spark 1.6.3 stuck when union rdd - hadoop

Question

I want union two RDDs, one from RDBMS and one from hdfs.
It work fine when the hdfs file was not exists. And when it's exists, and union the two RDDs. Spark will stuck.
the log:
16/11/24 20:01:29 INFO ShuffleBlockFetcherIterator: Getting 2 non-empty blocks out of 200 blocks
16/11/24 20:01:29 INFO ShuffleBlockFetcherIterator: Started 0 remote fetches in 1 ms
16/11/24 20:01:29 INFO ShuffleBlockFetcherIterator: Getting 1 non-empty blocks out of 1 blocks
16/11/24 20:01:29 INFO ShuffleBlockFetcherIterator: Started 0 remote fetches in 0 ms
16/11/24 20:01:29 INFO Executor: Finished task 2.0 in stage 5.0 (TID 409). 2074 bytes result sent to driver
16/11/24 20:01:29 INFO TaskSetManager: Finished task 2.0 in stage 5.0 (TID 409) in 76 ms on localhost (1/3)
stop at here.
the code:
val allUserAction = if (exists) {
val textFile = sc.textFile(historyHDFSFilePath).map { line =>
//val textFile = sc.textFile("file:///Volumes/disk02/Desktop/part-00000").map { line =>
val values = line.split(",")
if (values.length == 13) {
(values(0).toLong, (values(1), values(2).toLong, values(3).toLong,
values(4).toInt, values(5).toLong, values(6).toInt, values(7).toBoolean, false, values(8).toBoolean,
values(9).toBoolean, values(10).toBoolean, values(11).toInt, values(12).toInt))
} else {
(0L, ("", 0L, 0L, 0, 0L, 0, false, false, false, false, false, 0, 0))
}
}
textFile.union(registerUserSourceWithOp)
} else {
registerUserSourceWithOp
}.cache()
allUserAction.collect().foreach(println)
If I copy the file from hdfs to local machine. and read from it. it work fine.
How to fix it. THX~