## What changes were proposed in this pull request?
Calling `ImageSchema.readImages` multiple times as below in PySpark shell:
```python
from pyspark.ml.image import ImageSchema
data_path = 'data/mllib/images/kittens'
_ = ImageSchema.readImages(data_path, recursive=True, dropImageFailures=True).collect()
_ = ImageSchema.readImages(data_path, recursive=True, dropImageFailures=True).collect()
```
throws an error as below:
```
...
org.datanucleus.exceptions.NucleusDataStoreException: Unable to open a test connection to the given database. JDBC url = jdbc:derby:;databaseName=metastore_db;create=true, username = APP. Terminating connection pool (set lazyInit to true if you expect to start your database after your app). Original Exception: ------
java.sql.SQLException: Failed to start database 'metastore_db' with class loader org.apache.spark.sql.hive.client.IsolatedClientLoader$$anon$1742f639f, see the next exception for details.
...
at org.apache.derby.jdbc.AutoloadedDriver.connect(Unknown Source)
...
at org.apache.hadoop.hive.metastore.HiveMetaStore.newRetryingHMSHandler(HiveMetaStore.java:5762)
...
at org.apache.spark.sql.hive.client.HiveClientImpl.newState(HiveClientImpl.scala:180)
...
at org.apache.spark.sql.hive.HiveExternalCatalog$$anonfun$databaseExists$1.apply$mcZ$sp(HiveExternalCatalog.scala:195)
at org.apache.spark.sql.hive.HiveExternalCatalog$$anonfun$databaseExists$1.apply(HiveExternalCatalog.scala:195)
at org.apache.spark.sql.hive.HiveExternalCatalog$$anonfun$databaseExists$1.apply(HiveExternalCatalog.scala:195)
at org.apache.spark.sql.hive.HiveExternalCatalog.withClient(HiveExternalCatalog.scala:97)
at org.apache.spark.sql.hive.HiveExternalCatalog.databaseExists(HiveExternalCatalog.scala:194)
at org.apache.spark.sql.internal.SharedState.externalCatalog$lzycompute(SharedState.scala:100)
at org.apache.spark.sql.internal.SharedState.externalCatalog(SharedState.scala:88)
at org.apache.spark.sql.hive.HiveSessionStateBuilder.externalCatalog(HiveSessionStateBuilder.scala:39)
at org.apache.spark.sql.hive.HiveSessionStateBuilder.catalog$lzycompute(HiveSessionStateBuilder.scala:54)
at org.apache.spark.sql.hive.HiveSessionStateBuilder.catalog(HiveSessionStateBuilder.scala:52)
at org.apache.spark.sql.hive.HiveSessionStateBuilder$$anon$1.<init>(HiveSessionStateBuilder.scala:69)
at org.apache.spark.sql.hive.HiveSessionStateBuilder.analyzer(HiveSessionStateBuilder.scala:69)
at org.apache.spark.sql.internal.BaseSessionStateBuilder$$anonfun$build$2.apply(BaseSessionStateBuilder.scala:293)
at org.apache.spark.sql.internal.BaseSessionStateBuilder$$anonfun$build$2.apply(BaseSessionStateBuilder.scala:293)
at org.apache.spark.sql.internal.SessionState.analyzer$lzycompute(SessionState.scala:79)
at org.apache.spark.sql.internal.SessionState.analyzer(SessionState.scala:79)
at org.apache.spark.sql.execution.QueryExecution.analyzed$lzycompute(QueryExecution.scala:70)
at org.apache.spark.sql.execution.QueryExecution.analyzed(QueryExecution.scala:68)
at org.apache.spark.sql.execution.QueryExecution.assertAnalyzed(QueryExecution.scala:51)
at org.apache.spark.sql.Dataset$.ofRows(Dataset.scala:70)
at org.apache.spark.sql.SparkSession.internalCreateDataFrame(SparkSession.scala:574)
at org.apache.spark.sql.SparkSession.createDataFrame(SparkSession.scala:593)
at org.apache.spark.sql.SparkSession.createDataFrame(SparkSession.scala:348)
at org.apache.spark.sql.SparkSession.createDataFrame(SparkSession.scala:348)
at org.apache.spark.ml.image.ImageSchema$$anonfun$readImages$2$$anonfun$apply$1.apply(ImageSchema.scala:253)
...
Caused by: ERROR XJ040: Failed to start database 'metastore_db' with class loader org.apache.spark.sql.hive.client.IsolatedClientLoader$$anon$1742f639f, see the next exception for details.
at org.apache.derby.iapi.error.StandardException.newException(Unknown Source)
at org.apache.derby.impl.jdbc.SQLExceptionFactory.wrapArgsForTransportAcrossDRDA(Unknown Source)
... 121 more
Caused by: ERROR XSDB6: Another instance of Derby may have already booted the database /.../spark/metastore_db.
...
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/.../spark/python/pyspark/ml/image.py", line 190, in readImages
dropImageFailures, float(sampleRatio), seed)
File "/.../spark/python/lib/py4j-0.10.6-src.zip/py4j/java_gateway.py", line 1160, in __call__
File "/.../spark/python/pyspark/sql/utils.py", line 69, in deco
raise AnalysisException(s.split(': ', 1)[1], stackTrace)
pyspark.sql.utils.AnalysisException: u'java.lang.RuntimeException: java.lang.RuntimeException: Unable to instantiate org.apache.hadoop.hive.ql.metadata.SessionHiveMetaStoreClient;'
```
Seems we better stick to `SparkSession.builder.getOrCreate()` like:
51620e288b/python/pyspark/sql/streaming.py (L329)dc5d34d8dc/python/pyspark/sql/column.py (L541)33d43bf1b6/python/pyspark/sql/readwriter.py (L105)
## How was this patch tested?
This was tested as below in PySpark shell:
```python
from pyspark.ml.image import ImageSchema
data_path = 'data/mllib/images/kittens'
_ = ImageSchema.readImages(data_path, recursive=True, dropImageFailures=True).collect()
_ = ImageSchema.readImages(data_path, recursive=True, dropImageFailures=True).collect()
```
Author: hyukjinkwon <gurwls223@gmail.com>
Closes#19845 from HyukjinKwon/SPARK-22651.
aa4cf2b19e