【发布时间】：2019-03-05 17:59:58
【问题描述】：
我正在尝试使用 spark 将数据从 greenplum 读取到 HDFS。为此，我使用了 jar 文件：greenplum-spark_2.11-1.6.0.jar
应用 spark.read 如下：
val yearDF = spark.read.format("io.pivotal.greenplum.spark.GreenplumRelationProvider").option("url", "jdbc:postgresql://1.2.3.166:5432/finance?ssl=true&sslfactory=org.postgresql.ssl.NonValidatingFactory").option("server.port","8020").option("dbtable", "tablename").option("dbschema","schema").option("user", "123415").option("password", "etl_123").option("partitionColumn","je_id").option("partitions",3).load().where("period_year=2017 and period_num=12 and source_system_name='SSS'").select(splitSeq map col:_*).withColumn("flagCol", lit(0))
yearDF.write.format("csv").save("hdfs://dev/apps/hive/warehouse/header_test_data/")
当我运行上面的代码时，我得到了异常：
Exception in thread "qtp1438055710-505" java.lang.OutOfMemoryError: GC overhead limit exceeded
19/03/05 12:29:08 WARN QueuedThreadPool:
java.lang.OutOfMemoryError: GC overhead limit exceeded
19/03/05 12:29:08 WARN QueuedThreadPool: Unexpected thread death: org.eclipse.jetty.util.thread.QueuedThreadPool$3@16273740 in qtp1438055710{STARTED,8<=103<=200,i=19,q=0}
19/03/05 12:36:03 ERROR Executor: Exception in task 0.0 in stage 4.0 (TID 8)
org.postgresql.util.PSQLException: ERROR: error when writing data to gpfdist http://1.2.3.8:8020/spark_6ca7d983d07129f2_db5510e67a8a6f78_driver_370, quit after 2 tries (url_curl.c:584) (seg7 ip-1-3-3-196.ec2.internal:40003 pid=4062) (cdbdisp.c:1322)
at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:2310)
at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:2023)
at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:217)
at org.postgresql.jdbc.PgStatement.execute(PgStatement.java:421)
at org.postgresql.jdbc.PgStatement.executeWithFlags(PgStatement.java:318)
at org.postgresql.jdbc.PgStatement.executeUpdate(PgStatement.java:294)
at com.zaxxer.hikari.pool.ProxyStatement.executeUpdate(ProxyStatement.java:120)
at com.zaxxer.hikari.pool.HikariProxyStatement.executeUpdate(HikariProxyStatement.java)
at io.pivotal.greenplum.spark.jdbc.Jdbc$$anonfun$2.apply(Jdbc.scala:81)
at io.pivotal.greenplum.spark.jdbc.Jdbc$$anonfun$2.apply(Jdbc.scala:79)
at resource.AbstractManagedResource$$anonfun$5.apply(AbstractManagedResource.scala:88)
at scala.util.control.Exception$Catch$$anonfun$either$1.apply(Exception.scala:125)
at scala.util.control.Exception$Catch$$anonfun$either$1.apply(Exception.scala:125)
at scala.util.control.Exception$Catch.apply(Exception.scala:103)
at scala.util.control.Exception$Catch.either(Exception.scala:125)
at resource.AbstractManagedResource.acquireFor(AbstractManagedResource.scala:88)
at resource.ManagedResourceOperations$class.apply(ManagedResourceOperations.scala:26)
at resource.AbstractManagedResource.apply(AbstractManagedResource.scala:50)
at resource.DeferredExtractableManagedResource$$anonfun$tried$1.apply(AbstractManagedResource.scala:33)
at scala.util.Try$.apply(Try.scala:192)
at resource.DeferredExtractableManagedResource.tried(AbstractManagedResource.scala:33)
at io.pivotal.greenplum.spark.jdbc.Jdbc$.copyTable(Jdbc.scala:83)
at io.pivotal.greenplum.spark.externaltable.GreenplumRowIterator.liftedTree1$1(GreenplumRowIterator.scala:105)
at io.pivotal.greenplum.spark.externaltable.GreenplumRowIterator.<init>(GreenplumRowIterator.scala:104)
at io.pivotal.greenplum.spark.GreenplumRDD.compute(GreenplumRDD.scala:49)
我按照官方documentation中提到的步骤应用了这些步骤
之前我使用了 jar：greenplum.jar，它工作正常，但速度较慢，因为它通过 GP Master 提取数据。
jar：greenplum-spark_2.11-1.6.0.jar 是一个连接器 jar，它使用gpfdist 协议将数据拉取到 HDFS。
异常消息中的 IP 地址也发生了变化。你可以看到IP1.2.3.166:5432变成1.2.3.8:8020和seg7 ip-1-3-3-196.ec2.internal:40003 pid=4062
使用相同数量的执行器和执行器内存，我可以使用greenplum.jar 检索数据。但是保持一切不变，只是将 jar 更改为 greenplum-spark_2.11-1.6.0.jar 只是为了面对这个异常。
我一直在尝试解决这个问题，但我根本不理解这种现象。
谁能告诉我如何解决这个问题？
【问题讨论】：