Default -Xmixin-force-forwarders to true #5429

lrytz · 2016-09-28T14:15:49Z

Also eliminates the warning when a mixin forwarder cannot be implemented because the target method is a java-defined default method in an interface that is not a direct parent of the class.

Adds some test cases, and fixes scala/scala-dev#224.

Discussion Summary

Since #5085, classes inheriting default methods no longer get a forwarder method that delegates to the default method (except in a few corner cases, like trait methods overriding class methods). The JVMs method resolution will pick the correct method.

This PR reverts that change.

We realized that missing forwarders cause a performance regression in startup time (www.scala-lang.org/blog/2016/07/08/trait-method-performance.html). Further benchmark numbers are available in comments in this PR. In summary:

Startup is slower without forwarders
For a large program with a short running time (compiling a small file) the difference can be significant (> 40%)
Hot performance is not affected
There are probably multiple underlying causes (CHA, populating vtables), we don't have a clear picture

Two Forwarders

When trait forwarders are added, invoking a trait method involves indirection through two forwarders:

trait T { def f = 1 }
class A extends T   // generates `def f = super[T].f`

generates

class A implements T {
    public int f() { return T.f$(this); }
}
interface T {
    default public static int f$(T $this) { return $this.f(); }

    default public int f() { return 1; }
}

The reason for having a static accessor method (f$) and using it for the super calls is summarized in scala/scala-dev#228.

We could not identify any performance issues due to having two forwarders. Note that the JVM will unconditionally inline small methods (< 35 bytes) without querying any heuristics, the forwarders fall into this category.

Serialization Stability

If a class does not have an explicit @SerialVersionUID, it is computed by the VM. The computed value is sensitive to changes in the classfile that don't affect deserialization, for example adding a public method.

This means that we cannot change our strategy for mixin forwarders in a 2.12.x minor release, as it would affect serialization compatibility. So even if the performance issue with missing forwarders is fixed in a future JVM update, we need to keep the forwarders. We can re-consider for 2.13.

See also scala/scala-dev#237.

Super calls to indirect java parent interfaces cannot be emitted, an error message is emitted during SuperAccessors. The error message was missing if the super call was non-qualified, resulting in an assertion failure in the backend.

lrytz · 2016-09-30T12:36:21Z

Test failure due to a changed serialVersionUID of scala.reflect.ClassTag$GenericClassTag (there's no explicit value, the generated one changes due to the addition of mixin forwarders). The test was added in #3711 for SI-8549 to ensure serialization stability.

Looking at the class hierarchy around ClassTag and Manifest, it seems the only class that has a serialVersionUID is AnyValManifest, where the hierarchy is something like:

trait ClassTag                      // extends Serializable
|- class GenericClassTag
|- trait Manifest
   |- class ClassTypeManifest
   |- class SingletonTypeManifest
   |- ...
   |- abstract class AnyValManifest // has @SerialVersionUID
      |- class DoubleManifest
      |- ...

A comment in #3711 says

the annotation [@SerialVersionUID] can be defined up the class hierarchy

I think this comment is not correct (or it means something else than I think it means):

$ cat Test.scala
@SerialVersionUID(1L)
class A extends Serializable
class B extends A

$ scalac Test.scala && serialver -classpath .:/Users/luc/scala/scala-2.12.0-RC1/lib/scala-library.jar B
B:    private static final long serialVersionUID = -4759527637665705469L;

$ cat Test.scala
@SerialVersionUID(1L)
class A extends Serializable
class B extends A { def f = 1 }

$ scalac Test.scala && serialver -classpath .:/Users/luc/scala/scala-2.12.0-RC1/lib/scala-library.jar B
B:    private static final long serialVersionUID = -6380942902981420110L;

The @SerialVersionUID annotation on AnyValManifest was added in the same PR (#3711 / e7ab41e), probably with the intention to have a stable value for all subclasses.

