### What changes were proposed in this pull request?
This patch proposes:
1. Fix OOM at WideSchemaBenchmark: make `ValidateExternalType.errMsg` lazy variable, i.e. not to initiate it in the constructor
2. Truncate `errMsg`: Replacing `catalogString` with `simpleString` which is truncated
3. Optimizing `override def catalogString` in `StructType`: Make `catalogString` more efficient in string generation by using `StringConcat`
### Why are the changes needed?
In the JIRA, it is found that WideSchemaBenchmark fails with OOM, like:
```
[error] Exception in thread "main" org.apache.spark.sql.catalyst.errors.package$TreeNodeException: makeCopy, tree: validateexternaltype(getexternalrowfield(input[0, org.apac
he.spark.sql.Row, true], 0, a), StructField(b,StructType(StructField(c,StructType(StructField(value_1,LongType,true), StructField(value_10,LongType,true), StructField(value_
100,LongType,true), StructField(value_1000,LongType,true), StructField(value_1001,LongType,true), StructField(value_1002,LongType,true), StructField(value_1003,LongType,true
), StructField(value_1004,LongType,true), StructField(value_1005,LongType,true), StructField(value_1006,LongType,true), StructField(value_1007,LongType,true), StructField(va
lue_1008,LongType,true), StructField(value_1009,LongType,true), StructField(value_101,LongType,true), StructField(value_1010,LongType,true), StructField(value_1011,LongType,
...
ue), StructField(value_99,LongType,true), StructField(value_990,LongType,true), StructField(value_991,LongType,true), StructField(value_992,LongType,true), StructField(value
_993,LongType,true), StructField(value_994,LongType,true), StructField(value_995,LongType,true), StructField(value_996,LongType,true), StructField(value_997,LongType,true),
StructField(value_998,LongType,true), StructField(value_999,LongType,true)),true))
[error] at org.apache.spark.sql.catalyst.errors.package$.attachTree(package.scala:56)
[error] at org.apache.spark.sql.catalyst.trees.TreeNode.makeCopy(TreeNode.scala:435)
[error] at org.apache.spark.sql.catalyst.trees.TreeNode.mapChildren(TreeNode.scala:408)
[error] at org.apache.spark.sql.catalyst.trees.TreeNode.mapChildren(TreeNode.scala:327)
[error] at org.apache.spark.sql.catalyst.trees.TreeNode.transformUp(TreeNode.scala:307)
....
[error] at org.apache.spark.sql.catalyst.trees.TreeNode.$anonfun$mapChildren$1(TreeNode.scala:404)
[error] at org.apache.spark.sql.catalyst.trees.TreeNode.mapProductIterator(TreeNode.scala:214)
[error] at org.apache.spark.sql.catalyst.trees.TreeNode.mapChildren(TreeNode.scala:374)
[error] at org.apache.spark.sql.catalyst.trees.TreeNode.mapChildren(TreeNode.scala:327)
[error] at org.apache.spark.sql.catalyst.trees.TreeNode.transformUp(TreeNode.scala:307)
[error] at org.apache.spark.sql.catalyst.trees.TreeNode.$anonfun$transformUp$1(TreeNode.scala:307)
[error] at org.apache.spark.sql.catalyst.trees.TreeNode.$anonfun$mapChildren$1(TreeNode.scala:376)
[error] at org.apache.spark.sql.catalyst.trees.TreeNode.mapProductIterator(TreeNode.scala:214)
[error] at org.apache.spark.sql.catalyst.trees.TreeNode.mapChildren(TreeNode.scala:374)
[error] at org.apache.spark.sql.catalyst.trees.TreeNode.mapChildren(TreeNode.scala:327)
[error] at org.apache.spark.sql.catalyst.trees.TreeNode.transformUp(TreeNode.scala:307)
[error] at org.apache.spark.sql.catalyst.encoders.ExpressionEncoder.<init>(ExpressionEncoder.scala:198)
[error] at org.apache.spark.sql.catalyst.encoders.RowEncoder$.apply(RowEncoder.scala:71)
[error] at org.apache.spark.sql.Dataset$.ofRows(Dataset.scala:88)
[error] at org.apache.spark.sql.SparkSession.internalCreateDataFrame(SparkSession.scala:554)
[error] at org.apache.spark.sql.DataFrameReader.json(DataFrameReader.scala:476)
[error] at org.apache.spark.sql.execution.benchmark.WideSchemaBenchmark$.$anonfun$wideShallowlyNestedStructFieldReadAndWrite$1(WideSchemaBenchmark.scala:126)
...
