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Fix race condition when interrupting applications #9827

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Merged
merged 2 commits into from
Apr 29, 2025
Merged

Fix race condition when interrupting applications #9827

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f17c861
Fix error reporting when interrupting applications
kyri-petrou Apr 27, 2025
2ef6734
PR comments
kyri-petrou Apr 28, 2025
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32 changes: 13 additions & 19 deletions core/jvm-native/src/main/scala/zio/ZIOAppPlatformSpecific.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -24,20 +24,16 @@ private[zio] trait ZIOAppPlatformSpecific { self: ZIOApp =>
} yield result).provideLayer(newLayer.tapErrorCause(ZIO.logErrorCause(_)))

runtime.unsafe.run {
ZIO.uninterruptibleMask { restore =>
ZIO.uninterruptible {
for {
fiberId <- ZIO.fiberId
p <- Promise.make[Nothing, Set[FiberId.Runtime]]
fiber <- restore(workflow).onExit { exit0 =>
val exitCode = if (exit0.isSuccess) ExitCode.success else ExitCode.failure
val interrupt = interruptRootFibers(p)
// If we're shutting down due to an external signal, the shutdown hook will fulfill the promise
// Otherwise it means we're shutting down due to normal completion and we need to fulfill the promise
ZIO.unless(shuttingDown.get())(p.succeed(Set(fiberId))) *> interrupt *> exit(exitCode)
fiber <- workflow.interruptible.exitWith { exit0 =>
val exitCode = if (exit0.isSuccess) ExitCode.success else ExitCode.failure
interruptRootFibers(fiberId).as(exitCode)
}.fork
_ <-
ZIO.succeed(Platform.addShutdownHook { () =>
if (!shuttingDown.getAndSet(true)) {
if (shuttingDown.compareAndSet(false, true)) {

if (FiberRuntime.catastrophicFailure.get) {
println(
Expand All @@ -48,28 +44,26 @@ private[zio] trait ZIOAppPlatformSpecific { self: ZIOApp =>
"Check the logs for more details and consider overriding `Runtime.reportFatal` to capture context."
)
} else {
// NOTE: try-catch likely not needed,
// but guarding against cases where the submission of the task fails spuriously
try {
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Does this still need to be in a try?

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There is an extremely low chance (I can't reproduce, but theoretically it might be possible), that the submission of the task to the executor is rejected (due to shutdown) and throws a RejectedExecutionException.

As I said, I'm not even sure if that's possible but just wanted to be extra safe just in case

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I added a comment to clarify

val completePromise = ZIO.fiberIdWith(fid2 => p.succeed(Set(fiberId, fid2)))
runtime.unsafe.run(completePromise *> fiber.interrupt)
fiber.tellInterrupt(Cause.interrupt(fiberId))
} catch {
case _: Throwable =>
}
}

()
}
})
result <- fiber.join
} yield result
_ <- exit(result)
} yield ()
}
}.getOrThrowFiberFailure()
}

private def interruptRootFibers(p: Promise[Nothing, Set[FiberId.Runtime]])(implicit trace: Trace): UIO[Unit] =
private def interruptRootFibers(mainFiberId: FiberId)(implicit trace: Trace): UIO[Unit] =
for {
ignoredIds <- p.await
roots <- Fiber.roots
_ <- Fiber.interruptAll(roots.view.filter(fiber => fiber.isAlive() && !ignoredIds(fiber.id)))
roots <- Fiber.roots
_ <- Fiber.interruptAll(roots.view.filter(fiber => fiber.isAlive() && (fiber.id != mainFiberId)))
} yield ()

}
8 changes: 4 additions & 4 deletions core/shared/src/main/scala/zio/ZIOApp.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -72,7 +72,7 @@ trait ZIOApp extends ZIOAppPlatformSpecific with ZIOAppVersionSpecific {
*/
final def exit(code: ExitCode)(implicit trace: Trace): UIO[Unit] =
ZIO.succeed {
if (!shuttingDown.getAndSet(true)) {
if (shuttingDown.compareAndSet(false, true)) {
try Platform.exit(code.code)(Unsafe.unsafe)
catch {
case _: SecurityException =>
Expand All @@ -99,8 +99,8 @@ trait ZIOApp extends ZIOAppPlatformSpecific with ZIOAppVersionSpecific {
def runtime: Runtime[Any] = Runtime.default

protected def installSignalHandlers(runtime: Runtime[Any])(implicit trace: Trace): UIO[Any] =
ZIO.attempt {
if (!ZIOApp.installedSignals.getAndSet(true)) {
ZIO.ignore {
if (ZIOApp.installedSignals.compareAndSet(false, true)) {
val dumpFibers =
() => runtime.unsafe.run(Fiber.dumpAll)(trace, Unsafe.unsafe).getOrThrowFiberFailure()(Unsafe.unsafe)

Expand All @@ -109,7 +109,7 @@ trait ZIOApp extends ZIOAppPlatformSpecific with ZIOAppVersionSpecific {
Platform.addSignalHandler("USR1", dumpFibers)(Unsafe.unsafe)
}
}
}.ignore
}
}

object ZIOApp {
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