Merge branch 'main' into fix-signatures-test-teardown-race
This commit is contained in:
Jason Ross
@@ -314,8 +314,23 @@ jobs:
|
||||
name: E2E (API 37 preview)
|
||||
runs-on: ubuntu-latest
|
||||
timeout-minutes: 35
|
||||
# Sharded N=2 (docs/perf/api37-e2e-sharding-spike.md). The instrumented suite is split across
|
||||
# 2 parallel API 37 emulators — each a separate matrix leg that hand-provisions its OWN emulator
|
||||
# and runs one shard via AndroidJUnitRunner's numShards/shardIndex. This leg is the pipeline's
|
||||
# critical path, so sharding cuts it ~17.1 min -> ~12.7 min (~28% off total CI) for +1 emulator
|
||||
# job. FAN-IN: `ci-passed` lists `e2e-preview` once and GHA rolls BOTH shard legs under that one
|
||||
# entry — a matrix job's aggregate result is `failure` if ANY leg fails — so both shards must
|
||||
# pass, and branch protection (which requires the "CI passed" context, not the per-leg
|
||||
# "E2E (API 37 preview) (N)" names) needs no change. `fail-fast: false` lets one shard's failure
|
||||
# NOT cancel the other, so both reports always upload. Keep API37_NUM_SHARDS in lockstep with the
|
||||
# length of matrix.shard.
|
||||
strategy:
|
||||
fail-fast: false
|
||||
matrix:
|
||||
shard: [0, 1] # 0-based shardIndex values; length must equal API37_NUM_SHARDS below
|
||||
env:
|
||||
API37_IMAGE: "system-images;android-37.0;google_apis_ps16k;x86_64"
|
||||
API37_NUM_SHARDS: "2"
|
||||
steps:
|
||||
- name: Check out source
|
||||
uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
|
||||
@@ -427,12 +442,31 @@ jobs:
|
||||
return 1
|
||||
}
|
||||
|
||||
# Start the adb daemon up-front (mirrors api37_e2e.py wait_for_boot) so attempt 1 can't
|
||||
# lose the adb-server "Address already in use" bind race that flaked #370's boot.
|
||||
adb start-server || true
|
||||
|
||||
booted=0
|
||||
for attempt in 1 2; do boot_emulator "$attempt" && { booted=1; break; }; done
|
||||
[ "$booted" = "1" ] || { echo "::error::API 37 preview emulator failed to boot after 2 attempts"; exit 1; }
|
||||
|
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adb shell input keyevent 82 || true
|
||||
./gradlew connectedDebugAndroidTest --stacktrace
|
||||
# Run only this matrix leg's shard. AndroidJUnitRunner hashes each test name into one of
|
||||
# numShards buckets and runs only shardIndex's bucket. The args flow through AGP's
|
||||
# -Pandroid.testInstrumentationRunnerArguments.* channel (the same one local_instrumented.py
|
||||
# uses for .class=…) — no GMD, no orchestrator, no Gradle-side change.
|
||||
run_shard() {
|
||||
./gradlew connectedDebugAndroidTest --stacktrace \
|
||||
"-Pandroid.testInstrumentationRunnerArguments.numShards=${API37_NUM_SHARDS}" \
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||||
"-Pandroid.testInstrumentationRunnerArguments.shardIndex=${{ matrix.shard }}"
