Github user zhzhan commented on a diff in the pull request:
https://github.com/apache/spark/pull/2887#discussion_r19443373
--- Diff:
sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveContext.scala ---
@@ -223,21 +223,23 @@ class HiveContext(sc: SparkContext) extends
SQLContext(sc) {
}
/**
- * SQLConf and HiveConf contracts: when the hive session is first
initialized, params in
- * HiveConf will get picked up by the SQLConf. Additionally, any
properties set by
- * set() or a SET command inside sql() will be set in the SQLConf *as
well as*
- * in the HiveConf.
+ * SQLConf and HiveConf contracts:
+ *
+ * 1. reuse existing started SessionState if any
+ * 2. when the Hive session is first initialized, params in HiveConf
will get picked up by the
+ * SQLConf. Additionally, any properties set by set() or a SET
command inside sql() will be
+ * set in the SQLConf *as well as* in the HiveConf.
*/
- @transient protected[hive] lazy val hiveconf = new
HiveConf(classOf[SessionState])
- @transient protected[hive] lazy val sessionState = {
- val ss = new SessionState(hiveconf)
- setConf(hiveconf.getAllProperties) // Have SQLConf pick up the
initial set of HiveConf.
- SessionState.start(ss)
- ss.err = new PrintStream(outputBuffer, true, "UTF-8")
- ss.out = new PrintStream(outputBuffer, true, "UTF-8")
-
- ss
- }
+ @transient protected[hive] lazy val (hiveconf, sessionState) =
+ Option(SessionState.get())
+ .orElse(Some(new SessionState(new HiveConf(classOf[SessionState]))))
+ .map { state =>
+ setConf(state.getConf.getAllProperties)
+ if (state.out == null) state.out = new PrintStream(outputBuffer,
true, "UTF-8")
+ if (state.err == null) state.err = new PrintStream(outputBuffer,
true, "UTF-8")
+ (state.getConf, state)
+ }
+ .get
--- End diff --
Should SessionState.start(state) be invoked here? Otherwise, it relies on
other code to initialize the state, and we lose the track whether the state is
initialized, and other code may call SessionState.start() multiple times,
resulting in unexpected behavior. Correct me if I am wrong.
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