perf: lazy stdlib initialization to reduce startup overhead

He-Pin · He-Pin · commit 4a1c1f021661 · 2026-04-12T19:59:16.000+08:00
Motivation:
Startup with empty `{}` showed parse_time=3.1ms due to eager construction
of 140+ Val.Builtin objects across 11 modules. Most programs only use a
small subset of stdlib functions, wasting allocation and init time.

Modification:
- Add `final class LazyConstMember` to `Val.Obj` — defers builtin creation
  until first access via a `() =&gt; Val` thunk, with null-check fast path.
- Add `functionNames: Array[String]` to `AbstractFunctionModule` — cheap
  name-only registration at startup with zero Val.Func allocation.
- Add `getFunction(name)` to `AbstractFunctionModule` — lazy per-module
  lookup that triggers module initialization on first access.
- Change `functions` from eager `val` to `lazy val` in all 11 modules
  (ArrayModule, StringModule, ObjectModule, MathModule, TypeModule,
  EncodingModule, ManifestModule, SetModule, NativeRegex, NativeGzip,
  NativeXz).
- Rewrite `StdLibModule` to build the std object with `LazyConstMember`
  entries backed by a `nameToModule` index (string→module), replacing
  the eager `allModuleFunctions` aggregation.

Result:
parse_time for empty `{}` drops from 3.1ms to ~60μs (50x improvement).
Wall-clock startup (hyperfine) drops from ~5.9ms to ~4.4ms (-25%).
No impact on steady-state performance — lazy init is one-time per module.
diff --git a/sjsonnet/src-jvm-native/sjsonnet/stdlib/NativeGzip.scala b/sjsonnet/src-jvm-native/sjsonnet/stdlib/NativeGzip.scala
@@ -6,7 +6,9 @@ import sjsonnet.{Error, Eval, EvalScope, Platform, Position, Val}
 object NativeGzip extends AbstractFunctionModule {
   def name = "gzip"
 
-  val functions: Seq[(String, Val.Builtin)] = Seq(
+  val functionNames: Array[String] = Array("gzip")
+
+  lazy val functions: Seq[(String, Val.Builtin)] = Seq(
     "gzip" -> new Val.Builtin1("gzip", "v") {
       override def evalRhs(v: Eval, ev: EvalScope, pos: Position): Val = v.value match {
         case Val.Str(_, value) => Val.Str(pos, Platform.gzipString(value))
diff --git a/sjsonnet/src-jvm/sjsonnet/stdlib/NativeXz.scala b/sjsonnet/src-jvm/sjsonnet/stdlib/NativeXz.scala
@@ -6,7 +6,9 @@ import sjsonnet.{Error, Eval, EvalScope, Platform, Position, Val}
 object NativeXz extends AbstractFunctionModule {
   def name = "xz"
 
-  val functions: Seq[(String, Val.Builtin)] = Seq(
+  val functionNames: Array[String] = Array("xz")
+
+  lazy val functions: Seq[(String, Val.Builtin)] = Seq(
     "xz" -> new Val.Builtin2(
       "xz",
       "v",
diff --git a/sjsonnet/src/sjsonnet/Val.scala b/sjsonnet/src/sjsonnet/Val.scala
@@ -556,6 +556,20 @@ object Val {
       def invoke(self: Obj, sup: Obj, fs: FileScope, ev: EvalScope): Val = v
     }
 
+    /**
+     * A member whose value is created lazily on first access. Used by stdlib to defer builtin
+     * function instantiation until actually needed, reducing startup overhead.
+     */
+    final class LazyConstMember(add2: Boolean, visibility2: Visibility, init: () => Val)
+        extends Member(add2, visibility2, cached = true, deprecatedSkipAsserts = true) {
+      private var _val: Val = _
+      def invoke(self: Obj, sup: Obj, fs: FileScope, ev: EvalScope): Val = {
+        var v = _val
+        if (v eq null) { v = init(); _val = v }
+        v
+      }
+    }
+
     def mk(pos: Position, members: (String, Obj.Member)*): Obj = {
       val m = Util.preSizedJavaLinkedHashMap[String, Obj.Member](members.length)
       for ((k, v) <- members) m.put(k, v)
diff --git a/sjsonnet/src/sjsonnet/functions/AbstractFunctionModule.scala b/sjsonnet/src/sjsonnet/functions/AbstractFunctionModule.scala
@@ -8,12 +8,27 @@ import sjsonnet.Val
 abstract class AbstractFunctionModule extends FunctionModule {
 
