[SPARK-19481] [REPL] [MAVEN] Avoid to leak SparkContext in Signaling.cancelOnInterrupt

## What changes were proposed in this pull request?

`Signaling.cancelOnInterrupt` leaks a SparkContext per call and it makes ReplSuite unstable.

This PR adds `SparkContext.getActive` to allow `Signaling.cancelOnInterrupt` to get the active `SparkContext` to avoid the leak.

## How was this patch tested?

Jenkins

Author: Shixiong Zhu <shixiong@databricks.com>

Closes #16825 from zsxwing/SPARK-19481.

1 files changed, 11 insertions, 9 deletions

diff --git a/repl/src/main/scala/org/apache/spark/repl/Signaling.scala b/repl/src/main/scala/org/apache/spark/repl/Signaling.scala
index 202febf144..9577e0ecaa 100644
--- a/repl/src/main/scala/org/apache/spark/repl/Signaling.scala
+++ b/repl/src/main/scala/org/apache/spark/repl/Signaling.scala
@@ -28,15 +28,17 @@ private[repl] object Signaling extends Logging {
    * when no jobs are currently running.
    * This makes it possible to interrupt a running shell job by pressing Ctrl+C.
    */
-  def cancelOnInterrupt(ctx: SparkContext): Unit = SignalUtils.register("INT") {
-    if (!ctx.statusTracker.getActiveJobIds().isEmpty) {
-      logWarning("Cancelling all active jobs, this can take a while. " +
-        "Press Ctrl+C again to exit now.")
-      ctx.cancelAllJobs()
-      true
-    } else {
-      false
-    }
+  def cancelOnInterrupt(): Unit = SignalUtils.register("INT") {
+    SparkContext.getActive.map { ctx =>
+      if (!ctx.statusTracker.getActiveJobIds().isEmpty) {
+        logWarning("Cancelling all active jobs, this can take a while. " +
+          "Press Ctrl+C again to exit now.")
+        ctx.cancelAllJobs()
+        true
+      } else {
+        false
+      }
+    }.getOrElse(false)
   }
 
 }