|
||||
}
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||||
# Retry this shard's test run ONCE on failure — retry parity with the stable `e2e` matrix
|
||||
# (which retries once, so a flaky test self-heals on API 29–36 but would otherwise wedge
|
||||
# the required gate on API 37, e.g. #370). Per-shard, so the retry re-runs only this shard's
|
||||
# ~T/N tests, not the whole suite. MITIGATION, NOT A FIX: a blanket retry also masks genuine
|
||||
# regressions, so the retried-but-passed case is flagged as a ::warning:: and the real fix
|
||||
# stays test-level. See docs/perf/api37-e2e-sharding-spike.md.
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||||
run_shard || { echo "::warning::API 37 shard ${{ matrix.shard }} test run failed — retrying once"; run_shard; }
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||||
|
||||
- name: Dump emulator log on failure
|
||||
if: failure()
|
||||
@@ -446,7 +480,8 @@ jobs:
|
||||
if: always()
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||||
uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
|
||||
with:
|
||||
name: e2e-api37-boot-diagnostics
|
||||
# Shard-unique name — upload-artifact@v7 errors on duplicate artifact names.
|
||||
name: e2e-api37-boot-diagnostics-shard${{ matrix.shard }}
|
||||
path: |
|
||||
${{ runner.temp }}/emulator.log
|
||||
${{ runner.temp }}/logcat.txt
|
||||
@@ -461,7 +496,8 @@ jobs:
|
||||
if: ${{ !cancelled() }}
|
||||
uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
|
||||
with:
|
||||
name: e2e-test-report-api37-preview
|
||||
# Shard-unique name — upload-artifact@v7 errors on duplicate artifact names.
|
||||
name: e2e-test-report-api37-preview-shard${{ matrix.shard }}
|
||||
path: app/build/reports/androidTests/connected/
|
||||
if-no-files-found: warn
|
||||
|
||||
|
||||
@@ -0,0 +1,288 @@
|
||||
<!-- SPDX-License-Identifier: GPL-3.0-or-later -->
|
||||
# API 37 preview E2E sharding — adopted at N=2
|
||||
|
||||
**Status: ADOPTED (N=2).** `e2e-preview` is sharded across 2 parallel API 37 emulators in
|
||||
`.github/workflows/ci.yml`. This document is the design + measurement record behind that change: it
|
||||
began as a time-boxed feasibility spike (should we shard the hand-provisioned API 37 /
|
||||
`google_apis_ps16k` 16 KB-page emulator that ran the whole instrumented suite serially?) and now
|
||||
records the adopted design. `e2e-preview` was **consistently the single longest leg in CI**
|
||||
(~16.4–17.6 min on recent runs), so it set the pipeline's critical path.
|
||||
|
||||
The analysis below was produced from CI run logs and repo config only — **no emulator was booted
|
||||
locally** (avoids the machine-freeze risk noted in the project memory and runner contention). All
|
||||
numbers come from real successful `e2e-preview` runs; the PR's own CI run validates the live 2-shard
|
||||
timings and that both shards gate `ci-passed`.
|
||||
|
||||
## TL;DR / recommendation
|
||||
|
||||
**ADOPTED — `e2e-preview` is sharded in CI at `N = 2`** (a `strategy.matrix.shard: [0, 1]` fan-out —
|
||||
the values are **0-based** `shardIndex`es — each shard provisioning its own API 37 emulator and running
|
||||
one half of the suite via AndroidJUnitRunner's built-in `numShards`/`shardIndex`). Projected: the leg
|
||||
drops from **~17.1 min → ~12.7 min**, cutting the whole pipeline's critical path by **~4.9 min (~28%)**
|
||||
for the cost of **+1 emulator job (~1.5× this leg's emulator-minutes)**. Two reliability fixes ship with
|
||||
it: per-shard **test-retry parity** with the stable `e2e` matrix and an **`adb start-server`** before the
|
||||
boot loop (§5.9 / §6).
|
||||
|
||||
- **`N = 3` is a defensible stretch** (~11.2 min) but buys only ~0.7 min more of *total-CI* time, because
|
||||
at that point the **rest of the E2E matrix (API 30, ~12.0 min) becomes the new critical path**. The
|
||||
extra 0.7 min costs a second added emulator and +50% more preview-boot flake surface.
|
||||
- **Do NOT exceed `N = 3`.** Below ~12 min the API 29–36 matrix caps the pipeline; further API 37 shards
|
||||
burn emulator-minutes for zero wall-clock gain.
