagnose_bloat.py 0f30c9488bd2bdc1db2749cd4683994a764a44c9 --cloud
- Paste the diff into the bug.
- If the diff looks reasonable, close as
Won't Fix
. - Otherwise, try to refactor a bit (e.g. move code out of templates).
- If symbols are larger than expected, use the
Disassemble()
feature of supersize console
to see what is going on.
Growth is from Java Code
Growth is from “other lib size” or “Unknown files size”
- File a bug against agrieve@ to fix resource_sizes.py.
- ...or fix it yourself. This script will output the list of unknown filenames.
You Would Like Assistance
For Binary Size Sheriffs
Step 1: Check work queue daily
- Bugs requiring sheriffs to take a look at are labeled
Performance-Sheriff
and Performance-Size
here. - After resolving the bug by finding an owner or debugging or commenting, remove the
Performance-Sheriff
label.
Step 2: Check alerts regularly
- IMPORTANT: Check the perf bot page several times a day to make sure it isn't broken (and ping/file a bug if it is).
- At the very least you need to check this once in the morning and once in the afternoon.
- If you don't and the builder is broken either you or the next sheriff will have to manually build and diff the broken range (via. diagnose_bloat.py) to see if we missed any regressions.
- This is necessary even if the next passing build doesn't create an alert because the range could contain a large regression with multiple offsetting decreases.
- Check alert page regularly for new alerts.
- Join binary-size-alerts@chromium.org. Eventually it will be all set up.
- Deal with alerts as outlined above.