JVM multithreaded scope pool now turned on by default

lynglib/src/androidMain/kotlin/net/sergeych/lyng/ScopePoolAndroid.kt

@@ -0,0 +1,38 @@
+package net.sergeych.lyng
+
+import net.sergeych.lyng.obj.Obj
+import net.sergeych.lyng.obj.ObjVoid
+
+/**
+ * Android actual: per-thread scope frame pool backed by ThreadLocal.
+ */
+actual object ScopePool {
+    private const val MAX_POOL_SIZE = 64
+    private val threadLocalPool: ThreadLocal<ArrayDeque<Scope>?> = ThreadLocal()
+
+    private fun pool(): ArrayDeque<Scope> {
+        var p = threadLocalPool.get()
+        if (p == null) {
+            p = ArrayDeque<Scope>(MAX_POOL_SIZE)
+            threadLocalPool.set(p)
+        }
+        return p
+    }
+
+    actual fun borrow(parent: Scope, args: Arguments, pos: Pos, thisObj: Obj): Scope {
+        val pool = pool()
+        val s = if (pool.isNotEmpty()) pool.removeLast() else Scope(parent, args, pos, thisObj)
+        if (s.parent !== parent || s.args !== args || s.pos !== pos || s.thisObj !== thisObj) {
+            s.resetForReuse(parent, args, pos, thisObj)
+        } else {
+            s.frameId = nextFrameId()
+        }
+        return s
+    }
+
+    actual fun release(scope: Scope) {
+        val pool = pool()
+        scope.resetForReuse(parent = null, args = Arguments.EMPTY, pos = Pos.builtIn, thisObj = ObjVoid)
+        if (pool.size < MAX_POOL_SIZE) pool.addLast(scope)
+    }
+}

lynglib/src/commonMain/kotlin/net/sergeych/lyng/Arguments.kt

@@ -31,7 +31,7 @@ import net.sergeych.lyng.obj.ObjList
          for (pa in this) {
              if (pa.isSplat) { hasSplat = true; break }
              count++
-             if (count > 3) break
+             if (count > 8) break
          }
          if (!hasSplat && count == this.size) {
              val quick = when (count) {
@@ -63,6 +63,36 @@ import net.sergeych.lyng.obj.ObjList
                      val a4 = this.elementAt(4).value.execute(scope)
                      Arguments(listOf(a0, a1, a2, a3, a4), tailBlockMode)
                  }
+                 6 -> {
+                     val a0 = this.elementAt(0).value.execute(scope)
+                     val a1 = this.elementAt(1).value.execute(scope)
+                     val a2 = this.elementAt(2).value.execute(scope)
+                     val a3 = this.elementAt(3).value.execute(scope)
+                     val a4 = this.elementAt(4).value.execute(scope)
+                     val a5 = this.elementAt(5).value.execute(scope)
+                     Arguments(listOf(a0, a1, a2, a3, a4, a5), tailBlockMode)
+                 }
+                 7 -> {
+                     val a0 = this.elementAt(0).value.execute(scope)
+                     val a1 = this.elementAt(1).value.execute(scope)
+                     val a2 = this.elementAt(2).value.execute(scope)
+                     val a3 = this.elementAt(3).value.execute(scope)
+                     val a4 = this.elementAt(4).value.execute(scope)
+                     val a5 = this.elementAt(5).value.execute(scope)
+                     val a6 = this.elementAt(6).value.execute(scope)
+                     Arguments(listOf(a0, a1, a2, a3, a4, a5, a6), tailBlockMode)
+                 }
+                 8 -> {
+                     val a0 = this.elementAt(0).value.execute(scope)
+                     val a1 = this.elementAt(1).value.execute(scope)
+                     val a2 = this.elementAt(2).value.execute(scope)
+                     val a3 = this.elementAt(3).value.execute(scope)
+                     val a4 = this.elementAt(4).value.execute(scope)
+                     val a5 = this.elementAt(5).value.execute(scope)
+                     val a6 = this.elementAt(6).value.execute(scope)
+                     val a7 = this.elementAt(7).value.execute(scope)
+                     Arguments(listOf(a0, a1, a2, a3, a4, a5, a6, a7), tailBlockMode)
+                 }
                  else -> null
              }
              if (quick != null) return quick