|
||||
- **Keep local preflight single-emulator.** `api37_e2e.py` / `local_instrumented.py` must stay one cold
|
||||
boot — a dev box has one free hypervisor (VT-x/WHPX) and the project memory explicitly warns parallel
|
||||
emulators can freeze the machine. Sharding is a **CI-only** change.
|
||||
- The mechanism is already proven in-repo: `local_instrumented.py` passes
|
||||
`-Pandroid.testInstrumentationRunnerArguments.class=…` to the same `connectedDebugAndroidTest` task,
|
||||
so `numShards`/`shardIndex` args flow the identical way — **no GMD, no orchestrator, no Gradle change**.
|
||||
|
||||
## 1. Current job anatomy + timing breakdown
|
||||
|
||||
`e2e-preview` (`.github/workflows/ci.yml`) hand-provisions the emulator because API 37's only image is the
|
||||
nonstandard `system-images;android-37.0;google_apis_ps16k;x86_64` (16 KB page size), which neither
|
||||
`reactivecircus/android-emulator-runner` nor AGP's Gradle Managed Device DSL can build. It installs the
|
||||
SDK + image directly (`sdkmanager`), creates the AVD (`avdmanager`), cold-boots headless with a
|
||||
two-attempt retry loop, then runs `./gradlew connectedDebugAndroidTest`. `api37_e2e.py` mirrors this
|
||||
locally (identical image/flags except `-gpu auto-no-window` vs CI's `-gpu swiftshader_indirect`).
|
||||
|
||||
### Step timing — reference run `28811804353` (branch `fix-359-sqlcipher-16kb`, **success**, total **17.6 min**)
|
||||
|
||||
| Phase | Step(s) | Time | Re-paid per shard? |
|
||||
|-------|---------|-----:|:------------------:|
|
||||
| Job/checkout/JDK/Gradle/KVM setup | 1–6 | ~0.4 min | yes |
|
||||
| Restore image cache + `sdkmanager` install (cache **hit**) | 7–8 | ~0.7 min | yes |
|
||||
| `avdmanager create avd` | 9 | ~0.03 min | yes |
|
||||
| **Emulator cold boot** (1 failed attempt + retry) | 10a | **~1.1 min** | yes |
|
||||
| **Gradle daemon start + configure + dependency resolution** | 10b | **~4.1 min** | yes |
|
||||
| **Compile debug app + androidTest APK + install** | 10c | **~2.0 min** | yes (per runner) |
|
||||
| **Test execution** (`Starting 263 tests` → `Finished 263 tests`) | 10d | **~8.75 min** | **NO — parallelizable** |
|
||||
| Teardown, upload report/diagnostics, post-cache/gradle | 12–29 | ~0.4 min | yes |
|
||||
|
||||
Step 10 ("Boot emulator and run E2E", 16.05 min) bundles boot + build + test into one shell step; the
|
||||
sub-splits above were recovered from the step's own timestamped log markers
|
||||
(`##[group]Start API 37 emulator`, `Starting N tests on emulator-5554`, `Finished N tests`, `BUILD SUCCESSFUL`).
|
||||
|
||||
### The boot-vs-test ratio (the crux)
|
||||
|
||||
Sharding only parallelizes **test execution**; every shard re-pays boot **and** the whole fixed prologue
|
||||
(setup + boot + Gradle daemon/config + compile + install + teardown). The fixed cost is **not just boot**
|
||||
(~1.1 min) — it is dominated by the ~6 min Gradle daemon-start/configure/compile block. Splitting the job:
|
||||
|
||||
- **`T` (parallelizable test execution) ≈ 8.8 min**
|
||||
- **`B` (fixed, re-paid by every shard) ≈ 8.3 min**
|
||||
|
||||
i.e. **B ≈ T** — roughly a 50/50 split. That is the single most important number in this analysis: because
|
||||
the fixed overhead is about as large as the test time, sharding has a **hard floor of ~8.3 min** no matter
|
||||
how many shards you add.