[error] Caused by: java.lang.OutOfMemoryError: GC overhead limit exceeded
[error] at java.util.Arrays.copyOf(Arrays.java:3332)
[error] at java.lang.AbstractStringBuilder.ensureCapacityInternal(AbstractStringBuilder.java:124)
[error] at java.lang.AbstractStringBuilder.append(AbstractStringBuilder.java:448)
[error] at java.lang.StringBuilder.append(StringBuilder.java:136)
[error] at scala.collection.mutable.StringBuilder.append(StringBuilder.scala:213)
[error] at scala.collection.TraversableOnce.$anonfun$addString$1(TraversableOnce.scala:368)
[error] at scala.collection.TraversableOnce$$Lambda$67/667447085.apply(Unknown Source)
[error] at scala.collection.IndexedSeqOptimized.foreach(IndexedSeqOptimized.scala:36)
[error] at scala.collection.IndexedSeqOptimized.foreach$(IndexedSeqOptimized.scala:33)
[error] at scala.collection.mutable.ArrayOps$ofRef.foreach(ArrayOps.scala:198)
[error] at scala.collection.TraversableOnce.addString(TraversableOnce.scala:362)
[error] at scala.collection.TraversableOnce.addString$(TraversableOnce.scala:358)
[error] at scala.collection.mutable.ArrayOps$ofRef.addString(ArrayOps.scala:198)
[error] at scala.collection.TraversableOnce.mkString(TraversableOnce.scala:328)
[error] at scala.collection.TraversableOnce.mkString$(TraversableOnce.scala:327)
[error] at scala.collection.mutable.ArrayOps$ofRef.mkString(ArrayOps.scala:198)
[error] at scala.collection.TraversableOnce.mkString(TraversableOnce.scala:330)
[error] at scala.collection.TraversableOnce.mkString$(TraversableOnce.scala:330)
[error] at scala.collection.mutable.ArrayOps$ofRef.mkString(ArrayOps.scala:198)
[error] at org.apache.spark.sql.types.StructType.catalogString(StructType.scala:411)
[error] at org.apache.spark.sql.catalyst.expressions.objects.ValidateExternalType.<init>(objects.scala:1695)
[error] at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
[error] at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
[error] at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
[error] at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
[error] at org.apache.spark.sql.catalyst.trees.TreeNode.$anonfun$makeCopy$7(TreeNode.scala:468)
[error] at org.apache.spark.sql.catalyst.trees.TreeNode$$Lambda$934/387827651.apply(Unknown Source)
[error] at org.apache.spark.sql.catalyst.trees.CurrentOrigin$.withOrigin(TreeNode.scala:72)
[error] at org.apache.spark.sql.catalyst.trees.TreeNode.$anonfun$makeCopy$1(TreeNode.scala:467)
[error] at org.apache.spark.sql.catalyst.trees.TreeNode$$Lambda$929/449240381.apply(Unknown Source)
[error] at org.apache.spark.sql.catalyst.errors.package$.attachTree(package.scala:52)
[error] at org.apache.spark.sql.catalyst.trees.TreeNode.makeCopy(TreeNode.scala:435)
```
It is after cb5ea201df commit which refactors `ExpressionEncoder`.
The stacktrace shows it fails at `transformUp` on `objSerializer` in `ExpressionEncoder`. In particular, it fails at initializing `ValidateExternalType.errMsg`, that interpolates `catalogString` of given `expected` data type in a string. In WideSchemaBenchmark we have very deeply nested data type. When we transform on the serializer which contains `ValidateExternalType`, we create redundant big string `errMsg`. Because we just in transforming it and don't use it yet, it is useless and waste a lot of memory.
After make `ValidateExternalType.errMsg` as lazy variable, WideSchemaBenchmark works.
### Does this PR introduce any user-facing change?
No
### How was this patch tested?
Manual test with WideSchemaBenchmark.
Closes#27117 from viirya/SPARK-30429.
Lead-authored-by: Liang-Chi Hsieh <liangchi@uber.com>
Co-authored-by: Liang-Chi Hsieh <viirya@gmail.com>
Signed-off-by: Dongjoon Hyun <dhyun@apple.com>
1160457eed