Github user marmbrus commented on a diff in the pull request:
https://github.com/apache/spark/pull/2887#discussion_r19513208
--- 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 --
We should consider initializing the session state in the constructor, maybe
by forcing the realization of the lazy val. Matei just bumped into a problem
where running "SHOW TABLES" as the first command null pointers. Lets make sure
that this PR fixes those sorts of problems too.
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