diff options
-rw-r--r-- | src/library/scala/collection/LinearSeqLike.scala | 14 | ||||
-rw-r--r-- | test/junit/scala/collection/immutable/ListTest.scala | 49 |
2 files changed, 59 insertions, 4 deletions
diff --git a/src/library/scala/collection/LinearSeqLike.scala b/src/library/scala/collection/LinearSeqLike.scala index ff7985bf0d..6fb452797e 100644 --- a/src/library/scala/collection/LinearSeqLike.scala +++ b/src/library/scala/collection/LinearSeqLike.scala @@ -58,12 +58,18 @@ trait LinearSeqLike[+A, +Repr <: LinearSeqLike[A, Repr]] extends SeqLike[A, Repr val result = these.head; these = these.tail; result } else Iterator.empty.next() - /** Have to clear `these` so the iterator is exhausted like - * it would be without the optimization. - */ override def toList: List[A] = { + /* Have to clear `these` so the iterator is exhausted like + * it would be without the optimization. + * + * Calling "newBuilder.result()" in toList method + * prevents original seq from garbage collection, + * so we use these.take(0) here. + * + * Check SI-8924 for details + */ val xs = these.toList - these = newBuilder.result() + these = these.take(0) xs } } diff --git a/test/junit/scala/collection/immutable/ListTest.scala b/test/junit/scala/collection/immutable/ListTest.scala new file mode 100644 index 0000000000..1006801029 --- /dev/null +++ b/test/junit/scala/collection/immutable/ListTest.scala @@ -0,0 +1,49 @@ +package scala.collection.immutable + +import org.junit.{Assert, Test} +import org.junit.runner.RunWith +import org.junit.runners.JUnit4 + +import scala.ref.WeakReference + +@RunWith(classOf[JUnit4]) +class ListTest { + /** + * Test that empty iterator does not hold reference + * to complete List + */ + @Test + def testIteratorGC(): Unit = { + var num = 0 + var emptyIterators = Seq.empty[(Iterator[Int], WeakReference[List[Int]])] + + do { + val list = List.fill(10000)(num) + val ref = WeakReference(list) + + val i = list.iterator + + while (i.hasNext) i.next() + + emptyIterators = (i, ref) +: emptyIterators + + num+=1 + } while (emptyIterators.forall(_._2.get.isDefined) && num<1000) + + // check something is result to protect from JIT optimizations + for ((i, _) <- emptyIterators) { + Assert.assertTrue(i.isEmpty) + } + + // await gc up to ~5 seconds + var forceLoops = 50 + while (emptyIterators.forall(_._2.get.isDefined) && forceLoops>0) { + System.gc() + Thread.sleep(100) + forceLoops -= 1 + } + + // real assertion + Assert.assertTrue(emptyIterators.exists(_._2.get.isEmpty)) + } +} |