hello I encountered something weird in Production....

# k2-adopters

[mitch]

hello I encountered something weird in Production... we had a suspend function all of a sudden started exploding with

java.lang.NullPointerException: Cannot invoke "kotlin.coroutines.Continuation.getContext()" because "$completion" is null

with the offending stack trace (which unfortunately I can't share) pointed to a simple currentCoroutineContext() , to a generic code that have been running in production for quite some time without issues:

suspend fun <A> withObservability(fx: suspend ReactiveLogger.() -> A): A {
  currentCoroutineContext() // blew up here
  ...
}

Also it's not deterministic: it doesn't happen to anywhere else in the codebase but one very specific endpoint. We've been using this function literally everywhere in the code and has been running rock solid for at least the last ~4 years. This is a bit over my head and I'm trying to understand how can I debug this.. why would the completion be null?
also maybe a red herring but we started seeing this after we upgraded Kotlin from 1.9.21 to 1.9.22

kotlinx.coroutines version 1.7.3
kotlin version 1.9.22
java 17.0.9

CI compilation passes, but potentially have generated a bad code.

After some investigation, with latest intellij somehow compilation failed with this error:
https://kotlinlang.slack.com/archives/C1CFAFJSK/p1704872052059009?thread_ts=1704719278.461759&cid=C1CFAFJSK

org.jetbrains.kotlin.backend.common.BackendException: Backend Internal error: Exception during IR lowering
File being compiled: /Users/myuwono/Development/path/to/File.kt
The root cause java.lang.AssertionError was thrown at: org.jetbrains.kotlin.backend.jvm.lower.AddContinuationLoweringKt.retargetToSuspendView(AddContinuationLowering.kt:500)
	at org.jetbrains.kotlin.backend.common.CodegenUtil.reportBackendException(CodegenUtil.kt:253)
	at org.jetbrains.kotlin.backend.common.CodegenUtil.reportBackendException$default(CodegenUtil.kt:237)
	at org.jetbrains.kotlin.backend.common.phaser.PerformByIrFilePhase.invokeSequential(performByIrFile.kt:65)
	at org.jetbrains.kotlin.backend.common.phaser.PerformByIrFilePhase.invoke(performByIrFile.kt:52)
	at org.jetbrains.kotlin.backend.common.phaser.PerformByIrFilePhase.invoke(performByIrFile.kt:38)
	at org.jetbrains.kotlin.backend.common.phaser.NamedCompilerPhase.phaseBody(CompilerPhase.kt:147)
	at org.jetbrains.kotlin.backend.common.phaser.AbstractNamedCompilerPhase.invoke(CompilerPhase.kt:94)
	at org.jetbrains.kotlin.backend.common.phaser.CompositePhase.invoke(PhaseBuilders.kt:29)
	at org.jetbrains.kotlin.backend.common.phaser.CompositePhase.invoke(PhaseBuilders.kt:16)
	at org.jetbrains.kotlin.backend.common.phaser.NamedCompilerPhase.phaseBody(CompilerPhase.kt:147)
	at org.jetbrains.kotlin.backend.common.phaser.AbstractNamedCompilerPhase.invoke(CompilerPhase.kt:94)
	at org.jetbrains.kotlin.backend.common.phaser.CompilerPhaseKt.invokeToplevel(CompilerPhase.kt:43)
	at org.jetbrains.kotlin.backend.jvm.JvmIrCodegenFactory.invokeLowerings(JvmIrCodegenFactory.kt:348)
	at org.jetbrains.kotlin.cli.jvm.compiler.KotlinToJVMBytecodeCompiler.runLowerings(KotlinToJVMBytecodeCompiler.kt:330)
	at org.jetbrains.kotlin.cli.jvm.compiler.KotlinToJVMBytecodeCompiler.compileModules$cli(KotlinToJVMBytecodeCompiler.kt:114)
	at org.jetbrains.kotlin.cli.jvm.compiler.KotlinToJVMBytecodeCompiler.compileModules$cli$default(KotlinToJVMBytecodeCompiler.kt:43)
	at org.jetbrains.kotlin.cli.jvm.K2JVMCompiler.doExecute(K2JVMCompiler.kt:165)
	at org.jetbrains.kotlin.cli.jvm.K2JVMCompiler.doExecute(K2JVMCompiler.kt:50)
	at org.jetbrains.kotlin.cli.common.CLICompiler.execImpl(CLICompiler.kt:104)
	at org.jetbrains.kotlin.cli.common.CLICompiler.execImpl(CLICompiler.kt:48)
	at org.jetbrains.kotlin.cli.common.CLITool.exec(CLITool.kt:101)
	at org.jetbrains.kotlin.incremental.IncrementalJvmCompilerRunner.runCompiler(IncrementalJvmCompilerRunner.kt:463)
	at org.jetbrains.kotlin.incremental.IncrementalJvmCompilerRunner.runCompiler(IncrementalJvmCompilerRunner.kt:62)
	at org.jetbrains.kotlin.incremental.IncrementalCompilerRunner.doCompile(IncrementalCompilerRunner.kt:477)
	at org.jetbrains.kotlin.incremental.IncrementalCompilerRunner.compileImpl(IncrementalCompilerRunner.kt:400)
	at org.jetbrains.kotlin.incremental.IncrementalCompilerRunner.tryCompileIncrementally$lambda$6$compile(IncrementalCompilerRunner.kt:231)
	at org.jetbrains.kotlin.incremental.IncrementalCompilerRunner.tryCompileIncrementally(IncrementalCompilerRunner.kt:247)
	at org.jetbrains.kotlin.incremental.IncrementalCompilerRunner.compile(IncrementalCompilerRunner.kt:116)
	at org.jetbrains.kotlin.daemon.CompileServiceImplBase.execIncrementalCompiler(CompileServiceImpl.kt:657)
	at org.jetbrains.kotlin.daemon.CompileServiceImplBase.access$execIncrementalCompiler(CompileServiceImpl.kt:105)
	at org.jetbrains.kotlin.daemon.CompileServiceImpl.compile(CompileServiceImpl.kt:1624)
	at jdk.internal.reflect.GeneratedMethodAccessor94.invoke(Unknown Source)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:568)
	at java.rmi/sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:360)
	at java.rmi/sun.rmi.transport.Transport$1.run(Transport.java:200)
	at java.rmi/sun.rmi.transport.Transport$1.run(Transport.java:197)
	at java.base/java.security.AccessController.doPrivileged(AccessController.java:712)
	at java.rmi/sun.rmi.transport.Transport.serviceCall(Transport.java:196)
	at java.rmi/sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:587)
	at java.rmi/sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:828)
	at java.rmi/sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.lambda$run$0(TCPTransport.java:705)
	at java.base/java.security.AccessController.doPrivileged(AccessController.java:399)
	at java.rmi/sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:704)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
	at java.base/java.lang.Thread.run(Thread.java:833)

and I didn't enable K2...

[semoro]

Hello! Please note that K2JVMCompiler has nothing to do with K2 itself 🤯 and it stands for Kotlin TO JVM compiler
In fact, it is different abbreviation that was introduced many years ago. (2012 🙂 )
https://github.com/JetBrains/kotlin/commit/9f92b0b5d7c0b034050464410868cd8705128704#diff-b0c9a3a54bc6f98310c511482[…]48fcba4ad2a9419e5bcfa6803114ce7

My apologies for the confusion

[semoro]

However, you are indeed facing a compiler bug. Please file a youtrack issue for it.