|
||||
|
||||
### Cross-run confirmation (test execution is stable, not a one-off)
|
||||
|
||||
| Run | Branch | Total leg | Test-exec window | Boot attempts |
|
||||
|-----|--------|----------:|-----------------:|:-------------:|
|
||||
| `28811804353` | fix-359-sqlcipher-16kb | 17.6 min | ~8.75 min (263 tests) | 2 |
|
||||
| `28763651551` | feat-125-imap-connection-reuse | 16.9 min | ~9.2 min (262 tests) | 1 |
|
||||
| `28760208017` | fix-359-sqlcipher-16kb | 16.4 min | ~8.4 min (261 tests) | 2 |
|
||||
|
||||
Test execution is a tight **8.4–9.2 min**; the leg total **16.4–17.6 min**. Run-to-run variance (~±0.6 min)
|
||||
is mostly the boot retry (1 vs 2 attempts costs ~1 min) — reinforcing that boot flake, not test time, drives
|
||||
the jitter.
|
||||
|
||||
## 2. Instrumented-test inventory
|
||||
|
||||
- **~263 instrumented `@Test` methods across 59 test classes** (`app/src/androidTest/…`; the runner
|
||||
reports "Starting 263 tests"). Confirmed by static count (`@Test` occurrences) and the CI log.
|
||||
- Distribution is **class-skewed**: a few heavy classes dominate — `MessageDaoTest` (17),
|
||||
`MigrationTest` (15), `MailboxScreenTest` (13), `AccountDataMigratorTest` (8), several DAO/`*Database`
|
||||
classes (7 each) — while most classes have 1–6.
|
||||
- The suite is a **mix** of Room/DAO/migration DB tests (CPU + disk on `google_apis_ps16k`) and Compose UI
|
||||
tests (Espresso/`createComposeRule`). No single test is a multi-minute outlier; 263 tests / ~8.8 min ≈
|
||||
**~2 s/test average**, so runtime is spread reasonably evenly and **count-based sharding will be
|
||||
approximately runtime-balanced** at N = 2–3.
|
||||
|
||||
At ~263 tests, **N = 2 (~131/shard) or N = 3 (~88/shard)** are the sensible shard counts. Beyond that the
|
||||
per-shard test time shrinks below the fixed boot/build cost and the split stops paying off (see §4).
|
||||
|
||||
## 3. Sharding approaches
|
||||
|
||||
### 3a. AndroidJUnitRunner built-in sharding across a GHA matrix — RECOMMENDED
|
||||
|
||||
`AndroidJUnitRunner` has first-class sharding: it hashes each test name into one of `numShards` buckets and
|
||||
runs only `shardIndex`'s bucket. AGP surfaces runner args through Gradle properties, so on the **existing
|
||||
hand-provisioned `connectedDebugAndroidTest`** (no GMD required) each shard runs:
|
||||
|
||||
```bash
|
||||
./gradlew connectedDebugAndroidTest \
|
||||
-Pandroid.testInstrumentationRunnerArguments.numShards=2 \
|
||||
-Pandroid.testInstrumentationRunnerArguments.shardIndex=${{ matrix.shard }}
|
||||
```
|
||||
|
||||
`shardIndex` is **0-based** (a bucket in `0..numShards-1`), so the matrix values are `[0, 1]`, **not**
|
||||
`[1, 2]` — `shardIndex=numShards` would run an empty bucket and silently drop half the suite.
|
||||
Wrapped in a `strategy.matrix.shard: [0, 1]` (or `[0, 1, 2]`) fan-out where each matrix leg provisions its
|
||||
**own** API 37 emulator and runs one shard. This is the same fan-in pattern the repo **already uses** for
|
||||
the `e2e` (API 29–36) matrix, and the same runner-arg channel `local_instrumented.py` already uses for
|
||||
`…arguments.class=` — so it is a known-good mechanism here, needs **no orchestrator, no Gradle-side change,
|
||||
and no branch-protection change** (see §5).
