When ingesting samples with the same labels(duplicated samples or
samples with the same labels after `by` or `without` options). They
could register different entries for the same labelset in
LabelsCompressor.
For example, both index 99 and 100 can be assigned to label `foo=1` in
two concurrent pushes. Then due to differing label indexes in encoded
keys, the samples will appear as distinct in aggrState, resulting in
duplicated results after decompressing the label indexes.
fbde238cdc/lib/streamaggr/streamaggr.go (L933)
In this pull request, since we need to store `idxToLabel` first to
ensure the idx can be searched after `lc.labelToIdxStore`,
the `lc.idxToLabel` still could contain a duplicated entries
[100]="foo=1". But given the low likelihood of this issue and the size
of idxToLabel, it should be fine.
Change the return values for these functions - now they return the unmarshaled result plus
the size of the unmarshaled result in bytes, so the caller could re-slice the src for further unmarshaling.
This improves performance of these functions in hot loops of VictoriaLogs a bit.
The labelsMap struct employs the fact that label indexes are condensed around 0,
so it stores the referred labels in a slice instead of map and uses slice index as label key.
This allows increasing the LabelsCompressor.Decompress performance by up to 3x.
This also reduces the latency of data flush in stream aggregation.
- Reduce memory usage by up to 5x when de-duplicating samples across big number of time series.
- Reduce memory usage by up to 5x when aggregating across big number of output time series.
- Add lib/promutils.LabelsCompressor, which is going to be used by other VictoriaMetrics components
for reducing memory usage for marshaled []prompbmarshal.Label.
- Add `dedup_interval` option at aggregation config, which allows setting individual
deduplication intervals per each aggregation.
- Add `keep_metric_names` option at aggregation config, which allows keeping the original
metric names in the output samples.
- Add `unique_samples` output, which counts the number of unique sample values.
- Add `increase_prometheus` and `total_prometheus` outputs, which ignore the first sample
per each newly encountered time series.
- Use 64-bit hashes instead of marshaled labels as map keys when calculating `count_series` output.
This makes obsolete https://github.com/VictoriaMetrics/VictoriaMetrics/pull/5579
- Expose various metrics, which may help debugging stream aggregation:
- vm_streamaggr_dedup_state_size_bytes - the size of data structures responsible for deduplication
- vm_streamaggr_dedup_state_items_count - the number of items in the deduplication data structures
- vm_streamaggr_labels_compressor_size_bytes - the size of labels compressor data structures
- vm_streamaggr_labels_compressor_items_count - the number of entries in the labels compressor
- vm_streamaggr_flush_duration_seconds - a histogram, which shows the duration of stream aggregation flushes
- vm_streamaggr_dedup_flush_duration_seconds - a histogram, which shows the duration of deduplication flushes
- vm_streamaggr_flush_timeouts_total - counter for timed out stream aggregation flushes,
which took longer than the configured interval
- vm_streamaggr_dedup_flush_timeouts_total - counter for timed out deduplication flushes,
which took longer than the configured dedup_interval
- