SI-7336 - Link flatMapped promises to avoid memory leaks

1 files changed, 31 insertions, 0 deletions

diff --git a/test/files/run/t7336.scala b/test/files/run/t7336.scala
new file mode 100644
index 0000000000..ace83f2c1f
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+++ b/test/files/run/t7336.scala
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+import scala.concurrent.Await
+import scala.concurrent.ExecutionContext.Implicits.global
+import scala.concurrent.Future
+import scala.concurrent.duration.Duration
+
+/** This test uses recursive calls to Future.flatMap to create arrays whose
+ *  combined size is slightly greater than the JVM heap size. A previous
+ *  implementation of Future.flatMap would retain references to each array,
+ *  resulting in a speedy OutOfMemoryError. Now, each array should be freed soon
+ *  after it is created and the test should complete without problems.
+ */
+object Test {  
+  def main(args: Array[String]) {
+    def loop(i: Int, arraySize: Int): Future[Unit] = {
+      val array = new Array[Byte](arraySize)
+      Future.successful(i).flatMap { i =>
+        if (i == 0) {
+          Future.successful(())
+        } else {
+          array.size // Force closure to refer to array
+          loop(i - 1, arraySize)
+        }
+
+      }
+    }
+
+    val arraySize = 1000000
+    val tooManyArrays = (Runtime.getRuntime().totalMemory() / arraySize).toInt + 1
+    Await.ready(loop(tooManyArrays, arraySize), Duration.Inf)
+  }
+}
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