|
||||
|
||||
**Confirmed compatible with the hand-provisioned 16 KB job:** runner-arg sharding is a property of
|
||||
`AndroidJUnitRunner` + the AGP `connected*AndroidTest` task, entirely independent of *how* the AVD was
|
||||
created. GMD is irrelevant. Count-based, deterministic, and stable across runs.
|
||||
|
||||
### 3b. Alternatives (rejected)
|
||||
|
||||
- **Manual test-class partitioning** (`-Pandroid.testInstrumentationRunnerArguments.class=A,B,C` per shard,
|
||||
or `package`/annotation buckets): lets you hand-balance by runtime, but is **brittle** — every new test
|
||||
class must be manually assigned or it silently runs in no shard (coverage gap) or a wrong one. Not worth
|
||||
it for a ~0.5 min balance gain over hashing.
|
||||
- **Android Test Orchestrator** (`clearPackageData`): solves per-test process isolation, **not** wall-clock;
|
||||
it actually *slows* a run (fresh process per test). Orthogonal to sharding — skip.
|
||||
- **`maxParallelForks` (in-JVM):** N/A — that is a *JVM unit-test* knob (and the very thing #258 rejected
|
||||
because GreenMail binds fixed ports). Instrumented tests run on the device, not forked JVMs.
|
||||
|
||||
## 4. Expected wall-clock gain vs. CI cost
|
||||
|
||||
Model: an N-shard leg ≈ `B + T/N` (parallel), costing ≈ `N × (B + T/N)` emulator-minutes. Using the measured
|
||||
**B ≈ 8.3 min, T ≈ 8.8 min**:
|
||||
|
||||
| N | Leg time `B + T/N` | Δ vs today | Emulator-minutes `N × leg` | Cost multiple |
|
||||
|:-:|-------------------:|-----------:|---------------------------:|:-------------:|
|
||||
| 1 (today) | **17.1 min** | — | 17.1 | 1.0× |
|
||||
| **2** | **12.7 min** | **−4.4 min** | 25.4 | 1.5× |
|
||||
| 3 | 11.2 min | −5.9 min | 33.7 | 2.0× |
|
||||
| 4 | 10.5 min | −6.6 min | 42.0 | 2.5× |
|
||||
| ∞ | 8.3 min (floor = B) | −8.8 min | — | — |
|
||||
|
||||
But the **total-CI critical path** is `max(all jobs)`, and the API 29–36 E2E matrix already runs **~8.3–12.0
|
||||
min (API 30 ≈ 12.0 is its ceiling)**. So the API 37 leg only helps the pipeline until it drops to that wall:
|
||||
|
||||
| N | API 37 leg | **Total-CI critical path** = max(API 37, API 30≈12.0) | Total CI saved |
|
||||
|:-:|-----------:|:------------------------------------------------------:|---------------:|
|
||||
| 1 | 17.1 | **17.6** (API 37) | — |
|
||||
| **2** | 12.7 | **12.7** (API 37, just above the matrix wall) | **~4.9 min (~28%)** |
|
||||
| 3 | 11.2 | **12.0** (now **API 30** caps it) | ~5.6 min (~32%) |
|
||||
| 4 | 10.5 | 12.0 (API 30) — **no gain over N=3** | ~5.6 min |
|
||||
|
||||
**Point of diminishing returns.** Two effects compound:
|
||||
|
||||
1. **B ≈ T** gives a hard ~8.3 min floor for the leg itself (N = ∞).