I think the right solution here is to add explicit @SerialVersionUID annotations to all concrete Manifest / ClassTag subclasses.

adriaanm · 2016-09-30T18:24:08Z

LGTM

Looking at the class hierarchy around ClassTag and Manifest, the only class that had a serialVersionUID is AnyValManifest, where the hierarchy is something like: trait ClassTag // extends Serializable |- class GenericClassTag |- trait Manifest |- class ClassTypeManifest |- class SingletonTypeManifest |- ... |- abstract class AnyValManifest // has SerialVersionUID |- class DoubleManifest |- ... Note that AnyValManifest is an abstract class, so the SerialVersionUID annotation does not help there. This commit adds explicit SerialVersionUID annotations to (hopefully) all subclasses of ClassTag, to make sure they are stable under compatible changes (such as changing -Xmixin-force-forwarders).

lrytz · 2016-09-30T20:28:11Z

The SerialVersionUID test failed for Set$EmptySet$ now. I patched it up, but the way we handle this annotation in the std lib is really ad-hoc..

Also eliminates the warning when a mixin forwarder cannot be implemented because the target method is a java-defined default method in an interface that is not a direct parent of the class. The test t5148 is moved to neg, as expected: It was moved to pos when disabling mixin forwarders in 33e7106. Same for the changed error message in t4749.

Recovered and adapted some test cases for super calls from scala#5415

adriaanm · 2016-09-30T23:11:41Z

rebased with update to t8549 (git diff ffc8e3e..0e0614c):

diff --git a/test/files/run/t8549.scala b/test/files/run/t8549.scala
index 2bf648f..7ec3635 100644
--- a/test/files/run/t8549.scala
+++ b/test/files/run/t8549.scala
@@ -79,7 +79,7 @@ object Test extends App {
     }
   }

-  // Generated on 20160930-19:54:01 with Scala version 2.12.0-local-d86377e)
+  // Generated on 20160930-16:09:23 with Scala version 2.12.0-local-ffc8e3e)
   overwrite.foreach(updateComment)

   check(Some(1))("rO0ABXNyAApzY2FsYS5Tb21lESLyaV6hi3QCAAFMAAV2YWx1ZXQAEkxqYXZhL2xhbmcvT2JqZWN0O3hyAAxzY2FsYS5PcHRpb27+aTf92w5mdAIAAHhwc3IAEWphdmEubGFuZy5JbnRlZ2VyEuKgpPeBhzgCAAFJAAV2YWx1ZXhyABBqYXZhLmxhbmcuTnVtYmVyhqyVHQuU4IsCAAB4cAAAAAE=")
@@ -163,7 +163,7 @@ object Test extends App {
   // TODO SI-8576 Uninitialized field: IndexedSeqLike.scala: 56
   // check(immutable.Stream(1, 2, 3))( "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")

-  check(immutable.TreeSet[Int]())(   "rO0ABXNyACJzY2FsYS5jb2xsZWN0aW9uLmltbXV0YWJsZS5UcmVlU2V0sRdVIDjbWAsCAAJMAAhvcmRlcmluZ3QAFUxzY2FsYS9tYXRoL09yZGVyaW5nO0wABHRyZWV0AC5Mc2NhbGEvY29sbGVjdGlvbi9pbW11dGFibGUvUmVkQmxhY2tUcmVlJFRyZWU7eHBzcgAYc2NhbGEubWF0aC5PcmRlcmluZyRJbnQkKTb4nP6aAqoCAAB4cHA=")
+  check(immutable.TreeSet[Int]())(   "rO0ABXNyACJzY2FsYS5jb2xsZWN0aW9uLmltbXV0YWJsZS5UcmVlU2V0sRdVIDjbWAsCAAJMAAhvcmRlcmluZ3QAFUxzY2FsYS9tYXRoL09yZGVyaW5nO0wABHRyZWV0AC5Mc2NhbGEvY29sbGVjdGlvbi9pbW11dGFibGUvUmVkQmxhY2tUcmVlJFRyZWU7eHBzcgAYc2NhbGEubWF0aC5PcmRlcmluZyRJbnQk8u7cgruVzucCAAB4cHA=")