lynglib/src/commonMain/kotlin/net/sergeych/lyng/ScopePool.kt

@@ -1,35 +1,12 @@
 package net.sergeych.lyng
 
 import net.sergeych.lyng.obj.Obj
-import net.sergeych.lyng.obj.ObjVoid
 
 /**
- * Simple, portable scope frame pool. JVM-first optimization; for now it uses a small
- * global deque. It is only used when [PerfFlags.SCOPE_POOL] is true.
- *
- * NOTE: This implementation is not thread-safe. It is acceptable for current single-threaded
- * script execution and JVM tests. If we need cross-thread safety later, we will introduce
- * platform-specific implementations.
+ * Expect/actual portable scope frame pool. Used only when [PerfFlags.SCOPE_POOL] is true.
+ * JVM actual provides a ThreadLocal-backed pool; other targets may use a simple global deque.
  */
-object ScopePool {
-    private const val MAX_POOL_SIZE = 64
-    private val pool = ArrayDeque<Scope>(MAX_POOL_SIZE)
-
-    fun borrow(parent: Scope, args: Arguments, pos: Pos, thisObj: Obj): Scope {
-        val s = if (pool.isNotEmpty()) pool.removeLast() else Scope(parent, args, pos, thisObj)
-        // If we reused a scope, reset its state to behave as a fresh child frame
-        if (s.parent !== parent || s.args !== args || s.pos !== pos || s.thisObj !== thisObj) {
-            s.resetForReuse(parent, args, pos, thisObj)
-        } else {
-            // Even if equal by reference, refresh frameId to guarantee uniqueness
-            s.frameId = nextFrameId()
-        }
-        return s
-    }
-
-    fun release(scope: Scope) {
-        // Scrub sensitive references to avoid accidental retention
-        scope.resetForReuse(parent = null, args = Arguments.EMPTY, pos = Pos.builtIn, thisObj = ObjVoid)
-        if (pool.size < MAX_POOL_SIZE) pool.addLast(scope)
-    }
+expect object ScopePool {
+    fun borrow(parent: Scope, args: Arguments, pos: Pos, thisObj: Obj): Scope
+    fun release(scope: Scope)
 }

lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/Obj.kt

@@ -304,7 +304,10 @@ open class Obj {
     }
 
     fun autoInstanceScope(parent: Scope): Scope {
-        val scope = parent.createChildScope(newThisObj = this, args = parent.args)
+        // Create a stable instance scope whose parent is the provided parent scope directly,
+        // not a transient child that could be pooled and reset. This preserves proper name
+        // resolution (e.g., stdlib functions like sqrt) even when call frame pooling is enabled.
+        val scope = Scope(parent, parent.args, parent.pos, this)
         for (m in objClass.members) {
             scope.objects[m.key] = m.value
         }

lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjClass.kt

@@ -68,7 +68,11 @@ open class ObjClass(
 
     override suspend fun callOn(scope: Scope): Obj {
         val instance = ObjInstance(this)
-        instance.instanceScope = scope.createChildScope(newThisObj = instance, args = scope.args)
+        // Avoid capturing a transient (pooled) call frame as the parent of the instance scope.
+        // Bind instance scope to the caller's parent chain directly so name resolution (e.g., stdlib like sqrt)
+        // remains stable even when call frames are pooled and reused.
+        val stableParent = scope.parent
+        instance.instanceScope = Scope(stableParent, scope.args, scope.pos, instance)
         if (instanceConstructor != null) {
             instanceConstructor!!.execute(instance.instanceScope)
         }

lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjDeferred.kt

@@ -37,7 +37,9 @@ open class ObjDeferred(val deferred: Deferred<Obj>): Obj() {
                 thisAs<ObjDeferred>().deferred.isCompleted.toObj()
             }
             addFn("isActive") {
-                thisAs<ObjDeferred>().deferred.isActive.toObj()
+                val d = thisAs<ObjDeferred>().deferred
+                // Cross-engine tolerant: treat any not-yet-completed deferred as active.
+                (!d.isCompleted).toObj()
             }
             addFn("isCancelled") {
                 thisAs<ObjDeferred>().deferred.isCancelled.toObj()

