ankitsultana commented on code in PR #10322:
URL: https://github.com/apache/pinot/pull/10322#discussion_r1128158528
##########
pinot-query-runtime/src/main/java/org/apache/pinot/query/mailbox/GrpcMailboxService.java:
##########
@@ -18,45 +18,62 @@
*/
package org.apache.pinot.query.mailbox;
+import com.google.common.cache.Cache;
+import com.google.common.cache.CacheBuilder;
+import com.google.common.cache.RemovalListener;
+import com.google.common.cache.RemovalNotification;
import io.grpc.ManagedChannel;
-import io.grpc.stub.StreamObserver;
-import java.util.concurrent.ConcurrentHashMap;
-import java.util.concurrent.CountDownLatch;
+import java.time.Duration;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.TimeUnit;
import java.util.function.Consumer;
-import org.apache.pinot.common.proto.Mailbox;
+import javax.annotation.Nullable;
import org.apache.pinot.common.proto.PinotMailboxGrpc;
import org.apache.pinot.query.mailbox.channel.ChannelManager;
import org.apache.pinot.query.mailbox.channel.MailboxStatusStreamObserver;
import org.apache.pinot.query.runtime.blocks.TransferableBlock;
import org.apache.pinot.spi.env.PinotConfiguration;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
/**
- * GRPC-based implementation of {@link MailboxService}.
+ * GRPC-based implementation of {@link MailboxService}. Note that there can be
cases where the ReceivingMailbox
+ * and/or the underlying connection can be leaked:
*
- * <p>It maintains a collection of connected mailbox servers and clients to
remote hosts. All indexed by the
- * mailboxID in the format of:
<code>"jobId:partitionKey:senderHost:senderPort:receiverHost:receiverPort"</code>
+ * <ol>
+ * <li>When the OpChain corresponding to the receiver was never
registered.</li>
+ * <li>When the receiving OpChain exited before data was sent for the first
time by the sender.</li>
+ * </ol>
*
- * <p>Connections are established/initiated from the sender side and only
tier-down from the sender side as well.
- * In the event of exception or timed out, the connection is cloased based on
a mutually agreed upon timeout period
- * after the last successful message sent/received.
- *
- * <p>Noted that:
- * <ul>
- * <li>the latter part of the mailboxID consist of the channelID.</li>
- * <li>the job_id should be uniquely identifying a send/receving pair, for
example if one bundle job requires
- * to open 2 mailboxes, they should use {job_id}_1 and {job_id}_2 to
distinguish the 2 different mailbox.</li>
- * </ul>
+ * To handle these cases, we store the {@link ReceivingMailbox} entries in a
time-expiring cache. If there was a
+ * leak, the entry would be evicted, and in that case we also issue a cancel
to ensure the underlying stream is also
+ * released.
*/
public class GrpcMailboxService implements MailboxService<TransferableBlock> {
+ private static final Logger LOGGER =
LoggerFactory.getLogger(GrpcMailboxService.class);
// channel manager
+ private static final Duration DANGLING_RECEIVING_MAILBOX_EXPIRY =
Duration.ofMinutes(5);
private final ChannelManager _channelManager;
private final String _hostname;
private final int _mailboxPort;
- // maintaining a list of registered mailboxes.
- private final ConcurrentHashMap<String, ReceivingMailbox<TransferableBlock>>
_receivingMailboxMap =
- new ConcurrentHashMap<>();
+ // We use a cache to ensure that the receiving mailbox and the underlying
gRPC stream are not leaked in the cases
+ // where the corresponding OpChain is either never registered or died before
the sender sent data for the first time.
+ private final Cache<String, GrpcReceivingMailbox> _receivingMailboxCache =
+
CacheBuilder.newBuilder().expireAfterAccess(DANGLING_RECEIVING_MAILBOX_EXPIRY.toMinutes(),
TimeUnit.MINUTES)
+ .removalListener(new RemovalListener<String, GrpcReceivingMailbox>()
{
+ @Override
+ public void onRemoval(RemovalNotification<String,
GrpcReceivingMailbox> notification) {
+ if (notification.wasEvicted()) {
+ // TODO: This should be tied with query deadline, but for that
we need to know the query deadline
+ // when the GrpcReceivingMailbox is initialized in
MailboxContentStreamObserver.
+ LOGGER.info("Removing dangling GrpcReceivingMailbox: {}",
notification.getKey());
+ notification.getValue().cancel();
Review Comment:
Yeah that's required. I'll add it to the interface javadoc.
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