From d0de367e72ba695777cfec31d796f5972ae18601 Mon Sep 17 00:00:00 2001 From: Paul Phillips Date: Fri, 23 Nov 2012 19:40:44 -0800 Subject: Fix for SI-6706, Symbol breakage under GC. Ensure the map key and the String in the Symbol are the same reference by removing the old key before updating the map with the new key -> symbol relation. --- src/library/scala/Symbol.scala | 5 +++++ test/files/run/t6706.scala | 14 ++++++++++++++ 2 files changed, 19 insertions(+) create mode 100644 test/files/run/t6706.scala diff --git a/src/library/scala/Symbol.scala b/src/library/scala/Symbol.scala index 723c05a30c..4fead7a50c 100644 --- a/src/library/scala/Symbol.scala +++ b/src/library/scala/Symbol.scala @@ -69,6 +69,11 @@ private[scala] abstract class UniquenessCache[K, V >: Null] val res = cached() if (res != null) res else { + // If we don't remove the old String key from the map, we can + // wind up with one String as the key and a different String as + // as the name field in the Symbol, which can lead to surprising + // GC behavior and duplicate Symbols. See SI-6706. + map remove name val sym = valueFromKey(name) map.put(name, new WeakReference(sym)) sym diff --git a/test/files/run/t6706.scala b/test/files/run/t6706.scala new file mode 100644 index 0000000000..905494ca8d --- /dev/null +++ b/test/files/run/t6706.scala @@ -0,0 +1,14 @@ +object Test { + var name = "foo" + 1 + var s1 = Symbol(name) + s1 = null + System.gc + val s2 = Symbol("foo1") + name = null + System.gc + val s3 = Symbol("foo1") + + def main(args: Array[String]): Unit = { + assert(s2 eq s3, ((s2, System.identityHashCode(s2), s3, System.identityHashCode(s3)))) + } +} -- cgit v1.2.3