如题，stop，停止并保存检查点失败。 测试看 cancel、cancel -s 方式都成功。 cancel -s 可成功生成检查点并退出。
stop则不行，报错主要是 Could not stop with a savepoint job "1b87f308e2582f3cc0e3ccc812471201" ... Caused by: java.util.concurrent.ExecutionException: java.util.concurrent.CompletionException: org.apache.flink.runtime.checkpoint.CheckpointEx ception: Task has failed. ... Caused by: org.apache.flink.util.SerializedThrowable: org.apache.flink.runtime.checkpoint.CheckpointException: Task has failed. ... Caused by: org.apache.flink.util.SerializedThrowable: Task has failed. ... ______详细日志：