   // TODO SI-8576 unstable under -Xcheckinit
   // check(immutable.TreeSet(1, 2, 3))( "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")
@@ -179,12 +179,12 @@ object Test extends App {
   check(mutable.HashMap())( "rO0ABXNyACBzY2FsYS5jb2xsZWN0aW9uLm11dGFibGUuSGFzaE1hcAAAAAAAAAABAwAAeHB3DQAAAu4AAAAAAAAABAB4")
   check(mutable.HashMap(1 -> 1))( "rO0ABXNyACBzY2FsYS5jb2xsZWN0aW9uLm11dGFibGUuSGFzaE1hcAAAAAAAAAABAwAAeHB3DQAAAu4AAAABAAAABABzcgARamF2YS5sYW5nLkludGVnZXIS4qCk94GHOAIAAUkABXZhbHVleHIAEGphdmEubGFuZy5OdW1iZXKGrJUdC5TgiwIAAHhwAAAAAXEAfgAEeA==")
   check(mutable.HashSet(1, 2, 3))( "rO0ABXNyACBzY2FsYS5jb2xsZWN0aW9uLm11dGFibGUuSGFzaFNldAAAAAAAAAABAwAAeHB3DQAAAcIAAAADAAAABQBzcgARamF2YS5sYW5nLkludGVnZXIS4qCk94GHOAIAAUkABXZhbHVleHIAEGphdmEubGFuZy5OdW1iZXKGrJUdC5TgiwIAAHhwAAAAAXNxAH4AAgAAAAJzcQB+AAIAAAADeA==")
-  check(mutable.TreeMap[Int, Int]())( "rO0ABXNyACBzY2FsYS5jb2xsZWN0aW9uLm11dGFibGUuVHJlZU1hcNx8qC229ZvwAgACTAAIb3JkZXJpbmd0ABVMc2NhbGEvbWF0aC9PcmRlcmluZztMACZzY2FsYSRjb2xsZWN0aW9uJG11dGFibGUkVHJlZU1hcCQkdHJlZXQALExzY2FsYS9jb2xsZWN0aW9uL211dGFibGUvUmVkQmxhY2tUcmVlJFRyZWU7eHBzcgAYc2NhbGEubWF0aC5PcmRlcmluZyRJbnQkKTb4nP6aAqoCAAB4cHNyACpzY2FsYS5jb2xsZWN0aW9uLm11dGFibGUuUmVkQmxhY2tUcmVlJFRyZWUATKc08DWmFQIAAkkABHNpemVMAARyb290dAAsTHNjYWxhL2NvbGxlY3Rpb24vbXV0YWJsZS9SZWRCbGFja1RyZWUkTm9kZTt4cAAAAABw")
-  check(mutable.TreeMap(1 -> 1, 3 -> 6))( "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")
-  check(mutable.TreeMap(1 -> 1, 3 -> 6).range(1, 2))( "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")
-  check(mutable.TreeSet[Int]())( "rO0ABXNyACBzY2FsYS5jb2xsZWN0aW9uLm11dGFibGUuVHJlZVNldM10nxFQDpt4AgACTAAIb3JkZXJpbmd0ABVMc2NhbGEvbWF0aC9PcmRlcmluZztMACZzY2FsYSRjb2xsZWN0aW9uJG11dGFibGUkVHJlZVNldCQkdHJlZXQALExzY2FsYS9jb2xsZWN0aW9uL211dGFibGUvUmVkQmxhY2tUcmVlJFRyZWU7eHBzcgAYc2NhbGEubWF0aC5PcmRlcmluZyRJbnQkKTb4nP6aAqoCAAB4cHNyACpzY2FsYS5jb2xsZWN0aW9uLm11dGFibGUuUmVkQmxhY2tUcmVlJFRyZWUATKc08DWmFQIAAkkABHNpemVMAARyb290dAAsTHNjYWxhL2NvbGxlY3Rpb24vbXV0YWJsZS9SZWRCbGFja1RyZWUkTm9kZTt4cAAAAABw")
