cloud-fan commented on a change in pull request #24028: [SPARK-26917][SQL]
Further reduce locks in CacheManager
URL: https://github.com/apache/spark/pull/24028#discussion_r265207871
##########
File path:
sql/core/src/main/scala/org/apache/spark/sql/execution/CacheManager.scala
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@@ -46,38 +45,17 @@ case class CachedData(plan: LogicalPlan,
cachedRepresentation: InMemoryRelation)
*/
class CacheManager extends Logging {
- @transient
- private val cachedData = new java.util.LinkedList[CachedData]
-
- @transient
- private val cacheLock = new ReentrantReadWriteLock
-
- /** Acquires a read lock on the cache for the duration of `f`. */
- private def readLock[A](f: => A): A = {
- val lock = cacheLock.readLock()
- lock.lock()
- try f finally {
- lock.unlock()
- }
- }
-
- /** Acquires a write lock on the cache for the duration of `f`. */
- private def writeLock[A](f: => A): A = {
- val lock = cacheLock.writeLock()
- lock.lock()
- try f finally {
- lock.unlock()
- }
- }
+ @transient @volatile
+ private var cachedData = IndexedSeq[CachedData]()
Review comment:
we'd better add some comments to explain the access pattern of `cachedData`.
e.g. adding/removing elements should be done by creating a new seq, and locked
by this.
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