### What changes were proposed in this pull request?
After my investigation, `SQLQueryTestSuite` spent a lot of time compiling the generated java code.
Take `group-by.sql` as an example.
At first, I added some debug log into `SQLQueryTestSuite`.
Please reference 92b6af740c/sql/core/src/test/scala/org/apache/spark/sql/SQLQueryTestSuite.scala (L402)
The execution command is as follows:
`build/sbt "~sql/test-only *SQLQueryTestSuite -- -z group-by.sql"`
The output show below:
```
00:56:06.192 WARN org.apache.spark.sql.SQLQueryTestSuite: group-by.sql using configs: spark.sql.codegen.wholeStage=true. run time: 20604
00:56:13.719 WARN org.apache.spark.sql.SQLQueryTestSuite: group-by.sql using configs: spark.sql.codegen.wholeStage=false,spark.sql.codegen.factoryMode=CODEGEN_ONLY. run time: 7526
00:56:18.786 WARN org.apache.spark.sql.SQLQueryTestSuite: group-by.sql using configs: spark.sql.codegen.wholeStage=false,spark.sql.codegen.factoryMode=NO_CODEGEN. run time: 5066
```
According to the log, we know.
Config | Run time(ms)
-- | --
spark.sql.codegen.wholeStage=true | 20604
spark.sql.codegen.wholeStage=false,spark.sql.codegen.factoryMode=CODEGEN_ONLY | 7526
spark.sql.codegen.wholeStage=false,spark.sql.codegen.factoryMode=NO_CODEGEN | 5066
We should display the total compile time for generated java code.
This PR will add the following to `SQLQueryTestSuite`'s output.
```
=== Metrics of Whole Codegen ===
Total compile time: 80.564516529 seconds
```
Note: At first, I wanted to use `CodegenMetrics.METRIC_COMPILATION_TIME` to do this. After many experiments, I found that `CodegenMetrics.METRIC_COMPILATION_TIME` is only effective for a single test case, and cannot play a role in the whole life cycle of `SQLQueryTestSuite`.
I checked the type of ` CodegenMetrics.METRIC_COMPILATION_TIME` is `Histogram` and the latter preserves 1028 elements.` Histogram` is a metric which calculates the distribution of a value.
### Why are the changes needed?
Display the total compile time for generated java code.
### Does this PR introduce any user-facing change?
'No'.
### How was this patch tested?
Jenkins test.
Closes#28081 from beliefer/output-codegen-compile-time.
Lead-authored-by: beliefer <beliefer@163.com>
Co-authored-by: gengjiaan <gengjiaan@360.cn>
Signed-off-by: Wenchen Fan <wenchen@databricks.com>
a9260d0349