开发中遇到的一些问题

1.StackOverflowError

问题：简单代码记录 :

for (day <- days){

　　rdd = rdd.union(sc.textFile(/path/to/day) .... )

}

大概场景就是我想把数量比较多的文件合并成一个大rdd,从而导致了栈溢出；

解决：很明显是方法递归调用太多，我之后改成了几个小任务进行了合并；这里union也会造成最终rdd分区数过多

2.java.io.FileNotFoundException: /tmp/spark-90507c1d-e98 ..... temp_shuffle_98deadd9-f7c3-4a12(No such file or directory) 类似这种 

报错：Exception in thread "main" org.apache.spark.SparkException: Job aborted due to stage failure: Task 0 in stage 76.0 failed 4 times, most recent failure: Lost task 0.3 in stage 76.0 (TID 341, 10.5.0.90): java.io.FileNotFoundException: /tmp/spark-90507c1d-e983-422d-9e01-74ff0a5a2806/executor-360151d5-6b83-4e3e-a0c6-6ddc955cb16c/blockmgr-bca2bde9-212f-4219-af8b-ef0415d60bfa/26/temp_shuffle_98deadd9-f7c3-4a12-9a30-7749f097b5c8 (No such file or directory)

场景：大概代码和上面差不多：

for (day <- days){

　　rdd = rdd.union(sc.textFile(/path/to/day) .... )

}

rdd.map( ... )

解决：简单的map都会报错，怀疑是临时文件过多；查看一下rdd.partitions.length 果然有4k多个；基本思路就是减少分区数

可以在union的时候就进行重分区：

for (day <- days){

　　rdd = rdd.union(sc.textFile(/path/to/day,numPartitions) .... )

　　rdd = rdd.coalesce(numPartitions)

} //这里因为默认哈希分区，并且分区数相同；所有最终union的rdd的分区数不会增多,贴一下源码以防说错

  /** Build the union of a list of RDDs. */
  def union[T: ClassTag](rdds: Seq[RDD[T]]): RDD[T] = withScope {
    val partitioners = rdds.flatMap(_.partitioner).toSet
    if (rdds.forall(_.partitioner.isDefined) && partitioners.size == 1) {
      /*这里如果rdd的分区函数都相同则会构建一个PartitionerAwareUnionRDD：m RDDs with p partitions each
 * will be unified to a single RDD with p partitions*/
      new PartitionerAwareUnionRDD(this, rdds)
    } else {
      new UnionRDD(this, rdds)
    }
  }

或者最后在重分区

for (day <- days){

　　rdd = rdd.union(sc.textFile(/path/to/day) .... )

} 

rdd.repartition(numPartitions)

3.java.lang.NoClassDefFoundError: Could not initialize class com.tzg.scala.play.UserPlayStatsByUuid$

at com.tzg.scala.play.UserPlayStatsByUuid$$anonfun$main$2.apply(UserPlayStatsByUuid.scala:42)
at com.tzg.scala.play.UserPlayStatsByUuid$$anonfun$main$2.apply(UserPlayStatsByUuid.scala:40)

场景：用scala 写的一个类，把所有的常量都放到了类的成员变量声明部分，结果在加载这个类的成员变量时报错

反编译成java代码

public final class implements Serializable {

  public static final  MODULE$;
  private final int USER_OPERATION_OPERATION_TYPE;
  
  public int USER_OPERATION_OPERATION_TYPE() { return this.USER_OPERATION_OPERATION_TYPE; } 

  static
  {
    new ();
  }

　private Object readResolve(){return MODULE$; }

  private () {MODULE$ = this; this.USER_OPERATION_OPERATION_TYPE = 4;}

}

报错部分类字节码：

解决：在加载类的一个成员变量失败，导致抛出NoClassDefFoundError：Could not initialize class，把这些常量移出类的声明体，那么在初始化时肯定不会加载失败了

　　

4.ContextCleaner Time Out

17/01/04 03:32:49 [ERROR] [org.apache.spark.ContextCleaner:96] - Error cleaning broadcast 414
akka.pattern.AskTimeoutException: Timed out

解决:spark-submit增加了两个参数：

--conf spark.cleaner.referenceTracking.blocking=true
--conf spark.cleaner.referenceTracking.blocking.shuffle=true

 参考自spark-issue:SPARK-3139

5. java.lang.NoSuchMethodError: scala.Predef$.ArrowAssoc(Ljava/lang/Object;)

