最近用sparksession写入hive数据时，但用hive查询统计行数报错了
select count(*) from test_20190417;错误如下：
Number of reduce tasks determined at compile time: 1
In order to change the average load for a reducer (in bytes):
set hive.exec.reducers.bytes.per.reducer=<number>
In order to limit the maximum number of reducers:
set hive.exec.reducers.max=<number>
In order to set a constant number of reducers:
set mapreduce.job.reduces=<number>
java.lang.OutOfMemoryError: GC overhead limit exceeded
at com.google.protobuf.LiteralByteString.toString(LiteralByteString.java:148)
at com.google.protobuf.ByteString.toStringUtf8(ByteString.java:572)
at org.apache.hadoop.hdfs.protocol.proto.HdfsProtos$DatanodeIDProto.getHostName(HdfsProtos.java:1840)
at org.apache.hadoop.hdfs.protocolPB.PBHelper.convert(PBHelper.java:382)
at org.apache.hadoop.hdfs.protocolPB.PBHelper.convert(PBHelper.java:646)
at org.apache.hadoop.hdfs.protocolPB.PBHelper.convert(PBHelper.java:815)
at org.apache.hadoop.hdfs.protocolPB.PBHelper.convertLocatedBlock(PBHelper.java:1276)
at org.apache.hadoop.hdfs.protocolPB.PBHelper.convert(PBHelper.java:1296)
at org.apache.hadoop.hdfs.protocolPB.PBHelper.convert(PBHelper.java:1453)
at org.apache.hadoop.hdfs.protocolPB.PBHelper.convert(PBHelper.java:1555)
at org.apache.hadoop.hdfs.protocolPB.PBHelper.convert(PBHelper.java:1566)
at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolTranslatorPB.getListing(ClientNamenodeProtocolTranslatorPB.java:581)
at sun.reflect.GeneratedMethodAccessor9.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.apache.hadoop.io.retry.RetryInvocationHandler.invokeMethod(RetryInvocationHandler.java:191)
at org.apache.hadoop.io.retry.RetryInvocationHandler.invoke(RetryInvocationHandler.java:102)
at com.sun.proxy.$Proxy17.getListing(Unknown Source)
at org.apache.hadoop.hdfs.DFSClient.listPaths(DFSClient.java:2095)
at org.apache.hadoop.hdfs.DistributedFileSystem$DirListingIterator.hasNextNoFilter(DistributedFileSystem.java:986)
at org.apache.hadoop.hdfs.DistributedFileSystem$DirListingIterator.hasNext(DistributedFileSystem.java:961)
at org.apache.hadoop.mapreduce.lib.input.FileInputFormat.singleThreadedListStatus(FileInputFormat.java:304)
at org.apache.hadoop.mapreduce.lib.input.FileInputFormat.listStatus(FileInputFormat.java:265)
at org.apache.hadoop.hive.shims.Hadoop23Shims$1.listStatus(Hadoop23Shims.java:146)
at org.apache.hadoop.mapreduce.lib.input.CombineFileInputFormat.getSplits(CombineFileInputFormat.java:216)
at org.apache.hadoop.mapred.lib.CombineFileInputFormat.getSplits(CombineFileInputFormat.java:76)
at org.apache.hadoop.hive.shims.HadoopShimsSecure$CombineFileInputFormatShim.getSplits(HadoopShimsSecure.java:309)
at org.apache.hadoop.hive.ql.io.CombineHiveInputFormat.getCombineSplits(CombineHiveInputFormat.java:470)
at org.apache.hadoop.hive.ql.io.CombineHiveInputFormat.getSplits(CombineHiveInputFormat.java:571)
at org.apache.hadoop.mapreduce.JobSubmitter.writeOldSplits(JobSubmitter.java:329)
at org.apache.hadoop.mapreduce.JobSubmitter.writeSplits(JobSubmitter.java:320)
at org.apache.hadoop.mapreduce.JobSubmitter.submitJobInternal(JobSubmitter.java:196)
FAILED: Execution Error, return code -101 from org.apache.hadoop.hive.ql.exec.mr.MapRedTask. GC overhead limit exceeded
查询资料，有说集群时间不同步的问题，我查看了集群的时间都是同步的，改过hive.optimize.sort.dynamic.partition，hive.optimize.skewjoin，hive.auto.convert.join，hive.ignore.mapjoin.hint，mapreduce.map.memory.mb，mapreduce.map.java.opts，mapreduce.reduce.memory.mb，mapreduce.reduce.java.opts等参数也还是报错，调整mapreduce.reduce.memory.mb与mapreduce.map.memory.mb会出现return code -1 from XXXXX的错误，调整另外的参数就一直是return code -101 from XXXXX的错误。
后面修改export HADOOP_HEAPSIZE=的值，也还是报错。
最后我把export HADOOP_CLIENT_OPTS="-Xmx512m HADOOP_CLIENT_OPTS"，查询就正常了