|
||||
2. Long before that, the **~12.0 min API 30 matrix wall** caps *total* CI. N = 2 lands the leg at 12.7
|
||||
(~0.7 above the wall); N = 3 tucks it under the wall (API 30 takes over). **N = 3 is the last count that
|
||||
changes anything**; N ≥ 4 is pure waste unless the API 29–36 matrix is *also* sharded (a separate,
|
||||
larger effort).
|
||||
|
||||
**Verdict:** **N = 2 captures ~4.9 of the ~5.6 min theoretically achievable** — the overwhelming majority
|
||||
— for the least cost and flake. N = 3 collects the last ~0.7 min at +1 more preview emulator.
|
||||
|
||||
## 5. Risks / gotchas
|
||||
|
||||
1. **Flake multiplication (top code-risk).** `e2e-preview` is already the flakiest leg (16 KB preview image;
|
||||
boot/snapshot races; the `input keyevent 82` timing hazard; infra-vs-code ambiguity). N shards = N
|
||||
independent cold boots per pipeline, so `P(all shards boot)` = `p^N`. Mitigation is **built in**: each
|
||||
shard inherits the job's existing **two-attempt boot loop** (the memory note pegs a single un-retried
|
||||
boot race at ~2% → ~0.04% after two attempts), keeping aggregate boot success ~99.9% even at N = 3. Keep
|
||||
the retry loop per shard; do **not** collapse it to save time.
|
||||
2. **Runner concurrency (top practical-risk).** The pipeline already fans out 8 E2E matrix jobs +
|
||||
`e2e-preview` + 3 lighter jobs (~12 concurrent). N = 2/3 pushes peak to ~13/14 concurrent runners. **If
|
||||
the account's concurrent-job limit is hit, shards queue serially and the entire wall-clock gain
|
||||
evaporates** (or inverts). The project already actively manages runner allocation/priority (P0–P9), so
|
||||
this is a real, tracked constraint — confirm headroom before enabling, and give the preview shards the
|
||||
same priority as the rest of the E2E matrix.
|
||||
3. **`ci-passed` gate must require ALL shards — but needs no branch-protection edit.** Converting
|
||||
`e2e-preview` to a matrix makes GHA roll all shard legs under the one `e2e-preview` entry already in
|
||||
`ci-passed.needs`; the gate's `contains(needs.*.result, 'failure' | 'cancelled' | 'skipped')` check
|
||||
fails if **any** shard fails (a matrix job's `result` is `failure` when any leg fails). Branch protection
|
||||
only requires the single `CI passed` context, so **no protected-check list change** — same as the
|
||||
existing `e2e` matrix. Verified against the current gate wiring.
|
||||
4. **Artifact-name collision.** Each shard uploads its own `app/build/reports/androidTests/connected/` HTML
|
||||
report; `actions/upload-artifact@v7` **errors on duplicate names**. The report name must gain the shard
|
||||
index (e.g. `e2e-test-report-api37-preview-shard${{ matrix.shard }}`), mirroring the API-level suffix the
|
||||
`e2e` matrix already uses. Same for the boot-diagnostics artifact.
|
||||
5. **No cross-shard coverage merge needed (a simplifier vs #258).** #258's blocker was JaCoCo aggregation
|
||||
across shards. Here, **instrumented/E2E coverage is explicitly out of scope** (`app/build.gradle.kts`
|
||||
JaCoCo scoping + issue #192), so there is nothing to merge — shard results only need to fan into the pass/
|
||||
fail gate.
|
||||
6. **Cold-cache thundering herd.** The ~1 GB preview image is cached (`actions/cache`, keyed identically for
|
||||
all shards). On a **warm** cache all shards get a fast hit (steady state). On a **cold** cache (first run
|
||||
after a key change), all N shards download ~1 GB concurrently — a rare N× bandwidth spike, self-healing
|
||||
on the next run. Acceptable; no change needed.
|
||||
7. **Shard balance.** Count-based hashing is only *approximately* runtime-balanced; a shard that draws
|
||||
`MigrationTest` + the DAO-heavy classes may run marginally longer. Tolerable at N = 2–3 (§2); revisit only
|
||||
if a shard consistently lags.
