UnsafeShuffleExternalSorter should preserve first page

5/08/31 18:41:25 WARN TaskSetManager: Lost task 16.1 in stage 316.0 (TID 32686, lon4-hadoopslave-b925.lon4.spotify.net): java.io.IOException: Unable to acquire 67108864 bytes of memory
        at org.apache.spark.shuffle.unsafe.UnsafeShuffleExternalSorter.acquireNewPageIfNecessary(UnsafeShuffleExternalSorter.java:385)
        at org.apache.spark.shuffle.unsafe.UnsafeShuffleExternalSorter.insertRecord(UnsafeShuffleExternalSorter.java:435)
        at org.apache.spark.shuffle.unsafe.UnsafeShuffleWriter.insertRecordIntoSorter(UnsafeShuffleWriter.java:246)
        at org.apache.spark.shuffle.unsafe.UnsafeShuffleWriter.write(UnsafeShuffleWriter.java:174)
        at org.apache.spark.scheduler.ShuffleMapTask.runTask(ShuffleMapTask.scala:73)
        at org.apache.spark.scheduler.ShuffleMapTask.runTask(ShuffleMapTask.scala:41)
        at org.apache.spark.scheduler.Task.run(Task.scala:88)
        at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:214)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
        at java.lang.Thread.run(Thread.java:745)