使用 mongo-spark-connector 连接到 mongodb 时出错

Question

我是 spark/mongodb 的新手，我正在尝试使用 mongo-spark-connector 按照说明 here 从 pyspark 连接到 mongo。我用命令

启动 pyspark

`pyspark \
--conf 'spark.mongodb.input.uri=mongodb://127.0.0.1/mydb.mytable?readPreference=primaryPreferred' \ 
--conf 'spark.mongodb.output.uri=mongodb://127.0.0.1/mydb.mytable' \ 
--packages org.mongodb.spark:mongo-spark-connector_2.11:2.4.1`

它在启动时给出以下信息：

`SLF4J: Class path contains multiple SLF4J bindings.
 SLF4J: Found binding in [jar:file:/usr/local/spark-2.4.4-bin-hadoop2.7/jars/slf4j log4j12-1.7.16.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/usr/local/hadoop-3.2.1/share/hadoop/common/lib/slf4j-log4j12-1.7.25.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
SLF4J: Actual binding is of type [org.slf4j.impl.Log4jLoggerFactory]
Ivy Default Cache set to: /home/mmr/.ivy2/cache
The jars for the packages stored in: /home/user_name/.ivy2/jars
:: loading settings :: url = jar:file:/usr/local/spark-2.4.4-bin-hadoop2.7/jars/ivy-2.4.0.jar!/org/apache/ivy/core/settings/ivysettings.xml
org.mongodb.spark#mongo-spark-connector_2.11 added as a dependency
:: resolving dependencies :: org.apache.spark#spark-submit-parent-18ec2360-9f44-414c-a1de-11f629819aec;1.0
    confs: [default]
    found org.mongodb.spark#mongo-spark-connector_2.11;2.4.1 in central
    found org.mongodb#mongo-java-driver;3.10.2 in central
    [3.10.2] org.mongodb#mongo-java-driver;[3.10,3.11)
:: resolution report :: resolve 1360ms :: artifacts dl 3ms
    :: modules in use:
    org.mongodb#mongo-java-driver;3.10.2 from central in [default]
    org.mongodb.spark#mongo-spark-connector_2.11;2.4.1 from central in [default]
    ---------------------------------------------------------------------
    |                  |            modules            ||   artifacts   |
    |       conf       | number| search|dwnlded|evicted|| number|dwnlded|
    ---------------------------------------------------------------------
    |      default     |   2   |   1   |   0   |   0   ||   2   |   0   |
    ---------------------------------------------------------------------
:: retrieving :: org.apache.spark#spark-submit-parent-18ec2360-9f44-414c-a1de-11f629819aec
    confs: [default]
    0 artifacts copied, 2 already retrieved (0kB/4ms)
20/01/24 00:21:29 WARN Utils: Your hostname, user_name-Machine resolves to a loopback address: 127.0.1.1; using 192.168.1.18 instead (on interface wlan0)
20/01/24 00:21:29 WARN Utils: Set SPARK_LOCAL_IP if you need to bind to another address
20/01/24 00:21:30 WARN NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
Setting default log level to "WARN".`