|
||||
8. **`concurrency: cancel-in-progress` churn.** Unchanged semantics (all shards share the PR concurrency
|
||||
group, cancelled together on a new push), but there are now more in-flight jobs to cancel and re-trigger
|
||||
on each push — a small addition to the known CI merge-cascade thrash. No new failure mode.
|
||||
9. **Retry-parity gap — a *pre-existing* reliability asymmetry sharding must preserve (surfaced by #370).**
|
||||
The stable `e2e` matrix retries its test run **once** on failure (`ci.yml`, the two paired
|
||||
`reactivecircus/android-emulator-runner` "Run E2E tests" + "…(retry…)" steps), so a genuinely flaky test
|
||||
self-heals on API 29–36. **`e2e-preview` runs `connectedDebugAndroidTest` exactly once — no retry**, so
|
||||
the *same* flaky test **wedges the required gate on API 37**. This is exactly what flaked #370 (a real
|
||||
`SignaturesScreenTest` Room/`viewModelScope` teardown race, being fixed at the test level separately) —
|
||||
not a boot/timing issue. **Interaction with sharding (why it belongs here):** unlike **boot** flake,
|
||||
which sharding *multiplies* by N (risk #1), per-**test** flake is **not** amplified — every test still
|
||||
runs exactly once across the whole matrix, so a single flaky test lives in exactly one shard. But it
|
||||
still fails a *required* leg, so the gate needs a retry regardless of shard count. The right design is a
|
||||
**per-shard** retry: each shard retries only its own bucket, costing **`B + T/N`** (one shard's leg),
|
||||
strictly cheaper than the unsharded whole-suite retry (`B + T`). So sharding makes flake-recovery both
|
||||
still-necessary and *cheaper*. **Framing: mitigation, not a fix** — a blanket retry also masks genuine
|
||||
regressions, so surface the retried-but-passed case as a `::warning::` and keep the real fix test-level
|
||||
(as #370 does). See §6 for the recommendation and the implementation.
|
||||
|
||||
## 6. Recommendation (adopted)
|
||||
|
||||
**Worth doing: yes — done.** `e2e-preview` is the pipeline's critical path, so unlike #258 (unit tests, which
|
||||
finish ~8.5 min *inside* the E2E-bounded gate and were correctly closed as not-worthwhile) sharding this leg
|
||||
**directly** shortens total CI.
|
||||
|
||||
- **Adopted `N = 2`** via a `strategy.matrix.shard: [0, 1]` fan-out using AndroidJUnitRunner
|
||||
`numShards`/`shardIndex` (§3a). Expected total-CI critical path **~17.6 → ~12.7 min (~28% off)** for **+1
|
||||
emulator job**. Each shard keeps the two-attempt boot loop; the report/diagnostics artifact names carry the
|
||||
shard index; `e2e-preview` stays a single entry in `ci-passed.needs` (matrix fan-in keeps the single gate —
|
||||
both shards must pass; §5.3). `fail-fast: false` so a failing shard doesn't cancel its sibling.
|
||||
- **`N = 3` not adopted** — reserved for if the last ~0.7 min ever matters and runner headroom is comfortable;
|
||||
it moves the critical path onto the API 30 matrix leg (~12.0 min). **Never `N ≥ 4`** without also sharding
|
||||
the API 29–36 matrix.
|
||||
- **Local preflight stays single-emulator** — `api37_e2e.py` and `local_instrumented.py` keep their single
|
||||
hand-provisioned boot (not sharded). One free hypervisor per dev box; parallel local emulators risk freezing
|
||||
the machine (project memory). The sharding divergence is intentional and is documented in the job comment.