-  check(mutable.TreeSet(1, 3))( "rO0ABXNyACBzY2FsYS5jb2xsZWN0aW9uLm11dGFibGUuVHJlZVNldM10nxFQDpt4AgACTAAIb3JkZXJpbmd0ABVMc2NhbGEvbWF0aC9PcmRlcmluZztMACZzY2FsYSRjb2xsZWN0aW9uJG11dGFibGUkVHJlZVNldCQkdHJlZXQALExzY2FsYS9jb2xsZWN0aW9uL211dGFibGUvUmVkQmxhY2tUcmVlJFRyZWU7eHBzcgAYc2NhbGEubWF0aC5PcmRlcmluZyRJbnQkKTb4nP6aAqoCAAB4cHNyACpzY2FsYS5jb2xsZWN0aW9uLm11dGFibGUuUmVkQmxhY2tUcmVlJFRyZWUATKc08DWmFQIAAkkABHNpemVMAARyb290dAAsTHNjYWxhL2NvbGxlY3Rpb24vbXV0YWJsZS9SZWRCbGFja1RyZWUkTm9kZTt4cAAAAAJzcgAqc2NhbGEuY29sbGVjdGlvbi5tdXRhYmxlLlJlZEJsYWNrVHJlZSROb2RlGxHsFtValgACAAZaAANyZWRMAANrZXl0ABJMamF2YS9sYW5nL09iamVjdDtMAARsZWZ0cQB+AAdMAAZwYXJlbnRxAH4AB0wABXJpZ2h0cQB+AAdMAAV2YWx1ZXEAfgAKeHAAc3IAEWphdmEubGFuZy5JbnRlZ2VyEuKgpPeBhzgCAAFJAAV2YWx1ZXhyABBqYXZhLmxhbmcuTnVtYmVyhqyVHQuU4IsCAAB4cAAAAAFwcHNxAH4ACQFzcQB+AAwAAAADcHEAfgALcHBw")
-  check(mutable.TreeSet(1, 3).range(1, 2))( "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")
+  check(mutable.TreeMap[Int, Int]())( "rO0ABXNyACBzY2FsYS5jb2xsZWN0aW9uLm11dGFibGUuVHJlZU1hcNx8qC229ZvwAgACTAAIb3JkZXJpbmd0ABVMc2NhbGEvbWF0aC9PcmRlcmluZztMACZzY2FsYSRjb2xsZWN0aW9uJG11dGFibGUkVHJlZU1hcCQkdHJlZXQALExzY2FsYS9jb2xsZWN0aW9uL211dGFibGUvUmVkQmxhY2tUcmVlJFRyZWU7eHBzcgAYc2NhbGEubWF0aC5PcmRlcmluZyRJbnQk8u7cgruVzucCAAB4cHNyACpzY2FsYS5jb2xsZWN0aW9uLm11dGFibGUuUmVkQmxhY2tUcmVlJFRyZWUATKc08DWmFQIAAkkABHNpemVMAARyb290dAAsTHNjYWxhL2NvbGxlY3Rpb24vbXV0YWJsZS9SZWRCbGFja1RyZWUkTm9kZTt4cAAAAABw")
+  check(mutable.TreeMap(1 -> 1, 3 -> 6))( "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")
+  check(mutable.TreeMap(1 -> 1, 3 -> 6).range(1, 2))( "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")
+  check(mutable.TreeSet[Int]())( "rO0ABXNyACBzY2FsYS5jb2xsZWN0aW9uLm11dGFibGUuVHJlZVNldM10nxFQDpt4AgACTAAIb3JkZXJpbmd0ABVMc2NhbGEvbWF0aC9PcmRlcmluZztMACZzY2FsYSRjb2xsZWN0aW9uJG11dGFibGUkVHJlZVNldCQkdHJlZXQALExzY2FsYS9jb2xsZWN0aW9uL211dGFibGUvUmVkQmxhY2tUcmVlJFRyZWU7eHBzcgAYc2NhbGEubWF0aC5PcmRlcmluZyRJbnQk8u7cgruVzucCAAB4cHNyACpzY2FsYS5jb2xsZWN0aW9uLm11dGFibGUuUmVkQmxhY2tUcmVlJFRyZWUATKc08DWmFQIAAkkABHNpemVMAARyb290dAAsTHNjYWxhL2NvbGxlY3Rpb24vbXV0YWJsZS9SZWRCbGFja1RyZWUkTm9kZTt4cAAAAABw")
+  check(mutable.TreeSet(1, 3))( "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")
+  check(mutable.TreeSet(1, 3).range(1, 2))( "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")
   // TODO SI-8576 Uninitialized field under -Xcheckinit
   // check(new mutable.History())( "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")
   check(mutable.LinkedHashMap(1 -> 2))( "rO0ABXNyACZzY2FsYS5jb2xsZWN0aW9uLm11dGFibGUuTGlua2VkSGFzaE1hcAAAAAAAAAABAwAAeHB3DQAAAu4AAAABAAAABABzcgARamF2YS5sYW5nLkludGVnZXIS4qCk94GHOAIAAUkABXZhbHVleHIAEGphdmEubGFuZy5OdW1iZXKGrJUdC5TgiwIAAHhwAAAAAXNxAH4AAgAAAAJ4")