当我运行>>> df = spark.read.format("mongo").load() 时出现以下错误：

`Traceback (most recent call last):
 File "<stdin>", line 1, in <module>
 File "/usr/local/spark/python/pyspark/sql/readwriter.py", line 172, in load
 return self._df(self._jreader.load())
 File "/usr/local/spark/python/lib/py4j-0.10.7-src.zip/py4j/java_gateway.py", line 1257, in __call__
 File "/usr/local/spark/python/pyspark/sql/utils.py", line 63, in deco
 return f(*a, **kw)
 File "/usr/local/spark/python/lib/py4j-0.10.7-src.zip/py4j/protocol.py", line 328, in get_return_value
py4j.protocol.Py4JJavaError: An error occurred while calling o39.load.
: java.lang.NoSuchMethodError: com.mongodb.MongoClient.<init>(Lcom/mongodb/MongoClientURI;Lcom/mongodb/MongoDriverInformation;)V
    at com.mongodb.spark.connection.DefaultMongoClientFactory.create(DefaultMongoClientFactory.scala:49)
    at com.mongodb.spark.connection.MongoClientCache.acquire(MongoClientCache.scala:55)
    at com.mongodb.spark.MongoConnector.acquireClient(MongoConnector.scala:242)
    at com.mongodb.spark.MongoConnector.withMongoClientDo(MongoConnector.scala:155)
    at com.mongodb.spark.MongoConnector.withDatabaseDo(MongoConnector.scala:174)
    at com.mongodb.spark.MongoConnector.hasSampleAggregateOperator(MongoConnector.scala:237)
    at com.mongodb.spark.rdd.MongoRDD.hasSampleAggregateOperator$lzycompute(MongoRDD.scala:221)
    at com.mongodb.spark.rdd.MongoRDD.hasSampleAggregateOperator(MongoRDD.scala:221)
    at com.mongodb.spark.sql.MongoInferSchema$.apply(MongoInferSchema.scala:68)
    at com.mongodb.spark.sql.DefaultSource.constructRelation(DefaultSource.scala:97)
    at com.mongodb.spark.sql.DefaultSource.createRelation(DefaultSource.scala:50)
    at org.apache.spark.sql.execution.datasources.DataSource.resolveRelation(DataSource.scala:318)
    at org.apache.spark.sql.DataFrameReader.loadV1Source(DataFrameReader.scala:223)
    at org.apache.spark.sql.DataFrameReader.load(DataFrameReader.scala:211)
    at org.apache.spark.sql.DataFrameReader.load(DataFrameReader.scala:167)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at py4j.reflection.MethodInvoker.invoke(MethodInvoker.java:244)
    at py4j.reflection.ReflectionEngine.invoke(ReflectionEngine.java:357)
    at py4j.Gateway.invoke(Gateway.java:282)
    at py4j.commands.AbstractCommand.invokeMethod(AbstractCommand.java:132)
    at py4j.commands.CallCommand.execute(CallCommand.java:79)
    at py4j.GatewayConnection.run(GatewayConnection.java:238)
    at java.lang.Thread.run(Thread.java:748)`

规格：

操作系统：Ubuntu 18.04

java: openjdk 8

火花：2.4.4

mongo：4.2.2

斯卡拉：2.11.12

mongo java 驱动：3.12

我尝试使用 Orace java 8，并将 mongo 驱动程序切换到 3.10.2。

Answer 1

第一个错误是由于冲突的 slf4j 记录器依赖而发生的。 Spark mongo 连接器 jar 将 slf4j 列为依赖项。见maven package info。然而，这只是一个警告，spark 会选择第一个可用的。似乎这个 jar 在您的系统上安装了两次。一个来自 spark 包，一个来自 hadoop。 Mongo-connector 将此列为提供的依赖项，并且 spark 使用系统上的任何依赖项。

通常可以排除带有

的罐子

--exclude-packages 逗号分隔的 groupId:artifactId 列表，排除 while 解决 --packages 中提供的依赖项以避免 依赖冲突。

例如

--exclude-packages org.slf4j:slf4j-api

但是我认为这不是问题。

第二个错误告诉我们，这样的 MongoClient 构造方法不存在。 MongoClient 是 mongo spark 连接器的 java 包依赖。要么它根本没有正确加载。或者您以某种方式错误地传递了 conf 选项，最终调用 MongoClient 构造函数时没有正确的参数（不同的数量或错误的类型）。

我看到您在命令周围使用了不同的 qouting 和反引号。您还写了您已尝试安装 java mongo 驱动程序。您是否在类路径的某处放置了一个 jar。这不是必需的。 --packages 参数解析来自 maven 的依赖关系。 mongo-spark-connector 取决于 mongo-driver 并且应该为您解决它。请参阅 maven info 和 source。包含此依赖项（与提供的 slf4j 相比）

尝试将下面的确切命令粘贴到您的 shell 中。不要手动安装 mongo java 驱动。

pyspark \
--conf "spark.mongodb.input.uri=mongodb://127.0.0.1/mydb.mytable?readPreference=primaryPreferred" \
--conf "spark.mongodb.output.uri=mongodb://127.0.0.1/mydb.mytable" \
--packages org.mongodb.spark:mongo-spark-connector_2.11:2.4.1

当我运行这个命令时，~/.ivy2/cache 上自动安装了 2 个 jar

org.mongodb.spark_mongo-spark-connector_2.11-2.4.1.jar
org.mongodb_mongo-java-driver-3.10.2.jar

没有安装冲突的 slf4j。 jar 也不包含来自其他包的任何其他依赖代码。你可以用unzip -l <jar-file-name>.jar检查分类