drill-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From kkhatua <...@git.apache.org>
Subject [GitHub] drill pull request #827: DRILL-5481: Persist profiles in-memory only with a ...
Date Tue, 09 May 2017 17:13:17 GMT
Github user kkhatua commented on a diff in the pull request:

    --- Diff: exec/java-exec/src/main/java/org/apache/drill/exec/store/sys/store/EphemeralPersistentStore.java
    @@ -15,28 +15,42 @@
      * See the License for the specific language governing permissions and
      * limitations under the License.
    -package org.apache.drill.exec.testing.store;
    +package org.apache.drill.exec.store.sys.store;
     import java.util.Iterator;
     import java.util.Map;
     import java.util.concurrent.ConcurrentMap;
    +import java.util.concurrent.ConcurrentSkipListMap;
    +import java.util.concurrent.atomic.AtomicInteger;
     import java.util.concurrent.locks.ReadWriteLock;
     import java.util.concurrent.locks.ReentrantReadWriteLock;
    -import com.google.common.collect.Iterables;
    -import com.google.common.collect.Maps;
     import org.apache.drill.common.concurrent.AutoCloseableLock;
    +import org.apache.drill.exec.exception.StoreException;
     import org.apache.drill.exec.exception.VersionMismatchException;
     import org.apache.drill.exec.store.sys.BasePersistentStore;
    +import org.apache.drill.exec.store.sys.PersistentStoreConfig;
     import org.apache.drill.exec.store.sys.PersistentStoreMode;
    -import org.apache.drill.exec.store.sys.store.DataChangeVersion;
    -public class NoWriteLocalStore<V> extends BasePersistentStore<V> {
    +import com.google.common.collect.Iterables;
    +public class EphemeralPersistentStore<V> extends BasePersistentStore<V> {
    +  private static final org.slf4j.Logger logger = org.slf4j.LoggerFactory.getLogger(EphemeralPersistentStore.class);
       private final ReadWriteLock readWriteLock = new ReentrantReadWriteLock();
       private final AutoCloseableLock readLock = new AutoCloseableLock(readWriteLock.readLock());
       private final AutoCloseableLock writeLock = new AutoCloseableLock(readWriteLock.writeLock());
    -  private final ConcurrentMap<String, V> store = Maps.newConcurrentMap();
    +  private ConcurrentMap<String, V> store;
       private int version = -1;
    +  private int maxCapacity;
    +  private AtomicInteger currentSize = new AtomicInteger();
    --- End diff --
    There is already a writelock. However, with a SkipList, the call of using size() is expensive.
To minimize this computation, we have an atomic counter.  With the writeLock, if I hit the
max "virtual" capacity, I am simply inserting the latest entry and popping out the last (oldest
entry). Unlike Concurrent Queues, ConcurrentSkipListMap allows natural ordering of the keys
(which is required for serving via the WebUI).  

If your project is set up for it, you can reply to this email and have your
reply appear on GitHub as well. If your project does not have this feature
enabled and wishes so, or if the feature is enabled but not working, please
contact infrastructure at infrastructure@apache.org or file a JIRA ticket
with INFRA.

View raw message