解决：scala环境和spark环境不匹配，spark1.x 对应scala10 ; spark2.x 对应scala11

6.join操作：

不管是spark还是pandas,都不会对两个join的表进行去重，所以如果要join的关联键是重复的，结果肯定会让人意想不到，所以谨记join时保证关联键是不重复的

　　rdd1 = sc.makeRDD(List('A','A','B'))

　　val pairs1 = rdd1.map(k => (k,1))

　　 val rdd2 = sc.makeRDD(List('A','B','B'))

　　val pairs2 = rdd2.map(k => (k,1))

　　pairs1.join(pairs2).collect() // Array[(Char, (Int, Int))] = Array((B,(1,1)), (B,(1,1)), (A,(1,1)), (A,(1,1)))

7.spark streaming Could not compute split, block input-0-1449191870000 not found

15/12/04 15:27:27 WARN [task-result-getter-0] TaskSetManager: Lost task 0.0 in stage 3.0 (TID 56, 192.168.0.2): java.lang.Exception: Could not compute split, block input-0-1449191870000 not found
    at org.apache.spark.rdd.BlockRDD.compute(BlockRDD.scala:51)
    at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:277)
    at org.apache.spark.rdd.RDD.iterator(RDD.scala:244)
    at org.apache.spark.rdd.MapPartitionsRDD.compute(MapPartitionsRDD.scala:35)
    at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:277)
    at org.apache.spark.rdd.RDD.iterator(RDD.scala:244)
    at org.apache.spark.rdd.MapPartitionsRDD.compute(MapPartitionsRDD.scala:35)
    at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:277)
    at org.apache.spark.rdd.RDD.iterator(RDD.scala:244)
    at org.apache.spark.scheduler.ShuffleMapTask.runTask(ShuffleMapTask.scala:70)
    at org.apache.spark.scheduler.ShuffleMapTask.runTask(ShuffleMapTask.scala:41)
    at org.apache.spark.scheduler.Task.run(Task.scala:70)
    at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:213)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)

解决：加大executor内存

8.JSON.parseFull(jsonArrayStr)抛出异常：

exception For input string: "1496713640091"
java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
java.lang.Integer.parseInt(Integer.java:495)
java.lang.Integer.parseInt(Integer.java:527)
scala.collection.immutable.StringLike$class.toInt(StringLike.scala:229)
scala.collection.immutable.StringOps.toInt(StringOps.scala:31)
kafka.utils.Json$$anonfun$1.apply(Json.scala:27)
kafka.utils.Json$$anonfun$1.apply(Json.scala:27)
scala.util.parsing.json.Parser$$anonfun$number$1.applyOrElse(Parser.scala:140)
scala.util.parsing.json.Parser$$anonfun$number$1.applyOrElse(Parser.scala:140)

问题很明显就是数值太大了，然后就各种找源码

scala-doc:http://www.scala-lang.org/api/2.10.5/index.html#scala.util.parsing.json.JSON$
scala-source:https://github.com/scala/scala/blob/v2.10.5/src/library/scala/util/parsing/json/JSON.scala#L1
　　https://github.com/scala/scala/blob/2.10.x/src/library/scala/util/parsing/combinator/Parsers.scala

kafka-source:

 　　https://github.com/apache/kafka/blob/trunk/core/src/main/scala/kafka/utils/Json.scala

截取重要代码如下：

可以看到kafka.util.Json的parseFull类会调用scala.util.parsing.json.JSON.parseFull方法，而这个JSON实例有个属性gobalNumberParser来指定数字型的字符串默认转成Int,这里就是问题所在，当数字过大的时候就会报错NumberFormatException

解决方法：

　修改默认转换函数：

val myConversionFunc = {input : String => input.toLong} //源码中是toInt,uid之类的会报错
JSON.globalNumberParser = myConversionFunc

9.最近学习google tensorflow下的wide and deep leanrning的教程，原教程是全部数据fit进去的，我的赛题数据太大，所以直接报错OOM,然后就开始找各种解决办法，如下是谷歌的官方回复,先贴在这里：

Wide_n_deep : question on input_fn(df) - Google Groups

然后我的需求就是将pandas对象直接转成tensor,然后做一个分批次的生成器，对应的核心代码剪切到这里：

def input_fn():
    """
    假定数据源是一个5行，	分隔的，类型全都是float的tsv文件;前4列是特征，后1列是目标变量 
    """
    parse_fn = lambda example: tf.decode_csv(records=example,
                                             record_defaults=[[0.0], [0.0], [0.0], [0.0], [0.0]],
                                             field_delim='	')

    inputs = tf.contrib.learn.read_batch_examples(file_pattern=file_paths,
                                                  batch_size=256,
                                                  reader=tf.TextLineReader,
                                                  randomize_input=True,
                                                  num_epochs=1,
                                                  queue_capacity=10000,
                                                  num_threads=1,
                                                  parse_fn=parse_fn,
                                                  seed = None)