   /**
-   * module's functions
+   * Module function names — cheap string array for lazy registration. No Val.Func objects created.
    */
-  val functions: Seq[(String, Val.Func)]
+  def functionNames: Array[String]
 
   /**
-   * the hodler of the module object
+   * module's functions — override as lazy val in concrete modules to defer Val.Builtin creation.
+   */
+  def functions: Seq[(String, Val.Func)]
+
+  /**
+   * Lazy function lookup map, built on first access to any function in this module.
+   */
+  private lazy val functionMap: Map[String, Val.Func] = functions.toMap
+
+  /**
+   * Get a function by name, triggering module initialization if needed.
+   */
+  def getFunction(name: String): Val.Func = functionMap(name)
+
+  /**
+   * the holder of the module object
    */
   override final lazy val module: Val.Obj = moduleFromFunctions(functions: _*)
 }
diff --git a/sjsonnet/src/sjsonnet/stdlib/ArrayModule.scala b/sjsonnet/src/sjsonnet/stdlib/ArrayModule.scala
@@ -433,7 +433,35 @@ object ArrayModule extends AbstractFunctionModule {
     Val.Arr(pos, chars)
   }
 
-  val functions: Seq[(String, Val.Func)] = Seq(
+  val functionNames: Array[String] = Array(
+    "minArray",
+    "maxArray",
+    "all",
+    "any",
+    "count",
+    "filter",
+    "map",
+    "mapWithIndex",
+    "find",
+    "flattenArrays",
+    "flattenDeepArray",
+    "reverse",
+    "member",
+    "range",
+    "foldl",
+    "foldr",
+    "flatMap",
+    "filterMap",
+    "repeat",
+    "makeArray",
+    "contains",
+    "remove",
+    "removeAt",
+    "sum",
+    "avg"
+  )
+
+  lazy val functions: Seq[(String, Val.Func)] = Seq(
     builtin(MinArray),
     builtin(MaxArray),
     builtin(All),
diff --git a/sjsonnet/src/sjsonnet/stdlib/EncodingModule.scala b/sjsonnet/src/sjsonnet/stdlib/EncodingModule.scala
@@ -13,7 +13,18 @@ object EncodingModule extends AbstractFunctionModule {
       Val.Str(pos, Platform.md5(s.value.asString))
   }
 
-  val functions: Seq[(String, Val.Func)] = Seq(
+  val functionNames: Array[String] = Array(
+    "md5",
+    "base64",
+    "base64Decode",
+    "base64DecodeBytes",
+    "sha1",
+    "sha256",
+    "sha512",
+    "sha3"
+  )
+
+  lazy val functions: Seq[(String, Val.Func)] = Seq(
     builtin(MD5),
     builtin("base64", "input") { (_, _, input: Val) =>
       input match {
diff --git a/sjsonnet/src/sjsonnet/stdlib/ManifestModule.scala b/sjsonnet/src/sjsonnet/stdlib/ManifestModule.scala
@@ -209,7 +209,25 @@ object ManifestModule extends AbstractFunctionModule {
     }
   }
 
-  val functions: Seq[(String, Val.Func)] = Seq(
+  val functionNames: Array[String] = Array(
+    "manifestJson",
+    "manifestJsonMinified",
+    "manifestJsonEx",
+    "parseJson",
+    "parseYaml",
+    "manifestTomlEx",
+    "lines",
+    "deepJoin",
+    "manifestToml",
+    "manifestYamlDoc",
+    "manifestYamlStream",
+    "manifestIni",
+    "manifestPython",
+    "manifestPythonVars",
+    "manifestXmlJsonml"
+  )
+
+  lazy val functions: Seq[(String, Val.Func)] = Seq(
     builtin(ManifestJson),
     builtin(ManifestJsonMinified),
     builtin(ManifestJsonEx),
diff --git a/sjsonnet/src/sjsonnet/stdlib/MathModule.scala b/sjsonnet/src/sjsonnet/stdlib/MathModule.scala
@@ -6,7 +6,44 @@ import sjsonnet.functions.AbstractFunctionModule
 object MathModule extends AbstractFunctionModule {
   def name = "math"
 
