我已经使用spark3运行了一些测试，但是我遇到了一个奇怪的问题。阶段将随机卡住，然后孔应用程序将不会生成新任务，并且驱动程序将记录npe。
spark版本：3.0.1
问题代码，例如。

val df = spark.sql("select *,b.name from a join (select * from b) on a.id=b.id")
df.createOrReplaceTempView("c")
val df1 = spark.sql("select * from c union (select * from d) union (select * from e)")
df1.createOrReplaceTempView("f")
spark.sql("insert overwrite table test select * from f")

驱动程序日志：

20/11/20 19:24:46 ERROR netty.Inbox: Ignoring error
java.lang.NullPointerException
    at java.lang.String.length(String.java:623)
    at java.lang.AbstractStringBuilder.append(AbstractStringBuilder.java:420)
    at java.lang.StringBuilder.append(StringBuilder.java:136)
    at org.apache.spark.scheduler.TaskSetManager.$anonfun$resourceOffer$5(TaskSetManager.scala:459)
    at org.apache.spark.internal.Logging.logInfo(Logging.scala:57)
    at org.apache.spark.internal.Logging.logInfo$(Logging.scala:56)
    at org.apache.spark.scheduler.TaskSetManager.logInfo(TaskSetManager.scala:54)
    at org.apache.spark.scheduler.TaskSetManager.$anonfun$resourceOffer$2(TaskSetManager.scala:459)
    at scala.Option.map(Option.scala:230)
    at org.apache.spark.scheduler.TaskSetManager.resourceOffer(TaskSetManager.scala:417)
    at org.apache.spark.scheduler.TaskSchedulerImpl.$anonfun$resourceOfferSingleTaskSet$1(TaskSchedulerImpl.scala:351)
    at scala.collection.immutable.Range.foreach$mVc$sp(Range.scala:158)
    at org.apache.spark.scheduler.TaskSchedulerImpl.resourceOfferSingleTaskSet(TaskSchedulerImpl.scala:345)
    at org.apache.spark.scheduler.TaskSchedulerImpl.$anonfun$resourceOffers$20(TaskSchedulerImpl.scala:477)
    at org.apache.spark.scheduler.TaskSchedulerImpl.$anonfun$resourceOffers$20$adapted(TaskSchedulerImpl.scala:472)
    at scala.collection.IndexedSeqOptimized.foreach(IndexedSeqOptimized.scala:36)
    at scala.collection.IndexedSeqOptimized.foreach$(IndexedSeqOptimized.scala:33)
    at scala.collection.mutable.ArrayOps$ofRef.foreach(ArrayOps.scala:198)
    at org.apache.spark.scheduler.TaskSchedulerImpl.$anonfun$resourceOffers$16(TaskSchedulerImpl.scala:472)
    at org.apache.spark.scheduler.TaskSchedulerImpl.$anonfun$resourceOffers$16$adapted(TaskSchedulerImpl.scala:448)
    at scala.collection.mutable.ResizableArray.foreach(ResizableArray.scala:62)
    at scala.collection.mutable.ResizableArray.foreach$(ResizableArray.scala:55)
    at scala.collection.mutable.ArrayBuffer.foreach(ArrayBuffer.scala:49)
    at org.apache.spark.scheduler.TaskSchedulerImpl.resourceOffers(TaskSchedulerImpl.scala:448)
    at org.apache.spark.scheduler.cluster.CoarseGrainedSchedulerBackend$DriverEndpoint.$anonfun$makeOffers$5(CoarseGrainedSchedulerBackend.scala:328)
    at org.apache.spark.scheduler.cluster.CoarseGrainedSchedulerBackend.org$apache$spark$scheduler$cluster$CoarseGrainedSchedulerBackend$$withLock(CoarseGrainedSchedulerBackend.scala:817)
    at org.apache.spark.scheduler.cluster.CoarseGrainedSchedulerBackend$DriverEndpoint.org$apache$spark$scheduler$cluster$CoarseGrainedSchedulerBackend$DriverEndpoint$$makeOffers(CoarseGrainedSchedulerBackend.scala:320)
    at org.apache.spark.scheduler.cluster.CoarseGrainedSchedulerBackend$DriverEndpoint$$anonfun$receive$1.applyOrElse(CoarseGrainedSchedulerBackend.scala:161)
    at org.apache.spark.rpc.netty.Inbox.$anonfun$process$1(Inbox.scala:115)
    at org.apache.spark.rpc.netty.Inbox.safelyCall(Inbox.scala:203)
    at org.apache.spark.rpc.netty.Inbox.process(Inbox.scala:100)
    at org.apache.spark.rpc.netty.MessageLoop.org$apache$spark$rpc$netty$MessageLoop$$receiveLoop(MessageLoop.scala:75)
    at org.apache.spark.rpc.netty.MessageLoop$$anon$1.run(MessageLoop.scala:41)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)

这个问题是随机出现的，大约五分之一。所以我检查了Spark芯，发现里面放错了地方 org.apache.spark.scheduler.TaskSetManager 459排，这个 $host 有问题，我试试 println(host) ，然后我得到了 Some(null) 在日志中。

logInfo(s"Starting $taskName (TID $taskId, $host, executor ${info.executorId}, " +
          s"partition ${task.partitionId}, $taskLocality, ${serializedTask.limit()} bytes)")