zio · kyri-petrou · Jan 22, 2025 · Jan 20, 2025 · Jan 20, 2025 · Jan 21, 2025
diff --git a/core/shared/src/main/scala/zio/Fiber.scala b/core/shared/src/main/scala/zio/Fiber.scala
@@ -543,6 +543,13 @@ object Fiber extends FiberPlatformSpecific {
      */
     private[zio] def deleteFiberRef(ref: FiberRef[_]): Unit
 
+    /**
+     * Generates a full stack trace from the reified stack.
+     *
+     * '''NOTE''': This method must be invoked by the fiber itself.
+     */
+    private[zio] def generateStackTrace(): StackTrace
+
     /**
      * Retrieves the current executor that effects are executed on.
      *

diff --git a/core/shared/src/main/scala/zio/ZIO.scala b/core/shared/src/main/scala/zio/ZIO.scala
@@ -3240,12 +3240,12 @@ object ZIO extends ZIOCompanionPlatformSpecific with ZIOCompanionVersionSpecific
    * Returns an effect that models failure with the specified `Cause`.
    */
   def failCause[E](cause: => Cause[E])(implicit trace0: Trace): IO[E, Nothing] =
-    ZIO.stackTrace(trace0).flatMap { trace =>
-      FiberRef.currentLogSpan.getWith { spans =>
-        FiberRef.currentLogAnnotations.getWith { annotations =>
-          Exit.failCause(cause.applyAll(trace, spans, annotations))
-        }
-      }
+    ZIO.withFiberRuntime[Any, E, Nothing] { (state, _) =>
+      val trace = state.generateStackTrace()
+      val refs  = state.getFiberRefs(false)
+      val spans = refs.getOrDefault(FiberRef.currentLogSpan)
+      val anns  = refs.getOrDefault(FiberRef.currentLogAnnotations)
+      Exit.failCause(cause.applyAll(trace, spans, anns))
     }
 
   /**
@@ -4869,7 +4869,9 @@ object ZIO extends ZIOCompanionPlatformSpecific with ZIOCompanionVersionSpecific
    * Capture ZIO stack trace at the current point.
    */
   def stackTrace(implicit trace: Trace): UIO[StackTrace] =
-    GenerateStackTrace(trace)
+    ZIO.withFiberRuntime[Any, Nothing, StackTrace] { (state, _) =>
+      Exit.succeed(state.generateStackTrace())
+    }
 
   /**
    * Tags each metric in this effect with the specific tag.
@@ -6143,6 +6145,7 @@ object ZIO extends ZIOCompanionPlatformSpecific with ZIOCompanionVersionSpecific
       def scope(oldRuntimeFlags: RuntimeFlags): ZIO[R, E, A] = f(oldRuntimeFlags)
     }
   }
+  @deprecated("Kept for binary compatibility only", since = "2.1.15")
   private[zio] final case class GenerateStackTrace(trace: Trace) extends ZIO[Any, Nothing, StackTrace]
   private[zio] final case class Stateful[R, E, A](
     trace: Trace,

diff --git a/core/shared/src/main/scala/zio/internal/FiberRuntime.scala b/core/shared/src/main/scala/zio/internal/FiberRuntime.scala
@@ -510,12 +510,13 @@ final class FiberRuntime[E, A](fiberId: FiberId.Runtime, fiberRefs0: FiberRefs,
    *
    * '''NOTE''': This method must be invoked by the fiber itself.
    */
-  private def generateStackTrace(): StackTrace = {
+  private[zio] def generateStackTrace(): StackTrace = {
     val builder = stackTraceBuilderPool.get()
 
     val stack = _stack
     val size  = _stackSize // racy
 
+    builder += _lastTrace
     try {
       if (stack ne null) {
         var i = (if (stack.length < size) stack.length else size) - 1
@@ -1221,14 +1222,14 @@ final class FiberRuntime[E, A](fiberId: FiberId.Runtime, fiberRefs0: FiberRefs,
                 return failure
               }
 
-            case gen0: GenerateStackTrace =>
-              updateLastTrace(gen0.trace)
-              cur = Exit.succeed(generateStackTrace())
-
             case updateRuntimeFlags: UpdateRuntimeFlags =>
               updateLastTrace(updateRuntimeFlags.trace)
               cur = patchRuntimeFlags(updateRuntimeFlags.update, null, Exit.unit)
 
+            case gen0: GenerateStackTrace =>
+              updateLastTrace(gen0.trace)
+              cur = Exit.succeed(generateStackTrace())
+
             // Should be unreachable, but we keep it to be backwards compatible
             case update0: UpdateRuntimeFlagsWithin[Any, Any, Any] =>
               assert(DisableAssertions) // Will raise an error in tests but not in released artifact