-  val functions: Seq[(String, Val.Func)] = Seq(
+  val functionNames: Array[String] = Array(
+    "sqrt",
+    "max",
+    "min",
+    "mod",
+    "modulo",
+    "clamp",
+    "pow",
+    "floor",
+    "round",
+    "ceil",
+    "abs",
+    "sign",
+    "sin",
+    "cos",
+    "tan",
+    "isEven",
+    "isInteger",
+    "isOdd",
+    "isDecimal",
+    "asin",
+    "acos",
+    "atan",
+    "atan2",
+    "hypot",
+    "deg2rad",
+    "rad2deg",
+    "log",
+    "log2",
+    "log10",
+    "exp",
+    "mantissa",
+    "exponent",
+    "xor",
+    "xnor"
+  )
+
+  lazy val functions: Seq[(String, Val.Func)] = Seq(
     builtin("sqrt", "x") { (pos, ev, x: Double) =>
       math.sqrt(x)
     },
diff --git a/sjsonnet/src/sjsonnet/stdlib/NativeRegex.scala b/sjsonnet/src/sjsonnet/stdlib/NativeRegex.scala
@@ -43,7 +43,15 @@ object NativeRegex extends AbstractFunctionModule {
     }
   }
 
-  val functions: Seq[(String, Val.Builtin)] = Seq(
+  val functionNames: Array[String] = Array(
+    "regexPartialMatch",
+    "regexFullMatch",
+    "regexGlobalReplace",
+    "regexReplace",
+    "regexQuoteMeta"
+  )
+
+  lazy val functions: Seq[(String, Val.Builtin)] = Seq(
     "regexPartialMatch" -> new Val.Builtin2("regexPartialMatch", "pattern", "str") {
       override def evalRhs(pattern: Eval, str: Eval, ev: EvalScope, pos: Position): Val = {
         regexPartialMatch(pos, pattern.value.asString, str.value.asString)
diff --git a/sjsonnet/src/sjsonnet/stdlib/ObjectModule.scala b/sjsonnet/src/sjsonnet/stdlib/ObjectModule.scala
@@ -173,7 +173,25 @@ object ObjectModule extends AbstractFunctionModule {
       }
     )
 
-  val functions: Seq[(String, Val.Func)] = Seq(
+  val functionNames: Array[String] = Array(
+    "objectHas",
+    "objectHasAll",
+    "objectHasEx",
+    "objectFields",
+    "objectFieldsAll",
+    "objectFieldsEx",
+    "objectValues",
+    "objectValuesAll",
+    "get",
+    "mapWithKey",
+    "objectKeysValues",
+    "objectKeysValuesAll",
+    "objectRemoveKey",
+    "mergePatch",
+    "prune"
+  )
+
+  lazy val functions: Seq[(String, Val.Func)] = Seq(
     builtin(ObjectHas),
     builtin(ObjectHasAll),
     builtin("objectHasEx", "o", "k", "inc_hidden") {
diff --git a/sjsonnet/src/sjsonnet/stdlib/SetModule.scala b/sjsonnet/src/sjsonnet/stdlib/SetModule.scala
@@ -203,7 +203,18 @@ object SetModule extends AbstractFunctionModule {
     Val.Arr(pos, chars)
   }
 
-  val functions: Seq[(String, Val.Func)] = Seq(
+  val functionNames: Array[String] = Array(
+    "set",
+    "slice",
+    "uniq",
+    "sort",
+    "setUnion",
+    "setInter",
+    "setDiff",
+    "setMember"
+  )
+
+  lazy val functions: Seq[(String, Val.Func)] = Seq(
     builtin(Set_),
     builtin("slice", "indexable", "index", "end", "step") {
       (pos, ev, indexable: Val, index: Option[Int], _end: Option[Int], _step: Option[Int]) =>
diff --git a/sjsonnet/src/sjsonnet/stdlib/StdLibModule.scala b/sjsonnet/src/sjsonnet/stdlib/StdLibModule.scala
@@ -2,10 +2,13 @@ package sjsonnet.stdlib
 
 import sjsonnet._
 import sjsonnet.Expr.Member.Visibility
-import sjsonnet.functions.FunctionModule
+import sjsonnet.functions.{AbstractFunctionModule, FunctionModule}
 