lynglib/src/jsMain/kotlin/net/sergeych/lyng/ScopePoolJs.kt

@@ -0,0 +1,27 @@
+package net.sergeych.lyng
+
+import net.sergeych.lyng.obj.Obj
+import net.sergeych.lyng.obj.ObjVoid
+
+/**
+ * JS actual: simple global deque pool (single-threaded runtime).
+ */
+actual object ScopePool {
+    private const val MAX_POOL_SIZE = 64
+    private val pool = ArrayDeque<Scope>(MAX_POOL_SIZE)
+
+    actual fun borrow(parent: Scope, args: Arguments, pos: Pos, thisObj: Obj): Scope {
+        val s = if (pool.isNotEmpty()) pool.removeLast() else Scope(parent, args, pos, thisObj)
+        if (s.parent !== parent || s.args !== args || s.pos !== pos || s.thisObj !== thisObj) {
+            s.resetForReuse(parent, args, pos, thisObj)
+        } else {
+            s.frameId = nextFrameId()
+        }
+        return s
+    }
+
+    actual fun release(scope: Scope) {
+        scope.resetForReuse(parent = null, args = Arguments.EMPTY, pos = Pos.builtIn, thisObj = ObjVoid)
+        if (pool.size < MAX_POOL_SIZE) pool.addLast(scope)
+    }
+}

lynglib/src/jvmMain/kotlin/net/sergeych/lyng/PerfDefaults.jvm.kt

@@ -6,7 +6,7 @@ actual object PerfDefaults {
 
     actual val ARG_BUILDER: Boolean = true
     actual val SKIP_ARGS_ON_NULL_RECEIVER: Boolean = true
-    actual val SCOPE_POOL: Boolean = false
+    actual val SCOPE_POOL: Boolean = true
 
     actual val FIELD_PIC: Boolean = true
     actual val METHOD_PIC: Boolean = true

lynglib/src/jvmMain/kotlin/net/sergeych/lyng/ScopePoolJvm.kt

@@ -0,0 +1,30 @@
+package net.sergeych.lyng
+
+import net.sergeych.lyng.obj.Obj
+import net.sergeych.lyng.obj.ObjVoid
+
+/**
+ * JVM actual: per-thread scope frame pool backed by ThreadLocal.
+ * Used only when [PerfFlags.SCOPE_POOL] is true.
+ */
+actual object ScopePool {
+    private const val MAX_POOL_SIZE = 64
+    private val threadLocalPool: ThreadLocal<ArrayDeque<Scope>> = ThreadLocal.withInitial {
+        ArrayDeque<Scope>(MAX_POOL_SIZE)
+    }
+
+    actual fun borrow(parent: Scope, args: Arguments, pos: Pos, thisObj: Obj): Scope {
+        val pool = threadLocalPool.get()
+        val s = if (pool.isNotEmpty()) pool.removeLast() else Scope(parent, args, pos, thisObj)
+        // Always reset state on borrow to guarantee fresh-frame semantics
+        s.resetForReuse(parent, args, pos, thisObj)
+        return s
+    }
+
+    actual fun release(scope: Scope) {
+        val pool = threadLocalPool.get()
+        // Scrub sensitive references to avoid accidental retention
+        scope.resetForReuse(parent = null, args = Arguments.EMPTY, pos = Pos.builtIn, thisObj = ObjVoid)
+        if (pool.size < MAX_POOL_SIZE) pool.addLast(scope)
+    }
+}

lynglib/src/jvmTest/kotlin/BookTest.kt

@@ -206,6 +206,10 @@ suspend fun DocTest.test(_scope: Scope? = null) {
             expectedResult != result
         ) {
             System.err.println("\nfailed: ${this.detailedString}")
+            System.err.println("[DEBUG_LOG] expectedOutput=\n${expectedOutput}")
+            System.err.println("[DEBUG_LOG] actualOutput=\n${collectedOutput}")
+            System.err.println("[DEBUG_LOG] expectedResult=${expectedResult}")
+            System.err.println("[DEBUG_LOG] actualResult=${result}")
         }
         error?.let {
             fail(it.message, it)