|
||||
|
||||
Two **reliability** fixes ship with sharding (from the #370 root-cause; §5 item 9) — together they make the
|
||||
API 37 leg *faster **and** more reliable*:
|
||||
|
||||
- **Retry parity — shipped (CI).** `e2e-preview` now gives each shard the **same single test-run retry** the
|
||||
`e2e` matrix has, as a **per-shard** retry (re-runs only that shard's tests, not the whole suite). **This is
|
||||
a mitigation, not a fix:** a blanket retry masks genuine regressions, so the retried-but-passed case is
|
||||
flagged as a `::warning::` and real flakes stay fixed at the test level (as #370 did). The retry count is
|
||||
**one**, not more. *Sharding interaction:* a per-shard retry is the natural fit and is cheaper than an
|
||||
unsharded retry — see §5 item 9. **Local mirror deferred:** mirroring the same single test-retry into
|
||||
`api37_e2e.py`'s `connectedDebugAndroidTest` step (for CI/local lockstep) is a small follow-up, kept out of
|
||||
this change because it can't be validated without booting a local emulator (which this change deliberately
|
||||
does not do). `api37_e2e.py` already matches CI on the boot-retry loop and `adb start-server`.
|
||||
- **`adb start-server` before the boot loop — shipped (CI).** Mirrors `api37_e2e.py`'s `wait_for_boot` (which
|
||||
already does this), avoiding the attempt-1 adb-daemon "Address already in use" bind race seen in #370
|
||||
(self-recovered there; free hardening).
|
||||
|
||||
### Relationship to #258 (unit-test sharding)
|
||||
|
||||
#258 was closed **not-worthwhile** because the unit-test job (~6.5 min) isn't on the critical path (E2E
|
||||
dominates), so sharding it saved ~0 wall-clock, and `maxParallelForks` collided on GreenMail's fixed ports.
|
||||
**Reused pattern:** *measure the critical path first, only shard what's on it.* API 37 preview **is** on it,
|
||||
so the conclusion flips to GO. **Distinct from #258:** different layer (on-device instrumented vs JVM),
|
||||
different mechanism (`numShards`/`shardIndex` matrix vs `maxParallelForks`), and **no coverage-merge
|
||||
constraint** (instrumented coverage is out of scope), which makes this strictly simpler to land.
|
||||
|
||||
## Implementation
|
||||
|
||||
This change converts `e2e-preview` to an `N = 2` shard matrix (`strategy.matrix.shard: [0, 1]`,
|
||||
`fail-fast: false`), each leg hand-provisioning its own API 37 emulator and running one shard via
|
||||
`-Pandroid.testInstrumentationRunnerArguments.numShards=2 -Pandroid.testInstrumentationRunnerArguments.shardIndex=<0|1>`.
|
||||
Each uploaded artifact name carries the shard index (`…-shard${{ matrix.shard }}`) — `upload-artifact@v7`
|
||||
errors on duplicate names. It also folds in the two §6 reliability fixes on the CI side: a **per-shard single
|
||||
test retry** (retry parity with the `e2e` matrix, flagged `::warning::` on the retried-but-passed case) and
|
||||
an **`adb start-server` before the boot loop**. The matching `api37_e2e.py` local retry mirror is a
|
||||
documented follow-up (§6) — not bundled here because it can't be validated without booting a local emulator.
|
||||
|
||||
**Validation.** Because a PR runs the workflow *from its own branch*, **this PR's own CI run is the
|
||||
validation** — both shards must go green and the real per-shard wall-clock is readable straight off that run
|
||||
(this is a CI-infra change, so a green pipeline is the "test", per #258's DoD note). Both shards fan into the
|
||||
single `e2e-preview` entry in `ci-passed.needs`; GHA's matrix aggregation makes `e2e-preview`'s result
|
||||
`failure` if either shard fails, so `ci-passed` (the branch-protection-required "CI passed" context) stays
|
||||
red unless **both** shards pass — no branch-protection change needed (§5.3).
|
||||
Reference in New Issue
Block a user