lrytz · 2016-10-01T05:21:50Z

Green now, i guess you just re-generated the test?

lrytz · 2016-10-01T07:15:43Z

Wait, you had to update the test in the "Default -Xmixin-force-forwarders to true" commit, which means that there's still some classes being tested by t8549 that change SVUID under -Xmixin-force-forwarders:ture. Instead, these classes should get the annotation.

lrytz · 2016-10-01T10:16:42Z

So this time it would be Ordering$Int$ that should get the annotation it seems. Strangely I couldn't reproduce the failure locally (i did a local bootstrap). So yeah, not sure if we should go through more of the std lib and add the annotations everywhere..

This is a reminder that changing -Xmixin-force-forwarders, even though binary compatible, is not serialization compatible.

adriaanm · 2016-10-01T14:14:28Z

This is a reminder that changing -Xmixin-force-forwarders, even though binary compatible, is not serialization compatible.

Yep :-/ Do we still commit to having it on, knowing we can't turn it off?

lrytz · 2016-10-03T09:52:15Z

I'm still in favor of the change. Do we have any guarantees in serialization compatibility? We have t8549, but it covers only a slice of the serializable classes in the sdt lib. For users, anyone relying on serialization compatibility across binary versions should be using @SVUID anyway.

adriaanm · 2016-10-03T14:42:45Z

We don't explicitly promise it because we can't mechanically check, but we
have tended to shy away from making changes that could impact
serializability.

If the performance benefit is significant, I'm on board but I don't think
we can revert it later knowing the impact on serialization.
On Mon, Oct 3, 2016 at 04:52 Lukas Rytz notifications@github.com wrote:

I'm still in favor of the change. Do we have any guarantees in
serialization compatibility? We have t8549, but it covers only a slice of
the serializable classes in the sdt lib. For users, anyone relying on
serialization compatibility across binary versions should be using
@SVUID anyway.

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lrytz · 2016-10-04T17:52:50Z

I'm going a bit further into the off-topic..

Maybe we should have an -Xlint warning for subclasses (abstract and concrete, not traits) of Serializable that don't have the @SVUID annotation?

