Production builds' stacktraces are terrible

[swankjesse]

Here’s a stacktrace from a debug build:

app.cash.zipline.ZiplineException: Exception: boom!
	at captureStack (js-ir/runtime/coreRuntime.kt:48)
	at Exception_init_$Create$_0 (kotlin-kotlin-stdlib.js)
	at <anonymous> (src/commonMain/kotlin/com/squareup/cash/treehouse/playground/samples/ErrorRecovery.kt:49)
	at <anonymous> (js-ir/src/kotlin/coroutines_13/CoroutineImpl.kt:55)
	at <anonymous> (kotlin-kotlin-stdlib.js)
	at resume (mnt/agent/work/44ec6e850d5c63f0/kotlinx-coroutines-core/common/src/internal/DispatchedTask.kt:62)
	at dispatch (mnt/agent/work/44ec6e850d5c63f0/kotlinx-coroutines-core/common/src/internal/DispatchedTask.kt:168)
	at dispatchResume (mnt/agent/work/44ec6e850d5c63f0/kotlinx-coroutines-core/common/src/CancellableContinuationImpl.kt:474)
	at resumeImpl (mnt/agent/work/88b0986a7186d029/atomicfu/src/commonMain/kotlin/kotlinx/atomicfu/AtomicFU.common.kt:508)
	at resumeImpl$default (mnt/agent/work/44ec6e850d5c63f0/kotlinx-coroutines-core/common/src/CancellableContinuationImpl.kt:1234)
	at <anonymous> (mnt/agent/work/44ec6e850d5c63f0/kotlinx-coroutines-core/common/src/CancellableContinuationImpl.kt:595)
	at <anonymous> (src/kotlin/util/Standard.kt:48)
	at apply (native)
	at <anonymous> (Users/runner/work/zipline/zipline/zipline/src/jsMain/kotlin/app/cash/zipline/GlobalBridge.kt:72)
	at <anonymous> (Users/runner/work/zipline/zipline/zipline/src/commonMain/kotlin/app/cash/zipline/internal/GuestService.kt)
	at <anonymous> (zipline-root-zipline.js)
	at <anonymous> (Users/runner/work/zipline/zipline/zipline/src/commonMain/kotlin/app/cash/zipline/internal/bridge/InboundService.kt:1390)
	at <anonymous> (Users/runner/work/zipline/zipline/zipline/src/commonMain/kotlin/app/cash/zipline/internal/bridge/Endpoint.kt:99)
	at <anonymous> (zipline-root-zipline.js)
	at <anonymous> (Users/runner/work/zipline/zipline/zipline/src/jsMain/kotlin/app/cash/zipline/GlobalBridge.kt)
	at <anonymous> (zipline-root-zipline.js)
	at app.cash.zipline.internal.GuestService$Companion$Adapter$GeneratedOutboundService.runJob(GuestService.kt:23)
	at app.cash.zipline.internal.CoroutineEventLoop$DelayedJob$run$1.invokeSuspend(CoroutineEventLoop.kt:61)
	at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
	at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:108)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1137)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:637)
	at java.lang.Thread.run(Thread.java:1012)

And the same from a production build:

app.cash.zipline.ZiplineException: $o: boom!
	at Eu (treehouse.js)
	at vo (treehouse.js)
	at <anonymous> (treehouse.js)
	at <anonymous> (treehouse.js)
	at <anonymous> (treehouse.js)
	at dl (treehouse.js)
	at <anonymous> (treehouse.js)
	at _r (treehouse.js)
	at vr (treehouse.js)
	at wr (treehouse.js)
	at <anonymous> (treehouse.js)
	at <anonymous> (treehouse.js)
	at apply (native)
	at <anonymous> (treehouse.js)
	at <anonymous> (treehouse.js)
	at <anonymous> (treehouse.js)
	at <anonymous> (treehouse.js)
	at <anonymous> (treehouse.js)
	at <anonymous> (treehouse.js)
	at <anonymous> (treehouse.js)
	at <anonymous> (treehouse.js)
	at app.cash.zipline.internal.GuestService$Companion$Adapter$GeneratedOutboundService.runJob(GuestService.kt:23)
	at app.cash.zipline.internal.CoroutineEventLoop$DelayedJob$run$1.invokeSuspend(CoroutineEventLoop.kt:61)
	at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
	at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:108)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1137)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:637)
	at java.lang.Thread.run(Thread.java:1012)

I really don’t like losing both function names and line numbers. When fixing we should confirm the resulting binary size isn’t adversely impacted.

[swankjesse]

The root problem is the JS file we’re generating our .zipline from is aggressively minified, and that deprives QuickJS of line number information.

I was able to fix by creating webpack.config.d/treehouseWebpackConfig.js in the module directory with these contents:

config.optimization = config.optimization || {};
const TerserPlugin = require("terser-webpack-plugin");
config.optimization.minimizer = [
  new TerserPlugin({
    terserOptions: {
      compress: {
        sequences: false,
      },
      mangle: false,
      format: {
        beautify: true,
        braces: true,
      }
    },
  }),
];

[swankjesse]

The costs of good debug data are too damn high!

                                    .zipline size        gzipped size
A NO DEBUG DATA                    2,856,719             941,474
B MANGLE CLASS + FUNCTION NAMES    3,400,044 (+19%)    1,193,241 (+27%)
C OMIT INSTRUCTION LINE NUMBERS    3,690,174 (+29%)    1,218,497 (+29%)
D TRUNCATE FILE PATH               3,642,791 (+28%)    1,338,461 (+42%)
E (B + C)                          3,218,986 (+13%)    1,064,318 (+13%)
F FULL DEBUG DATA                  3,871,128 (+35%)    1,346,230 (+42%)

Before closing this we should zipline { } Gradle plugin options for these:

• Stripping the pc2line table
• Mangling class + function names