    feats = {}

    for i, header in enumerate(["feature1", "feature2", "feature3", "feature4"]):
        feats[header] = inputs[:, i]
    targets = inputs[:, 4]

    return feats, targets

初学TF，顺便贴下相关函数的函数API:

tf.decode_csv方法

tf.contrib.learn.read_batch_examples

10.Unsupported major.minor version 52.0

Exception in thread "main" java.lang.UnsupportedClassVersionError: com/sensorsdata/analytics/tools/hdfsimporter/HdfsImporter : Unsupported major.minor version 52.0
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:800)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)
at java.net.URLClassLoader.access$100(URLClassLoader.java:71)
at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:270)
at org.apache.hadoop.util.RunJar.run(RunJar.java:214)
at org.apache.hadoop.util.RunJar.main(RunJar.java:136)

52是java 8的版本，需要升级原来的jdk,或者重新编译原来的类

11.java.sql.SQLException: Unable to open a test connection to the given database. JDBC url = jdbc:mysql://127.0.0.1/hive?createDatabaseIfNotExist=true

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
        at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
        at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
        at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
        at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1121)
        at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:357)
        at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2482)
        at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2519)
        at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2304)
        at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:834)
        at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
        at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
        at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
        at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
        at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:416)
        at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:346)
        at java.sql.DriverManager.getConnection(DriverManager.java:571)
        at java.sql.DriverManager.getConnection(DriverManager.java:187)
        at com.jolbox.bonecp.BoneCP.obtainRawInternalConnection(BoneCP.java:361)
        at com.jolbox.bonecp.BoneCP.<init>(BoneCP.java:416)
        at com.jolbox.bonecp.BoneCPDataSource.getConnection(BoneCPDataSource.java:120)
        at org.datanucleus.store.rdbms.ConnectionFactoryImpl$ManagedConnectionImpl.getConnection(ConnectionFactoryImpl.java:501)
        at org.datanucleus.store.rdbms.RDBMSStoreManager.<init>(RDBMSStoreManager.java:298)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
        at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
        at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
        at org.datanucleus.plugin.NonManagedPluginRegistry.createExecutableExtension(NonManagedPluginRegistry.java:631)
        at org.datanucleus.plugin.PluginManager.createExecutableExtension(PluginManager.java:301)
        at org.datanucleus.NucleusContext.createStoreManagerForProperties(NucleusContext.java:1187)
        at org.datanucleus.NucleusContext.initialise(NucleusContext.java:356)
        at org.datanucleus.api.jdo.JDOPersistenceManagerFactory.freezeConfiguration(JDOPersistenceManagerFactory.java:775)
        at org.datanucleus.api.jdo.JDOPersistenceManagerFactory.createPersistenceManagerFactory(JDOPersistenceManagerFactory.java:333)
        at org.datanucleus.api.jdo.JDOPersistenceManagerFactory.getPersistenceManagerFactory(JDOPersistenceManagerFactory.java:202)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:606)
        at javax.jdo.JDOHelper$16.run(JDOHelper.java:1965)
        at java.security.AccessController.doPrivileged(Native Method)
        at javax.jdo.JDOHelper.invoke(JDOHelper.java:1960)
        at javax.jdo.JDOHelper.invokeGetPersistenceManagerFactoryOnImplementation(JDOHelper.java:1166)
        at javax.jdo.JDOHelper.getPersistenceManagerFactory(JDOHelper.java:808)
        at javax.jdo.JDOHelper.getPersistenceManagerFactory(JDOHelper.java:701)
        at org.apache.hadoop.hive.metastore.ObjectStore.getPMF(ObjectStore.java:365)
        at org.apache.hadoop.hive.metastore.ObjectStore.getPersistenceManager(ObjectStore.java:394)
        at org.apache.hadoop.hive.metastore.ObjectStore.initialize(ObjectStore.java:291)
        at org.apache.hadoop.hive.metastore.ObjectStore.setConf(ObjectStore.java:258)
        at org.apache.hadoop.util.ReflectionUtils.setConf(ReflectionUtils.java:73)
        at org.apache.hadoop.util.ReflectionUtils.newInstance(ReflectionUtils.java:133)
        at org.apache.hadoop.hive.metastore.RawStoreProxy.<init>(RawStoreProxy.java:57)