The problem with explicit @SVUID is that it not only allows benign changes such as adding a public method to a class, but also lets problematic changes pass. For example:

@SerialVersionUID(1L)
class ArrayBuffer extends Serializable {
  private var elems = new Array[AnyRef](8)
  private def ensureCapacity(n: Int): Unit = {
    // var newSize = elems.length * 2
    // while (n >= newSize) newSize *= 2
  }
  def clear(): Unit = { elems = new Array[AnyRef](8) }
}

Now assume there's a refactoring:

@SerialVersionUID(1L)
class ArrayBuffer(initSize: Int) extends Serializable {
  assert(initSize > 1)
  def this() = this(8)
  private var elems = new Array[AnyRef](initSize)
  private def ensureCapacity(n: Int): Unit = {
    // ...
    // var newSize = elems.length * 2
    // while (n >= newSize) newSize *= 2
    // 
  }
  def clear(): Unit = { elems = new Array[AnyRef](initSize) }
}

Now if you de-serialize a stream from the first version into the second version, the initSize field will be 0. After a call to clear(), ensureCapacity will loop forever.

This is of course not a Scala-specific problem, but we don't have a way of tracking actual breaking changes in the std lib.

adriaanm · 2016-10-04T20:52:08Z

Let's spin the serialization topic of to its own scala-dev issue. Maybe we could consider assigning a SVUID that's 1:1 with the Scala binary version for all classes in the stdlib? Together with MiMa this would ensure serialization "compatibility" (somewhat trivially).

retronym · 2016-10-09T12:22:41Z

Example of our "strongly woven" family tree:

scala> def interfaceCount(cls: Class[_]) = {
  val m = collection.mutable.Map[Class[_], Int]().withDefaultValue(0)
  def loop(cls1: Class[_]) 
    cls1.getInterfaces.foreach(i => m(i) = (m(i) + 1))
    cls1.getInterfaces.foreach(loop)
    if (cls1.getSuperclass != null) loop(cls1.getSuperclass)
  }
  loop(cls)
  m
}
interfaceCount: (cls: Class[_])scala.collection.mutable.Map[Class[_],Int]

scala> println(interfaceCount(Nil.getClass).toSeq.sortBy(-_._2).mkString("\n"))
(interface scala.collection.GenTraversableOnce,75)
(interface scala.collection.Parallelizable,58)
(interface scala.collection.GenTraversableLike,58)
(interface scala.collection.generic.HasNewBuilder,32)
(interface scala.collection.GenIterableLike,26)
(interface scala.Equals,19)
(interface scala.collection.TraversableOnce,17)
(interface scala.collection.generic.FilterMonadic,17)
(interface scala.collection.TraversableLike,17)
(interface scala.collection.generic.GenericTraversableTemplate,15)
(interface scala.collection.GenTraversable,15)
(interface scala.collection.IterableLike,10)
(interface scala.collection.GenSeqLike,8)
(interface scala.collection.GenIterable,8)
(interface scala.collection.Traversable,7)
(interface scala.collection.SeqLike,5)
(interface scala.collection.Iterable,5)
(interface scala.collection.Seq,3)
(interface scala.PartialFunction,3)
(interface scala.Function1,3)
(interface scala.collection.GenSeq,3)
(interface java.io.Serializable,2)
(interface scala.collection.LinearSeqLike,2)
(interface scala.collection.immutable.Traversable,1)
(interface scala.collection.immutable.LinearSeq,1)
(interface scala.collection.immutable.Seq,1)
(interface scala.collection.LinearSeqOptimized,1)
(interface scala.collection.immutable.Iterable,1)
(interface scala.Immutable,1)
(interface scala.Serializable,1)
(interface scala.Product,1)
(interface scala.collection.LinearSeq,1)

HotSpot code involved:

http://hg.openjdk.java.net/jdk9/jdk9/hotspot/file/tip/src/share/vm/classfile/defaultMethods.cpp

retronym · 2016-10-09T12:34:02Z

This recently fixed JDK bug is in the same ballpark, but appears distinct: https://bugs.openjdk.java.net/browse/JDK-8163969

lrytz · 2016-10-09T15:41:02Z

It's an interesting thing to keep in mind, but I guess there's nothing we can do about it for RC2 - the presence / absence of mixin forwarders does not have an impact here, right?

