Convert minibench Java files to Kotlin by kirklandsign · Pull Request #19760 · pytorch/executorch

kirklandsign · 2026-05-26T04:54:58Z

Summary:
Convert BenchmarkActivity, BenchmarkMetric, LlmBenchmark, LlmModelRunner,
and ModelRunner from Java to Kotlin. LlmModelRunnerCallback.kt was already
Kotlin.

Key changes:

Use Kotlin idioms: when expressions, data classes, string templates,
scope functions, extension methods
Use lateinit/val where appropriate instead of mutable nullable fields
Replace anonymous Handler subclasses with private classes
Keep all public API signatures compatible
No BUCK changes needed (OSS-only gradle build)

Differential Revision: D106195816

Summary: Convert BenchmarkActivity, BenchmarkMetric, LlmBenchmark, LlmModelRunner, and ModelRunner from Java to Kotlin. LlmModelRunnerCallback.kt was already Kotlin. Key changes: - Use Kotlin idioms: when expressions, data classes, string templates, scope functions, extension methods - Use lateinit/val where appropriate instead of mutable nullable fields - Replace anonymous Handler subclasses with private classes - Keep all public API signatures compatible - No BUCK changes needed (OSS-only gradle build) Differential Revision: D106195816

pytorch-bot · 2026-05-26T04:55:02Z

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/19760

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❌ 1 New Failure, 2 Unrelated Failures, 1 Unclassified Failure

As of commit c035397 with merge base 03e14ef ():

NEW FAILURE - The following job has failed:

pull / android / run-emulator (gh)
The process '/usr/local/lib/android/sdk/platform-tools/adb' failed with exit code 224

UNCLASSIFIED FAILURE - DrCI could not classify the following job because the workflow did not run on the merge base. The failure may be pre-existing on trunk or introduced by this PR:

Check Labels (gh) (this job did not run on the merge base, so DrCI cannot tell whether the failure is pre-existing)

BROKEN TRUNK - The following jobs failed but were present on the merge base:

👉 Rebase onto the `viable/strict` branch to avoid these failures

pull / unittest / macos / macos-job (gh) (trunk failure)
##[error]The operation was canceled.
pull / unittest-editable / macos / macos-job (gh) (trunk failure)
##[error]The operation was canceled.

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meta-codesync · 2026-05-26T04:55:23Z

@kirklandsign has exported this pull request. If you are a Meta employee, you can view the originating Diff in D106195816.

kirklandsign · 2026-05-26T04:56:03Z

@claude review

github-actions · 2026-05-26T04:56:05Z

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claude · 2026-05-26T04:56:48Z

Claude finished @kirklandsign's task in 1m 33s —— View job

Review: Convert minibench Java files to Kotlin

Read new Kotlin files and compare with deleted Java files
Check Kotlin idioms and best practices
Verify API compatibility
Post review feedback

Overall this is a clean, well-done Java-to-Kotlin conversion. The Kotlin idioms are used appropriately and the code is more concise and readable. A few observations:

Bug fix (good catch)

LlmModelRunner.kt:28 — The original Java code at LlmModelRunner.java:56 hardcoded 0.8f for temperature:

mModule = new LlmModule(mModelFilePath, mTokenizerFilePath, 0.8f);

The Kotlin version correctly passes through the temperature parameter:

val module: LlmModule = LlmModule(modelFilePath, tokenizerFilePath, temperature)

Nice fix.

Minor observations

Visibility increase — LlmModelRunner.kt:26-28: module and callback are now public val (Kotlin default), whereas the Java equivalents were package-private. This is necessary for the private LlmModelRunnerHandler class to access them, but it does expose these fields to external callers. Consider using internal if you want to restrict to the module level, though for an app (not a library) this is fine as-is.
BenchmarkActivity.kt:44 — The added return after finish() in the catch block is a behavior improvement over the Java code (which fell through and continued setting up the handler thread pointlessly after calling finish()). Good change.
BenchmarkActivity.kt:49 — modelDir.listFiles()!! will NPE if the directory doesn't exist. The Java had the same potential issue, so this isn't a regression, but worth noting if you want to add error handling in a follow-up.
BenchmarkMetric.kt:20-24 — BenchmarkModel is now a data class, which adds equals/hashCode/toString/copy/componentN. Since this is serialized with Gson (field reflection), serialization behavior is unchanged. The extra methods are a net positive.
LlmBenchmark.kt — The StatsInfo.toString() debug method from Java is dropped. Acceptable since it wasn't used in production code paths.

Verdict

Looks good — clean idiomatic conversion with proper use of lateinit, when expressions, const val, data class, private file-level classes, and string templates. The temperature bug fix is a bonus. No functional regressions spotted.

Copilot

Pull request overview

This PR migrates the Android minibench benchmark app’s core runner/metric/activity logic from Java to Kotlin, aiming to preserve behavior and public surfaces while adopting Kotlin idioms.

Changes:

Replaced Java implementations of BenchmarkActivity, BenchmarkMetric, ModelRunner, LlmBenchmark, and LlmModelRunner with Kotlin equivalents.
Refactored background-thread message handling to dedicated Handler classes and updated call sites accordingly.
Updated the sample unit test to idiomatic Kotlin imports/syntax.

