FrankChen021 commented on code in PR #19477:
URL: https://github.com/apache/druid/pull/19477#discussion_r3294102129
##########
indexing-service/src/main/java/org/apache/druid/indexing/overlord/supervisor/SupervisorManager.java:
##########
@@ -393,6 +374,120 @@ public boolean resetSupervisor(String id, @Nullable
DataSourceMetadata resetData
return true;
}
+ /**
+ * Resets a supervisor to the latest stream offsets and starts a bounded
backfill supervisor to
+ * process the skipped range from the previously checkpointed offsets up to
the latest offsets.
+ *
+ * @param id supervisor ID
+ * @param backfillTaskCount number of tasks for the backfill supervisor, or
null to inherit from the source spec
+ * @return map with {@code "id"} (the original supervisor ID) and {@code
"backfillSupervisorId"}
+ * @throws IllegalArgumentException if the supervisor is not a {@link
SeekableStreamSupervisor},
+ * if {@code useEarliestSequenceNumber} is
true,
+ * if {@code useConcurrentLocks} is not set
to true in the supervisor context,
+ * or if the supervisor is not in a RUNNING
state
+ * @throws IllegalStateException if the latest or checkpointed offsets
cannot be retrieved,
+ * or if the backfill spec cannot be
serialized
+ */
+ public Map<String, Object> resetSupervisorAndBackfill(String id, @Nullable
Integer backfillTaskCount)
+ {
+ Preconditions.checkState(started, "SupervisorManager not started");
+ Preconditions.checkNotNull(id, "id");
+
+ Pair<Supervisor, SupervisorSpec> supervisorPair = supervisors.get(id);
+ validateResetAndBackfill(id, supervisorPair);
+
+ SeekableStreamSupervisor streamSupervisor = (SeekableStreamSupervisor)
supervisorPair.lhs;
+ SeekableStreamSupervisorSpec streamSpec = (SeekableStreamSupervisorSpec)
supervisorPair.rhs;
+
+ log.info("Capturing latest offsets from stream for supervisor[%s]", id);
+ streamSupervisor.updatePartitionLagFromStream();
+ Map<?, ?> endOffsets = streamSupervisor.getLatestSequencesFromStream();
+
+ log.info("Capturing checkpointed offsets for supervisor[%s]", id);
+ Map<?, ?> startOffsets = streamSupervisor.getOffsetsFromMetadataStorage();
+
+ if (endOffsets == null || endOffsets.isEmpty()) {
+ throw new ISE("Skipping reset: Failed to get latest offsets from stream
for supervisor[%s]", id);
+ }
+ if (startOffsets == null || startOffsets.isEmpty()) {
+ throw new ISE("Skipping reset: Failed to get checkpointed offsets for
supervisor[%s]", id);
+ }
+
+ String backfillSupervisorId = IdUtils.getRandomIdWithPrefix(id +
"_backfill");
+
+ try {
+ Map<String, Object> normalizedStartOffsets =
jsonMapper.readValue(jsonMapper.writeValueAsString(startOffsets), Map.class);
+ Map<String, Object> normalizedEndOffsets =
jsonMapper.readValue(jsonMapper.writeValueAsString(endOffsets), Map.class);
+ BoundedStreamConfig boundedStreamConfig = new
BoundedStreamConfig(normalizedStartOffsets, normalizedEndOffsets);
+ SupervisorSpec backfillSpec = createBackfillSpec(streamSpec,
backfillSupervisorId, boundedStreamConfig, backfillTaskCount);
+ createOrUpdateAndStartSupervisor(backfillSpec);
+ }
+ catch (JsonProcessingException e) {
+ throw new ISE(e, "Failed to create backfill supervisor spec for
supervisor[%s]", id);
+ }
+
+ log.info("Started backfill supervisor[%s] for supervisor[%s]",
backfillSupervisorId, id);
+
+ log.info("Resetting supervisor[%s] metadata to latest offsets", id);
+ DataSourceMetadata resetMetadata =
streamSupervisor.createDataSourceMetaDataForReset(
+ streamSupervisor.getIoConfig().getStream(),
+ endOffsets
+ );
+
+ streamSupervisor.resetOffsets(resetMetadata);
Review Comment:
Thanks for adding `resetOffsetsForwardOnly`; it handles the common case
where the checkpoint has already advanced by the time the reset notice reads
metadata. I still think the rollback race is not fully closed, though:
`resetOffsetsInternal` reads current metadata, computes the max map, then calls
`resetDataSourceMetadata`, and that storage method does an unconditional
`UPDATE ... WHERE dataSource = :dataSource`. If a task publishes/checkpoints
after the read but before that update, the max is computed from stale metadata
and the reset can still overwrite the newer checkpoint. So I would keep this
open unless the reset write is CAS/retried against the metadata it read, or the
main supervisor is quiesced before capturing/resetting. I agree the
backfill-overlap duplicate case is separate and requires either
accepting/documenting possible duplicates or suspending the main supervisor.
Reviewed 17 of 17 changed files.
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