I'll do some more benchmarks for the effects related to mixin forwarders when I get back.

lrytz · 2016-10-09T18:15:21Z

When using -XX:TieredStopAtLevel=1, i.e., disabling C2, therefore relying more on CHA, there is a difference in hot performance (with C2 enabled, hot performance was the same):

better-files

n: 1834.449 ± 8.637
y: 1893.169 ± 12.478

hello

n: 101.173 ± 0.382
y: 96.638 ± 0.361

retronym · 2016-10-09T22:44:42Z

I've lodged a bug for the HotSpot problem with default method resolution performance, I'll link it here when it appears in the tracker.

Here's an attempt to distill the problem in a Java-only test case: https://gist.github.com/retronym/ddedbadc3c764da66ffdb9a911915b40

lrytz · 2016-10-10T13:55:07Z

I did a bit of benchmarking with the debug JVM that I built on linux, with the goal of comparing the impact of the -XX:-UseCHA flag.

But it looks like a bad idea to use such a VM for benchmarking: it is extremely slow (plenty of debug code all over). For example, compiling better-files takes 11s with Oracle 1.8.0_102, but 47s with the debug VM I built (jdk8u branch).

Anyway, here are some numbers I collected on the debug VM, using 2.11.8.

hello, hot performance

default: 160.882 ± 5.780
-UseCHA: 158.800 ± 5.996

hello, cold performance

default: 9072.075 ± 354.355
-UseCHA: 6988.007 ± 212.776

better-files, hot performance

default: 1578.248 ± 140.107
-UseCHA: 1874.994 ± 47.585

better-files, cold performance

default: 32128.875 ± 653.279
-UseCHA: ~ 55000

Not sure if we can draw any conclusions here.. CHA slows down, maybe due to additional debug logging?

lrytz · 2016-10-11T10:10:08Z

Interestingly, the difference cold performance is caused mostly by forwarders in scala-library.jar.

hello, cold performance

no forwarders: 3973.261 ± 23.066
forwarders only in compiler + reflect: 3926.395 ± 34.604
forwarders only in library: 2861.180 ± 22.530
forwarders in all jars: 2808.490 ± 31.637

lrytz · 2016-10-11T15:35:24Z

One more number: when disabling JIT entirely (-Xint), the forwarders still improve performance. For compiling hello, cold performance, it's 15%:

no forwarders: 7031.654 ± 60.182
with forwarders: 6099.804 ± 24.948

If we assume that CHA is only used in the optimizers (not sure if that is true), this shows that there is some other factor at play.

Maybe this is related to method resolution, but this is just a guess.

trait T { def f = 1 }
class A extends T
class C { def g(a: A) = a.f }

In C we get an invokevirtual A.f (with or without the forwarder). If there's a forwarder, resolution should be quick (it's right there in A). The forwarder itself does:

class A implements T {
  public f()I
    ALOAD 0
    INVOKESTATIC T.f$ (LT;)I
    IRETURN
}

The lookup of the static method should be quick, too. The static accessor in T does:

interface T {
  public static synthetic f$(LT;)I
    ALOAD 0
    INVOKESPECIAL T.f ()I
    IRETURN
}

The lookup of INVOKESPECIAL T.f should also be quick, it's in the named class.

If A doesn't have a forwarder, resolving A.f is more costly, especially if A extends a large number of interfaces and f is defined somewhere high up (think: collections). We should benchmark a bit more in this area at some point.

Note that the interpreter needs to go through two forwarders, but this is still faster than the version where the default method is directly executed.

lrytz · 2016-10-11T15:44:54Z

I think we should take a decision based on the numbers we have now. (Suggestions for other benchmarks are welcome, if they can be done quickly. I guess we want to have RC2 soon.)

