From fb43ec8dc28625c929beaf28767a955388700d0d Mon Sep 17 00:00:00 2001
From: Jason Zaugg <jzaugg@gmail.com>
Date: Thu, 5 Sep 2013 15:27:15 +0200
Subject: SI-7814 Avoid init cycle between Predef, `package`, ScalaRuntime

Not every application will force these in a single thread; we
have to do our best to avoid cycles between them.

The enclosed test was failing every time before the change.

This commit breaks the cycle by avoiding computing `tupleNames`
in the constructor of `ScalaRuntime`. The new version has the
added benefit of including specialized tuple subclasses, which
is verified with a unit test for `isTuple`.

Are there more of these lurking? It seems likely. I'm more than
a little concerned about the way the `ControlThrowable` fires up
`scala.SystemProperties` to check whether or not to suppress
stack traces; there is already an ugly hack in place:

    object NoStackTrace {
      final def noSuppression = _noSuppression

      // two-stage init to make checkinit happy,
      // since sys.SystemProperties.noTraceSupression.value
      // calls back into NoStackTrace.noSuppression
      final private var _noSuppression = false
      _noSuppression = sys.SystemProperties.noTraceSupression.value
    }
---
 test/files/run/predef-cycle.scala | 71 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 71 insertions(+)
 create mode 100644 test/files/run/predef-cycle.scala

(limited to 'test/files/run/predef-cycle.scala')

diff --git a/test/files/run/predef-cycle.scala b/test/files/run/predef-cycle.scala
new file mode 100644
index 0000000000..ab147688bc
--- /dev/null
+++ b/test/files/run/predef-cycle.scala
@@ -0,0 +1,71 @@
+class Force {
+	val t1 = new Thread {
+    override def run() {
+      scala.`package`
+    }
+  }
+  val t2 = new Thread {
+    override def run() {
+      scala.Predef
+    }
+  }
+  t1.start()
+  t2.start()
+  t1.join()
+  t2.join()
+}
+
+object Test {
+  def main(args: Array[String]) {
+     new Force()
+  }
+}
+
+/* Was deadlocking:
+"Thread-2" prio=5 tid=7f9637268000 nid=0x119601000 in Object.wait() [119600000]
+   java.lang.Thread.State: RUNNABLE
+  at scala.Predef$.<init>(Predef.scala:90)
+  at scala.Predef$.<clinit>(Predef.scala)
+  at Force$$anon$2.run(predef-cycle.scala:10)
+
+"Thread-1" prio=5 tid=7f9637267800 nid=0x1194fe000 in Object.wait() [1194fb000]
+   java.lang.Thread.State: RUNNABLE
+  at scala.collection.immutable.Set$Set4.$plus(Set.scala:127)
+  at scala.collection.immutable.Set$Set4.$plus(Set.scala:121)
+  at scala.collection.mutable.SetBuilder.$plus$eq(SetBuilder.scala:24)
+  at scala.collection.mutable.SetBuilder.$plus$eq(SetBuilder.scala:22)
+  at scala.collection.generic.Growable$$anonfun$$plus$plus$eq$1.apply(Growable.scala:48)
+  at scala.collection.generic.Growable$$anonfun$$plus$plus$eq$1.apply(Growable.scala:48)
+  at scala.collection.immutable.List.foreach(List.scala:318)
+  at scala.collection.generic.Growable$class.$plus$plus$eq(Growable.scala:48)
+  at scala.collection.mutable.SetBuilder.$plus$plus$eq(SetBuilder.scala:22)
+  at scala.collection.TraversableLike$class.to(TraversableLike.scala:629)
+  at scala.collection.AbstractTraversable.to(Traversable.scala:105)
+  at scala.collection.TraversableOnce$class.toSet(TraversableOnce.scala:267)
+  at scala.collection.AbstractTraversable.toSet(Traversable.scala:105)
+  at scala.runtime.ScalaRunTime$.<init>(ScalaRunTime.scala:50)
+  at scala.runtime.ScalaRunTime$.<clinit>(ScalaRunTime.scala)
+  at scala.collection.mutable.HashTable$HashUtils$class.elemHashCode(HashTable.scala)
+  at scala.collection.mutable.HashMap.elemHashCode(HashMap.scala:39)
+  at scala.collection.mutable.HashTable$class.findOrAddEntry(HashTable.scala:161)
+  at scala.collection.mutable.HashMap.findOrAddEntry(HashMap.scala:39)
+  at scala.collection.mutable.HashMap.put(HashMap.scala:75)
+  at scala.collection.mutable.HashMap.update(HashMap.scala:80)
+  at scala.sys.SystemProperties$.addHelp(SystemProperties.scala:64)
+  at scala.sys.SystemProperties$.bool(SystemProperties.scala:68)
+  at scala.sys.SystemProperties$.noTraceSupression$lzycompute(SystemProperties.scala:80)
+  - locked <7b8b0e228> (a scala.sys.SystemProperties$)
+  at scala.sys.SystemProperties$.noTraceSupression(SystemProperties.scala:80)
+  at scala.util.control.NoStackTrace$.<init>(NoStackTrace.scala:31)
+  at scala.util.control.NoStackTrace$.<clinit>(NoStackTrace.scala)
+  at scala.util.control.NoStackTrace$class.fillInStackTrace(NoStackTrace.scala:22)
+  at scala.util.control.BreakControl.fillInStackTrace(Breaks.scala:93)
+  at java.lang.Throwable.<init>(Throwable.java:181)
+  at scala.util.control.BreakControl.<init>(Breaks.scala:93)
+  at scala.util.control.Breaks.<init>(Breaks.scala:28)
+  at scala.collection.Traversable$.<init>(Traversable.scala:96)
+  at scala.collection.Traversable$.<clinit>(Traversable.scala)
+  at scala.package$.<init>(package.scala:46)
+  at scala.package$.<clinit>(package.scala)
+  at Force$$anon$1.run(predef-cycle.scala:4)
+  */
\ No newline at end of file
-- 
cgit v1.2.3