fixup

backends-velox/src/main/scala/org/apache/gluten/backendsapi/velox/VeloxListenerApi.scala

@@ -34,12 +34,28 @@ import org.apache.spark.util.SparkDirectoryUtil
 
 import org.apache.commons.lang3.StringUtils
 
+import java.util.concurrent.atomic.AtomicBoolean
+
 class VeloxListenerApi extends ListenerApi with Logging {
   import VeloxListenerApi._
 
+  // TODO: Implement graceful shutdown and remove these flags.
+  //  As spark conf may change when active Spark session is recreated.
+  private val driverInitialized: AtomicBoolean = new AtomicBoolean(false)
+  private val executorInitialized: AtomicBoolean = new AtomicBoolean(false)
+
   override def onDriverStart(sc: SparkContext, pc: PluginContext): Unit = {
+    if (!driverInitialized.compareAndSet(false, true)) {
+      // Make sure we call the static initializers only once.
+      logInfo(
+        "Skip rerunning static initializers since they are already called." +
+          " It's probably because you are creating a new SparkSession.")
+      return
+    }
+
+    // Static initializers for driver.
     val conf = pc.conf()
-    // sql table cache serializer
+    // Sql table cache serializer.
     if (conf.getBoolean(GlutenConfig.COLUMNAR_TABLE_CACHE_ENABLED.key, defaultValue = false)) {
       conf.set(
         StaticSQLConf.SPARK_CACHE_SERIALIZER.key,
@@ -53,6 +69,13 @@ class VeloxListenerApi extends ListenerApi with Logging {
   override def onDriverShutdown(): Unit = shutdown()
 
   override def onExecutorStart(pc: PluginContext): Unit = {
+    if (!executorInitialized.compareAndSet(false, true)) {
+      // Make sure we call the static initializers only once.
+      logInfo(
+        "Skip rerunning static initializers since they are already called." +
+          " It's probably because you are creating a new SparkSession.")
+      return
+    }
     val conf = pc.conf
     if (inLocalMode(conf)) {
       // Don't do static initializations from executor side in local mode.
@@ -61,6 +84,8 @@ class VeloxListenerApi extends ListenerApi with Logging {
         "Gluten is running with Spark local mode. Skip running static initializer for executor.")
       return
     }
+
+    // Static initializers for executor.
     SparkDirectoryUtil.init(conf)
     UDFResolver.resolveUdfConf(conf, isDriver = false)
     initialize(conf)