To summarize:

Startup is slower without forwarders
For a large program with a short running time (compiling a small file) the difference can be significant (40%)
Hot performance is not affected
There are probalby multiple underlying causes (CHA, populating vtables), we don't have a clear picture
We cannot revert in 2.12.x due to serialization compatibility

adriaanm · 2016-10-11T16:15:59Z

Since emitting the forwarders doesn't adversely affect hot performance, while substantially improving startup on current JVMs, I agree we should merge this PR. Our concern remains that this is an area where we are exposed to intricacies of the JIT and classloading, which could change in future updates, while we are bound to the choice we make now (because flipping the switch affects serialization compatibility).

retronym · 2016-10-12T00:47:12Z

LGTM

retronym · 2016-10-12T22:06:32Z

I've spun out the issue with startup performance as scala/scala-dev#243

We need this to close the loop on scala#5429.

ramkishanbetta · 2022-01-17T14:10:25Z

The SerialVersionUID test failed for Set$EmptySet$ now. I patched it up, but the way we handle this annotation in the std lib is really ad-hoc..

Well, how do one is expected to handle this as part of upgrade? Say, I serialized using scala 2.11 and saved, and deserialize in scala 2.12 post upgrade?

scala-jenkins added this to the 2.12.0-RC2 milestone Sep 28, 2016

lrytz force-pushed the sd224 branch from 700bd35 to 85613f1 Compare September 28, 2016 14:18

lrytz added 2 commits September 30, 2016 11:06

re-enable two tests (starr is up to date now)

9246348

lrytz force-pushed the sd224 branch from 85613f1 to 91327cc Compare September 30, 2016 09:06

lrytz force-pushed the sd224 branch 4 times, most recently from 893ef2f to 1b1a4e6 Compare September 30, 2016 17:56

scala-jenkins added the reviewed label Sep 30, 2016

lrytz force-pushed the sd224 branch from 1b1a4e6 to a8ab471 Compare September 30, 2016 18:35

lrytz force-pushed the sd224 branch from a8ab471 to 9fc8a72 Compare September 30, 2016 20:28

lrytz added 2 commits September 30, 2016 16:10

Test cases for super calls

550e47b

Recovered and adapted some test cases for super calls from scala#5415

adriaanm force-pushed the sd224 branch from 9fc8a72 to 550e47b Compare September 30, 2016 23:10

lrytz force-pushed the sd224 branch 2 times, most recently from 9fc8a72 to 550e47b Compare October 1, 2016 10:14

adriaanm merged commit 1e81a09 into scala:2.12.0 Oct 12, 2016

This was referenced Oct 12, 2016

Decide on default value for -Xmixin-force-forwarders in 2.12.0 scala/scala-dev#231

Closed

Crash with supercall to Java interface scala/scala-dev#224

Closed

retronym added a commit to retronym/scala that referenced this pull request Oct 13, 2016

Restarr to fix InterfaceMethodRef after closure inlining

1f5a4e2

We need this to close the loop on scala#5429.

retronym added a commit to retronym/scala that referenced this pull request Oct 13, 2016

Restarr to fix InterfaceMethodRef after closure inlining

b52c591

We need this to close the loop on scala#5429.

retronym mentioned this pull request Oct 13, 2016

Restarr to fix InterfaceMethodRef after closure inlining #5457

Merged

lrytz mentioned this pull request Oct 13, 2016

Startup regression due to HotSpot JVM's population of vtables with default methods scala/scala-dev#243

Open

adriaanm added the release-notes worth highlighting in next release notes label Oct 15, 2016

adriaanm modified the milestone: 2.12.0-RC2 Oct 29, 2016

adriaanm added the 2.12 label Oct 29, 2016

scabug mentioned this pull request Apr 7, 2017

Substantial slowdown in groupBy (all collections) scala/bug#10049

Closed

lrytz deleted the sd224 branch April 12, 2017 07:53

smarter mentioned this pull request May 29, 2017

Emit mixin forwarders by default? scala/scala3#2563

Closed

lrytz mentioned this pull request Jul 18, 2017

scala/bug#5961 Add Ordering composition methods #5988

Merged

lrytz mentioned this pull request Mar 14, 2023

mark in the bytecode forwarders to Java interface default methods scala/bug#12752

Closed

Default -Xmixin-force-forwarders to true #5429

Default -Xmixin-force-forwarders to true #5429

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Two Forwarders

Serialization Stability

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