diff --git a/coordinator/src/main/scala/filodb.coordinator/QueryActor.scala b/coordinator/src/main/scala/filodb.coordinator/QueryActor.scala
index e8bbe6f416..ae870b77ec 100644
--- a/coordinator/src/main/scala/filodb.coordinator/QueryActor.scala
+++ b/coordinator/src/main/scala/filodb.coordinator/QueryActor.scala
@@ -11,6 +11,7 @@ import akka.pattern.AskTimeoutException
 import kamon.Kamon
 import kamon.instrumentation.executor.ExecutorInstrumentation
 import kamon.tag.TagSet
+import monix.eval.Task
 import monix.execution.Scheduler
 import monix.execution.schedulers.SchedulerService
 import net.ceedubs.ficus.Ficus._
@@ -145,7 +146,6 @@ final class QueryActor(memStore: TimeSeriesStore,
           .map { res =>
             // below prevents from calling FiloDB directly (without Query Service)
             FiloSchedulers.assertThreadName(QuerySchedName)
-            querySession.close()
             replyTo ! res
             res match {
               case QueryResult(_, _, vectors, _, _, _) => resultVectors.record(vectors.length)
@@ -171,9 +171,10 @@ final class QueryActor(memStore: TimeSeriesStore,
             }
             queryExecuteSpan.finish()
           }
+          .guarantee(Task.eval(querySession.close()))
+
           logger.debug(s"Will now run query execution pipeline for $q")
           execTask.runToFuture(queryScheduler).recover { case ex =>
-            querySession.close()
             // Unhandled exception in query, should be rare
             logger.error(s"queryId ${q.queryContext.queryId} Unhandled Query Error," +
               s" query was ${q.queryContext.origQueryParams}", ex)
diff --git a/core/src/main/scala/filodb.core/query/QueryContext.scala b/core/src/main/scala/filodb.core/query/QueryContext.scala
index 94571bceaa..97b45ca9f1 100644
--- a/core/src/main/scala/filodb.core/query/QueryContext.scala
+++ b/core/src/main/scala/filodb.core/query/QueryContext.scala
@@ -156,6 +156,10 @@ object QueryContext {
   *
   * IMPORTANT: The param catchMultipleLockSetErrors should be false
   * only in unit test code for ease of use.
+  *
+  * IMPORTANT: QuerySession object should be closed after use as such
+  * `monixTask.guarantee(Task.eval(querySession.close()))`
+  *
   */
 case class QuerySession(qContext: QueryContext,
                         queryConfig: QueryConfig,
diff --git a/memory/src/main/scala/filodb.memory/EvictionLock.scala b/memory/src/main/scala/filodb.memory/EvictionLock.scala
index 67c2108425..47a58f5460 100644
--- a/memory/src/main/scala/filodb.memory/EvictionLock.scala
+++ b/memory/src/main/scala/filodb.memory/EvictionLock.scala
@@ -68,8 +68,9 @@ class EvictionLock(trackQueriesHoldingEvictionLock: Boolean = false,
   def releaseExclusive(): Unit = reclaimLock.releaseExclusive()
 
   def acquireSharedLock(timeoutMs: Long, holderId: String, promQL: String): Boolean = {
-    if (trackQueriesHoldingEvictionLock) runningQueries.put(holderId, promQL)
-    reclaimLock.tryAcquireSharedNanos(TimeUnit.MILLISECONDS.toNanos(timeoutMs))
+    val acquired = reclaimLock.tryAcquireSharedNanos(TimeUnit.MILLISECONDS.toNanos(timeoutMs))
+    if (trackQueriesHoldingEvictionLock && acquired) runningQueries.put(holderId, promQL)
+    acquired
   }
 
   def releaseSharedLock(holderId: String): Unit = {
diff --git a/query/src/main/scala/filodb/query/exec/ExecPlan.scala b/query/src/main/scala/filodb/query/exec/ExecPlan.scala
index f3a69489a1..dab0300388 100644
--- a/query/src/main/scala/filodb/query/exec/ExecPlan.scala
+++ b/query/src/main/scala/filodb/query/exec/ExecPlan.scala
@@ -92,6 +92,10 @@ trait ExecPlan extends QueryCommand {
     * The returned task can be used to perform post-execution steps
     * such as sending off an asynchronous response message etc.
     *
+    * Typically the caller creates the QuerySession parameter object. Remember
+    * that the creator is also responsible for closing it with
+    * `returnTask.guarantee(Task.eval(querySession.close()))`
+    *
     */
   // scalastyle:off method.length
   def execute(source: ChunkSource,
diff --git a/query/src/main/scala/filodb/query/exec/InProcessPlanDispatcher.scala b/query/src/main/scala/filodb/query/exec/InProcessPlanDispatcher.scala
index 1511686418..8c021bc4e5 100644
--- a/query/src/main/scala/filodb/query/exec/InProcessPlanDispatcher.scala
+++ b/query/src/main/scala/filodb/query/exec/InProcessPlanDispatcher.scala
@@ -37,7 +37,10 @@ import filodb.query.Query.qLogger
     Kamon.runWithSpan(Kamon.currentSpan(), false) {
       // translate implicit ExecutionContext to monix.Scheduler
       val querySession = QuerySession(plan.execPlan.queryContext, queryConfig, catchMultipleLockSetErrors = true)
-      plan.execPlan.execute(source, querySession).timeout(plan.clientParams.deadline.milliseconds).onErrorRecover {
+      plan.execPlan.execute(source, querySession)
+        .timeout(plan.clientParams.deadline.milliseconds)
+        .guarantee(Task.eval(querySession.close()))
+        .onErrorRecover {
         case e: TimeoutException if (plan.execPlan.queryContext.plannerParams.allowPartialResults)
         =>
           qLogger.warn(s"Swallowed TimeoutException for query id: ${plan.execPlan.queryContext.queryId} " +
diff --git a/version.sbt b/version.sbt
index 69e1694708..9af36853e1 100644
--- a/version.sbt
+++ b/version.sbt
@@ -1 +1 @@
-version in ThisBuild := "0.9.17.1"
+version in ThisBuild := "0.9.17.2"