        at org.apache.hadoop.hive.metastore.RawStoreProxy.getProxy(RawStoreProxy.java:66)
        at org.apache.hadoop.hive.metastore.HiveMetaStore$HMSHandler.newRawStore(HiveMetaStore.java:593)
        at org.apache.hadoop.hive.metastore.HiveMetaStore$HMSHandler.getMS(HiveMetaStore.java:571)
        at org.apache.hadoop.hive.metastore.HiveMetaStore$HMSHandler.createDefaultDB(HiveMetaStore.java:620)
        at org.apache.hadoop.hive.metastore.HiveMetaStore$HMSHandler.init(HiveMetaStore.java:461)
        at org.apache.hadoop.hive.metastore.RetryingHMSHandler.<init>(RetryingHMSHandler.java:66)
        at org.apache.hadoop.hive.metastore.RetryingHMSHandler.getProxy(RetryingHMSHandler.java:72)
        at org.apache.hadoop.hive.metastore.HiveMetaStore.newRetryingHMSHandler(HiveMetaStore.java:5762)
        at org.apache.hadoop.hive.metastore.HiveMetaStoreClient.<init>(HiveMetaStoreClient.java:199)
        at org.apache.hadoop.hive.ql.metadata.SessionHiveMetaStoreClient.<init>(SessionHiveMetaStoreClient.java:74)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
        at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
        at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
        at org.apache.hadoop.hive.metastore.MetaStoreUtils.newInstance(MetaStoreUtils.java:1521)
        at org.apache.hadoop.hive.metastore.RetryingMetaStoreClient.<init>(RetryingMetaStoreClient.java:86)
        at org.apache.hadoop.hive.metastore.RetryingMetaStoreClient.getProxy(RetryingMetaStoreClient.java:132)
        at org.apache.hadoop.hive.metastore.RetryingMetaStoreClient.getProxy(RetryingMetaStoreClient.java:104)
        at org.apache.hadoop.hive.ql.metadata.Hive.createMetaStoreClient(Hive.java:3005)
        at org.apache.hadoop.hive.ql.metadata.Hive.getMSC(Hive.java:3024)
        at org.apache.hadoop.hive.ql.session.SessionState.start(SessionState.java:503)
        at org.apache.spark.sql.hive.client.ClientWrapper.<init>(ClientWrapper.scala:204)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
        at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
        at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
        at org.apache.spark.sql.hive.client.IsolatedClientLoader.createClient(IsolatedClientLoader.scala:249)
        at org.apache.spark.sql.hive.HiveContext.metadataHive$lzycompute(HiveContext.scala:327)
        at org.apache.spark.sql.hive.HiveContext.metadataHive(HiveContext.scala:237)
        at org.apache.spark.sql.hive.HiveContext.setConf(HiveContext.scala:441)
        at org.apache.spark.sql.hive.HiveContext.defaultOverrides(HiveContext.scala:226)
        at org.apache.spark.sql.hive.HiveContext.<init>(HiveContext.scala:229)
        at org.apache.spark.sql.hive.HiveContext.<init>(HiveContext.scala:101)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
        at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
        at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
        at py4j.reflection.MethodInvoker.invoke(MethodInvoker.java:234)
        at py4j.reflection.ReflectionEngine.invoke(ReflectionEngine.java:381)
        at py4j.Gateway.invoke(Gateway.java:214)
        at py4j.commands.ConstructorCommand.invokeConstructor(ConstructorCommand.java:79)
        at py4j.commands.ConstructorCommand.execute(ConstructorCommand.java:68)
        at py4j.GatewayConnection.run(GatewayConnection.java:209)
        at java.lang.Thread.run(Thread.java:745)
Caused by: java.net.ConnectException: Connection refused
        at java.net.PlainSocketImpl.socketConnect(Native Method)
        at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:339)
        at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:200)
        at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:182)
        at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
        at java.net.Socket.connect(Socket.java:579)
        at java.net.Socket.connect(Socket.java:528)
        at java.net.Socket.<init>(Socket.java:425)
        at java.net.Socket.<init>(Socket.java:241)
        at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:259)
        at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:307)
        ... 91 more

解决：修改$SPARK_HOME/conf/hive-site.xml的javax.jdo.option.ConnectionURL值为正确的mysql连接串

 keras训练多文本分类的时候，总是碰到loss为nan的情况，如下图：

那么我试验中两个debug的地方就是修改激活函数和最后一个全连接层的神经元个数：

激活函数是softmax,最后一层神经元是类别个数的两倍

12.Mongo Hadoop Connector使用过程中，hive查询where不可以使用等号"=" 

从上图可以明显看出，“=”并不能获得期望的结果，可以通过使用“in”或者“like”来获取期望结果。同时，“==”并不会报错，而且效果与“=”一致，都是错误的。

13.Caused by: java.io.FileNotFoundException: File does not exist: hdfs://nameservice/user/hive/warehouse/prod.db/my_table/000000_0_copy_2

场景：hadoop多用户使用，一个程序往hive数据库写，另一个程序去查；就会出现数据不存在的问题