lynglib/src/jvmTest/kotlin/ConcurrencyCallBenchmarkTest.kt

@@ -0,0 +1,66 @@
+/*
+ * Multithreaded benchmark to quantify SCOPE_POOL speedup on JVM.
+ */
+
+import kotlinx.coroutines.*
+import net.sergeych.lyng.PerfFlags
+import net.sergeych.lyng.Scope
+import net.sergeych.lyng.obj.ObjInt
+import kotlin.math.max
+import kotlin.math.min
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+class ConcurrencyCallBenchmarkTest {
+
+    private suspend fun parallelEval(workers: Int, script: String): List<Long> = coroutineScope {
+        (0 until workers).map { async { (Scope().eval(script) as ObjInt).value } }.awaitAll()
+    }
+
+    @Test
+    fun benchmark_multithread_calls_off_on() = runBlocking {
+        val cpu = Runtime.getRuntime().availableProcessors()
+        val workers = min(max(2, cpu), 8)
+        val iterations = 15_000 // per worker; keep CI fast
+        val script = """
+            fun f0() { 1 }
+            fun f1(a) { a }
+            fun f2(a,b) { a + b }
+            fun f3(a,b,c) { a + b + c }
+            fun f4(a,b,c,d) { a + b + c + d }
+            var s = 0
+            var i = 0
+            while (i < $iterations) {
+                s = s + f0()
+                s = s + f1(1)
+                s = s + f2(1, 1)
+                s = s + f3(1, 1, 1)
+                s = s + f4(1, 1, 1, 1)
+                i = i + 1
+            }
+            s
+        """.trimIndent()
+        val expected = (1 + 1 + 2 + 3 + 4).toLong() * iterations
+
+        // OFF
+        PerfFlags.SCOPE_POOL = false
+        val t0 = System.nanoTime()
+        val off = withContext(Dispatchers.Default) { parallelEval(workers, script) }
+        val t1 = System.nanoTime()
+        // ON
+        PerfFlags.SCOPE_POOL = true
+        val t2 = System.nanoTime()
+        val on = withContext(Dispatchers.Default) { parallelEval(workers, script) }
+        val t3 = System.nanoTime()
+        // reset
+        PerfFlags.SCOPE_POOL = false
+
+        off.forEach { assertEquals(expected, it) }
+        on.forEach { assertEquals(expected, it) }
+
+        val offMs = (t1 - t0) / 1_000_000.0
+        val onMs = (t3 - t2) / 1_000_000.0
+        val speedup = offMs / onMs
+        println("[DEBUG_LOG] [BENCH] ConcurrencyCallBenchmark workers=$workers iters=$iterations each: OFF=${"%.3f".format(offMs)} ms, ON=${"%.3f".format(onMs)} ms, speedup=${"%.2f".format(speedup)}x")
+    }
+}

lynglib/src/jvmTest/kotlin/MultiThreadPoolingStressJvmTest.kt

@@ -0,0 +1,97 @@
+/*
+ * Multithreaded stress tests for ScopePool on JVM.
+ */
+
+import kotlinx.coroutines.*
+import net.sergeych.lyng.PerfFlags
+import net.sergeych.lyng.Scope
+import net.sergeych.lyng.obj.ObjInt
+import kotlin.math.max
+import kotlin.math.min
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+class MultiThreadPoolingStressJvmTest {
+
+    private suspend fun parallelEval(workers: Int, block: suspend (Int) -> Long): List<Long> = coroutineScope {
+        (0 until workers).map { w -> async { block(w) } }.awaitAll()
+    }
+
+    @Test
+    fun parallel_shallow_calls_correct_off_on() = runBlocking {
+        val cpu = Runtime.getRuntime().availableProcessors()
+        val workers = min(max(2, cpu), 8)
+        val iterations = 25_000 // keep CI reasonable
+        val script = """
+            fun f0(a){ a }
+            fun f1(a,b){ a + b }
+            fun f2(a,b,c){ a + b + c }
+            var s = 0
+            var i = 0
+            while(i < $iterations){
+                s = s + f0(1)
+                s = s + f1(1,1)
+                s = s + f2(1,1,1)
+                i = i + 1
+            }
+            s
+        """.trimIndent()
+
+        fun expected() = (1 + 2 + 3).toLong() * iterations
+
+        // OFF
+        PerfFlags.SCOPE_POOL = false
+        val offResults = withContext(Dispatchers.Default) {
+            parallelEval(workers) {
+                val r = (Scope().eval(script) as ObjInt).value
+                r
+            }
+        }
+        // ON
+        PerfFlags.SCOPE_POOL = true
+        val onResults = withContext(Dispatchers.Default) {
+            parallelEval(workers) {
+                val r = (Scope().eval(script) as ObjInt).value
+                r
+            }
+        }
+        // reset
+        PerfFlags.SCOPE_POOL = false
+
+        val exp = expected()
+        offResults.forEach { assertEquals(exp, it) }
+        onResults.forEach { assertEquals(exp, it) }
+    }
+
+    @Test
+    fun parallel_recursion_correct_off_on() = runBlocking {
+        val cpu = Runtime.getRuntime().availableProcessors()
+        val workers = min(max(2, cpu), 8)
+        val depth = 12
+        val script = """
+            fun fact(x){ if(x <= 1) 1 else x * fact(x-1) }
+            fact($depth)
+        """.trimIndent()
+        val expected = (1..depth).fold(1L){a,b->a*b}
+
+        // OFF
+        PerfFlags.SCOPE_POOL = false
+        val offResults = withContext(Dispatchers.Default) {
+            parallelEval(workers) {
+                (Scope().eval(script) as ObjInt).value
+            }
+        }
+        // ON
+        PerfFlags.SCOPE_POOL = true
+        val onResults = withContext(Dispatchers.Default) {
+            parallelEval(workers) {
+                (Scope().eval(script) as ObjInt).value
+            }
+        }
+        // reset
+        PerfFlags.SCOPE_POOL = false
+
+        offResults.forEach { assertEquals(expected, it) }
+        onResults.forEach { assertEquals(expected, it) }
+    }
+}

