Cannot load a saved Spark model in pyspark: “java.lang.NoSuchMethodException”

问题

When I run the following Python program

from pyspark.ml.classification import LinearSVC
from pyspark.sql import SparkSession

spark = SparkSession.builder.appName("Sparkmodel").getOrCreate()
data = spark.read.format("libsvm").load("/usr/local/spark/data/mllib/sample_libsvm_data.txt")
model = LinearSVC().fit(data)
model.save("mymodel")
LinearSVC.load("mymodel")

the load fails with a "java.lang.NoSuchMethodException".

/anaconda3/envs/scratch/bin/python /Users/billmcn/src/toy/sparkmodel/sparkmodel/little.py
Using Spark's default log4j profile: org/apache/spark/log4j-defaults.properties
Setting default log level to "WARN".
To adjust logging level use sc.setLogLevel(newLevel). For SparkR, use setLogLevel(newLevel).
17/11/12 13:23:05 WARN NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
17/11/12 13:23:06 WARN Utils: Service 'SparkUI' could not bind on port 4040. Attempting port 4041.
17/11/12 13:23:06 WARN Utils: Service 'SparkUI' could not bind on port 4041. Attempting port 4042.
17/11/12 13:23:17 WARN BLAS: Failed to load implementation from: com.github.fommil.netlib.NativeSystemBLAS
17/11/12 13:23:17 WARN BLAS: Failed to load implementation from: com.github.fommil.netlib.NativeRefBLAS
Traceback (most recent call last):
  File "/Users/billmcn/src/toy/sparkmodel/sparkmodel/little.py", line 9, in <module>
    LinearSVC.load("mymodel")
  File "/anaconda3/envs/scratch/lib/python3.6/site-packages/pyspark/ml/util.py", line 257, in load
    return cls.read().load(path)
  File "/anaconda3/envs/scratch/lib/python3.6/site-packages/pyspark/ml/util.py", line 197, in load
    java_obj = self._jread.load(path)
  File "/anaconda3/envs/scratch/lib/python3.6/site-packages/py4j/java_gateway.py", line 1160, in __call__
    answer, self.gateway_client, self.target_id, self.name)
  File "/anaconda3/envs/scratch/lib/python3.6/site-packages/pyspark/sql/utils.py", line 63, in deco
    return f(*a, **kw)
  File "/anaconda3/envs/scratch/lib/python3.6/site-packages/py4j/protocol.py", line 320, in get_return_value
    format(target_id, ".", name), value)
py4j.protocol.Py4JJavaError: An error occurred while calling o64.load.
: java.lang.NoSuchMethodException: org.apache.spark.ml.classification.LinearSVCModel.<init>(java.lang.String)
    at java.lang.Class.getConstructor0(Class.java:3082)
    at java.lang.Class.getConstructor(Class.java:1825)
    at org.apache.spark.ml.util.DefaultParamsReader.load(ReadWrite.scala:328)
    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:280)
    at py4j.commands.AbstractCommand.invokeMethod(AbstractCommand.java:132)
    at py4j.commands.CallCommand.execute(CallCommand.java:79)
    at py4j.GatewayConnection.run(GatewayConnection.java:214)
    at java.lang.Thread.run(Thread.java:748)


Process finished with exit code 1

The "mymodel" directory is created and its contents appear to be valid.

I am running Spark 2.2.0 and pyspark 2.2.0. I have the following mllib jars in my installation.

> ll /usr/local/spark.versions/spark-2.2.0-bin-hadoop2.7/jars/spark-mllib*
-rw-r--r--@ 1 billmcn  admin  6501535 Jun 30 18:09 /usr/local/spark.versions/spark-2.2.0-bin-hadoop2.7/jars/spark-mllib_2.11-2.2.0.jar
-rw-r--r--@ 1 billmcn  admin   182887 Jun 30 18:09 /usr/local/spark.versions/spark-2.2.0-bin-hadoop2.7/jars/spark-mllib-local_2.11-2.2.0.jar

And the latter contains the class I want.

jar tf /usr/local/spark.versions/spark-2.2.0-bin-hadoop2.7/jars/spark-mllib_2.11-2.2.0.jar | grep LinearSVCModel
org/apache/spark/ml/classification/LinearSVCModel$LinearSVCWriter$Data.class
org/apache/spark/ml/classification/LinearSVCModel$.class
org/apache/spark/ml/classification/LinearSVCModel$LinearSVCWriter.class
org/apache/spark/ml/classification/LinearSVCModel$LinearSVCReader.class
org/apache/spark/ml/classification/LinearSVCModel$$anonfun$11.class
org/apache/spark/ml/classification/LinearSVCModel$LinearSVCWriter$$typecreator1$1.class
org/apache/spark/ml/classification/LinearSVCModel$LinearSVCWriter$Data$.class
org/apache/spark/ml/classification/LinearSVCModel.class

The same problem happens on two different machines.

What am I doing wrong?

回答1:

This looks like a version mismatch. The most likely scenario is:

Your Python (PySpark) installation uses Spark 2.2
While JVM jars have been compiled with earlier Spark version, which didn't include LinearSVCModel.

回答2:

I was using the wrong class to load the module. The following works

model = LinearSVCModel.load(model_path)

来源：https://stackoverflow.com/questions/47253131/cannot-load-a-saved-spark-model-in-pyspark-java-lang-nosuchmethodexception

标签

apache-spark

pyspark

deserialization