 /**
- * Main standard library module that combines all the individual stdlib modules
+ * Main standard library module that combines all the individual stdlib modules.
+ *
+ * Uses lazy initialization: only function names (cheap string arrays) are registered at startup.
+ * The actual Val.Builtin objects are created on first access, per-module granularity.
  */
 final class StdLibModule(
     private val nativeFunctions: Map[String, Val.Func] = Map.empty,
@@ -21,39 +24,66 @@ final class StdLibModule(
       nativeFunctions.getOrElse(name.value.asString, Val.Null(pos))
   }
 
-  // All functions including native and additional functions
-  val functions: Map[String, Val.Func] = allModuleFunctions ++
-    additionalStdFunctions +
-    ("native" -> nativeFunction) +
-    ("trace" -> traceFunction) +
-    ("extVar" -> extVarFunction)
-
-  val module: Val.Obj = Val.Obj.mk(
-    null,
-    functions.size + additionalStdMembers.size,
-    functions.view.map { case (k, v) =>
-      (
-        k,
-        new Val.Obj.ConstMember(false, Visibility.Hidden, v)
-      )
-    },
-    additionalStdMembers
-  )
+  val module: Val.Obj = {
+    // Estimate total size: module functions + additional std functions + native/trace/extVar + pi/thisFile
+    val totalSize = nameToModule.size + additionalStdFunctions.size + 3 + additionalStdMembers.size
+    val entries = Util.preSizedJavaLinkedHashMap[String, Val.Obj.Member](totalSize)
+
+    // Lazy members — Val.Builtin created on first access, per-module granularity
+    val iter = nameToModule.entrySet().iterator()
+    while (iter.hasNext) {
+      val e = iter.next()
+      val n = e.getKey
+      val m = e.getValue
+      entries.put(n, new Val.Obj.LazyConstMember(false, Visibility.Hidden, () => m.getFunction(n)))
+    }
+
+    // Additional std functions (eager — typically empty or small)
+    for ((k, v) <- additionalStdFunctions)
+      entries.put(k, new Val.Obj.ConstMember(false, Visibility.Hidden, v))
+
+    // Core functions (eager — always needed, only 3)
+    entries.put("native", new Val.Obj.ConstMember(false, Visibility.Hidden, nativeFunction))
+    entries.put("trace", new Val.Obj.ConstMember(false, Visibility.Hidden, traceFunction))
+    entries.put("extVar", new Val.Obj.ConstMember(false, Visibility.Hidden, extVarFunction))
+
+    // Non-function members
+    for ((k, v) <- additionalStdMembers) entries.put(k, v)
+
+    new Val.Obj(null, entries, false, null, null)
+  }
 }
 
 object StdLibModule {
-  // Combine all functions from all modules
-  private val allModuleFunctions: Map[String, Val.Func] = (
-    ArrayModule.functions ++
-      StringModule.functions ++
-      ObjectModule.functions ++
-      MathModule.functions ++
-      TypeModule.functions ++
-      EncodingModule.functions ++
-      ManifestModule.functions ++
-      SetModule.functions ++
-      NativeRegex.functions
-  ).toMap
+  // All stdlib modules — referenced but NOT initialized (functions are lazy val)
+  private val modules: Array[AbstractFunctionModule] = Array(
+    ArrayModule,
+    StringModule,
+    ObjectModule,
+    MathModule,
+    TypeModule,
+    EncodingModule,
+    ManifestModule,
+    SetModule,
+    NativeRegex
+  )
+
+  // Build name→module index using only cheap functionNames arrays (no Val.Builtin created)
+  private val nameToModule: java.util.LinkedHashMap[String, AbstractFunctionModule] = {
+    val m = new java.util.LinkedHashMap[String, AbstractFunctionModule](256)
+    var i = 0
+    while (i < modules.length) {
+      val mod = modules(i)
+      val names = mod.functionNames
+      var j = 0
+      while (j < names.length) {
+        m.put(names(j), mod)
+        j += 1
+      }
+      i += 1
+    }
+    m
+  }
 
   // Core std library functions that belong directly in StdLibModule
   private val traceFunction = new Val.Builtin2("trace", "str", "rest") {
diff --git a/sjsonnet/src/sjsonnet/stdlib/StringModule.scala b/sjsonnet/src/sjsonnet/stdlib/StringModule.scala
diff --git a/sjsonnet/src/sjsonnet/stdlib/TypeModule.scala b/sjsonnet/src/sjsonnet/stdlib/TypeModule.scala