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
extension/benchmark/android/benchmark/app/src/test/java/org/pytorch/minibench/ExampleUnitTest.kt	Kotlin syntax/import cleanup for the example unit test.
extension/benchmark/android/benchmark/app/src/main/java/org/pytorch/minibench/ModelRunner.kt	Kotlin port of model load/forward benchmarking and metric emission.
extension/benchmark/android/benchmark/app/src/main/java/org/pytorch/minibench/ModelRunner.java	Removed Java implementation after Kotlin migration.
extension/benchmark/android/benchmark/app/src/main/java/org/pytorch/minibench/LlmModelRunner.kt	Kotlin port of LLM module worker-thread runner and callbacks.
extension/benchmark/android/benchmark/app/src/main/java/org/pytorch/minibench/LlmModelRunner.java	Removed Java implementation after Kotlin migration.
extension/benchmark/android/benchmark/app/src/main/java/org/pytorch/minibench/LlmBenchmark.kt	Kotlin port of LLM benchmark orchestration and metrics.
extension/benchmark/android/benchmark/app/src/main/java/org/pytorch/minibench/LlmBenchmark.java	Removed Java implementation after Kotlin migration.
extension/benchmark/android/benchmark/app/src/main/java/org/pytorch/minibench/BenchmarkMetric.kt	Kotlin port of metric/model parsing + device info container.
extension/benchmark/android/benchmark/app/src/main/java/org/pytorch/minibench/BenchmarkMetric.java	Removed Java implementation after Kotlin migration.
extension/benchmark/android/benchmark/app/src/main/java/org/pytorch/minibench/BenchmarkActivity.kt	Kotlin port of benchmark Activity startup, worker thread, and result writing.
extension/benchmark/android/benchmark/app/src/main/java/org/pytorch/minibench/BenchmarkActivity.java	Removed Java implementation after Kotlin migration.

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+
+      results.add(
+          BenchmarkMetric(
+              benchmarkModel,
+              "avg_inference_latency(ms)",
+              latency.average(),
+              0.0,
+          ))
+      results.add(
+          BenchmarkMetric(
+              benchmarkModel,
+              "trimmean_inference_latency(ms)",
+              trimmed.average(),


+
+      results.add(
+          BenchmarkMetric(
+              benchmarkModel,
+              "avg_inference_latency(ms)",
+              latency.average(),
+              0.0,
+          ))
+      results.add(
+          BenchmarkMetric(
+              benchmarkModel,
+              "trimmean_inference_latency(ms)",
+              trimmed.average(),


+    runner = LlmModelRunner(modelFile, tokenizerPath, temperature, this)
+    statsInfo.loadStart = System.nanoTime()


+
+    handler.sendEmptyMessage(BenchmarkHandler.MESSAGE_RUN_BENCHMARK)
+  }
+


+  val module: LlmModule = LlmModule(modelFilePath, tokenizerFilePath, temperature)
+  private val handlerThread: HandlerThread = HandlerThread("LlmModelRunner")
+  private val handler: Handler
+
+  init {
+    handlerThread.start()
+    handler = LlmModelRunnerHandler(handlerThread.looper, this)
+    handler.sendEmptyMessage(LlmModelRunnerHandler.MESSAGE_LOAD_MODEL)
+  }


+  class DeviceInfo {
+    val device: String = Build.BRAND
+    val arch: String = Build.MODEL
+    val os: String = "Android ${Build.VERSION.RELEASE}"
+    val totalMem: Long = ActivityManager.MemoryInfo().totalMem
+    val availMem: Long = ActivityManager.MemoryInfo().availMem
+  }


kirklandsign requested a review from Gasoonjia as a code owner May 26, 2026 04:54

Copilot AI review requested due to automatic review settings May 26, 2026 04:54

meta-cla Bot added the CLA Signed This label is managed by the Facebook bot. Authors need to sign the CLA before a PR can be reviewed. label May 26, 2026

Copilot started reviewing on behalf of kirklandsign May 26, 2026 04:55 View session

meta-codesync Bot added fb-exported meta-exported labels May 26, 2026

Copilot AI reviewed May 26, 2026

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shoumikhin approved these changes May 26, 2026

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kirklandsign merged commit 6128a45 into main May 26, 2026
181 of 193 checks passed

kirklandsign deleted the export-D106195816 branch May 26, 2026 16:29

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Convert minibench Java files to Kotlin#19760

Convert minibench Java files to Kotlin#19760
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kirklandsign commented May 26, 2026

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		runner = LlmModelRunner(modelFile, tokenizerPath, temperature, this)
		statsInfo.loadStart = System.nanoTime()


		handler.sendEmptyMessage(BenchmarkHandler.MESSAGE_RUN_BENCHMARK)
		}

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🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/19760

❌ 1 New Failure, 2 Unrelated Failures, 1 Unclassified Failure

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Review: Convert minibench Java files to Kotlin

Bug fix (good catch)

Minor observations

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