lynglib/src/nativeMain/kotlin/net/sergeych/lyng/ScopePoolNative.kt

@@ -0,0 +1,27 @@
+package net.sergeych.lyng
+
+import net.sergeych.lyng.obj.Obj
+import net.sergeych.lyng.obj.ObjVoid
+
+/**
+ * Native actual: simple global deque pool. Many native targets are single-threaded by default in our setup.
+ */
+actual object ScopePool {
+    private const val MAX_POOL_SIZE = 64
+    private val pool = ArrayDeque<Scope>(MAX_POOL_SIZE)
+
+    actual fun borrow(parent: Scope, args: Arguments, pos: Pos, thisObj: Obj): Scope {
+        val s = if (pool.isNotEmpty()) pool.removeLast() else Scope(parent, args, pos, thisObj)
+        if (s.parent !== parent || s.args !== args || s.pos !== pos || s.thisObj !== thisObj) {
+            s.resetForReuse(parent, args, pos, thisObj)
+        } else {
+            s.frameId = nextFrameId()
+        }
+        return s
+    }
+
+    actual fun release(scope: Scope) {
+        scope.resetForReuse(parent = null, args = Arguments.EMPTY, pos = Pos.builtIn, thisObj = ObjVoid)
+        if (pool.size < MAX_POOL_SIZE) pool.addLast(scope)
+    }
+}

lynglib/src/wasmJsMain/kotlin/net/sergeych/lyng/ScopePoolWasm.kt

@@ -0,0 +1,27 @@
+package net.sergeych.lyng
+
+import net.sergeych.lyng.obj.Obj
+import net.sergeych.lyng.obj.ObjVoid
+
+/**
+ * Wasm/JS actual: simple global deque pool (single-threaded runtime model).
+ */
+actual object ScopePool {
+    private const val MAX_POOL_SIZE = 64
+    private val pool = ArrayDeque<Scope>(MAX_POOL_SIZE)
+
+    actual fun borrow(parent: Scope, args: Arguments, pos: Pos, thisObj: Obj): Scope {
+        val s = if (pool.isNotEmpty()) pool.removeLast() else Scope(parent, args, pos, thisObj)
+        if (s.parent !== parent || s.args !== args || s.pos !== pos || s.thisObj !== thisObj) {
+            s.resetForReuse(parent, args, pos, thisObj)
+        } else {
+            s.frameId = nextFrameId()
+        }
+        return s
+    }
+
+    actual fun release(scope: Scope) {
+        scope.resetForReuse(parent = null, args = Arguments.EMPTY, pos = Pos.builtIn, thisObj = ObjVoid)
+        if (pool.size < MAX_POOL_SIZE) pool.addLast(scope)
+    }
+}