Zhen Ye c7b5c23ff6
enhance: filter the empty timetick from consuming side (#46541)
issue: #46540

Empty timetick is just used to sync up the time clock between different
component in milvus. So empty timetick can be ignored if we achieve the
lsn/mvcc semantic for timetick. Currently, some components need the
empty timetick to trigger some operation, such as flush/tsafe. So we
only slow down the empty time tick for 5 seconds.

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
- Core invariant: with LSN/MVCC semantics consumers only need (a) the
first timetick that advances the latest-required-MVCC to unblock
MVCC-dependent waits and (b) occasional periodic timeticks (~≤5s) for
clock synchronization—therefore frequent non-persisted empty timeticks
can be suppressed without breaking MVCC correctness.
- Logic removed/simplified: per-message dispatch/consumption of frequent
non-persisted empty timeticks is suppressed — an MVCC-aware filter
emptyTimeTickSlowdowner (internal/util/pipeline/consuming_slowdown.go)
short-circuits frequent empty timeticks in the stream pipeline
(internal/util/pipeline/stream_pipeline.go), and the WAL flusher
rate-limits non-persisted timetick dispatch to one emission per ~5s
(internal/streamingnode/server/flusher/flusherimpl/wal_flusher.go); the
delegator exposes GetLatestRequiredMVCCTimeTick to drive the filter
(internal/querynodev2/delegator/delegator.go).
- Why this does NOT introduce data loss or regressions: the slowdowner
always refreshes latestRequiredMVCCTimeTick via
GetLatestRequiredMVCCTimeTick and (1) never filters timeticks <
latestRequiredMVCCTimeTick (so existing tsafe/flush waits stay
unblocked) and (2) always lets the first timetick ≥
latestRequiredMVCCTimeTick pass to notify pending MVCC waits;
separately, WAL flusher suppression applies only to non-persisted
timeticks and still emits when the 5s threshold elapses, preserving
periodic clock-sync messages used by flush/tsafe.
- Enhancement summary (where it takes effect): adds
GetLatestRequiredMVCCTimeTick on ShardDelegator and
LastestMVCCTimeTickGetter, wires emptyTimeTickSlowdowner into
NewPipelineWithStream (internal/util/pipeline), and adds WAL flusher
rate-limiting + metrics
(internal/streamingnode/server/flusher/flusherimpl/wal_flusher.go,
pkg/metrics) to reduce CPU/dispatch overhead while keeping MVCC
correctness and periodic synchronization.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

---------

Signed-off-by: chyezh <chyezh@outlook.com>
2026-01-06 20:53:24 +08:00

80 lines
2.4 KiB
Go

// Licensed to the LF AI & Data foundation under one
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// distributed with this work for additional information
// regarding copyright ownership. The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License. You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package pipeline
import (
"github.com/milvus-io/milvus/internal/querynodev2/delegator"
base "github.com/milvus-io/milvus/internal/util/pipeline"
"github.com/milvus-io/milvus/pkg/v2/mq/msgdispatcher"
"github.com/milvus-io/milvus/pkg/v2/util/paramtable"
)
// pipeline used for querynode
type Pipeline interface {
base.StreamPipeline
GetCollectionID() UniqueID
}
type pipeline struct {
base.StreamPipeline
collectionID UniqueID
}
func (p *pipeline) GetCollectionID() UniqueID {
return p.collectionID
}
func (p *pipeline) Close() {
p.StreamPipeline.Close()
}
func NewPipeLine(
collection *Collection,
channel string,
manager *DataManager,
dispatcher msgdispatcher.Client,
delegator delegator.ShardDelegator,
) (Pipeline, error) {
collectionID := collection.ID()
pipelineQueueLength := paramtable.Get().QueryNodeCfg.FlowGraphMaxQueueLength.GetAsInt32()
p := &pipeline{
collectionID: collectionID,
StreamPipeline: base.NewPipelineWithStream(dispatcher, nodeCtxTtInterval, enableTtChecker, channel, delegator),
}
filterNode := newFilterNode(collectionID, channel, manager, delegator, pipelineQueueLength)
embeddingNode, err := newEmbeddingNode(collectionID, channel, manager, pipelineQueueLength)
if err != nil {
return nil, err
}
insertNode := newInsertNode(collectionID, channel, manager, delegator, pipelineQueueLength)
deleteNode := newDeleteNode(collectionID, channel, manager, delegator, pipelineQueueLength)
// skip add embedding node when collection has no function.
if embeddingNode != nil {
p.Add(filterNode, embeddingNode, insertNode, deleteNode)
} else {
p.Add(filterNode, insertNode, deleteNode)
}
return p, nil
}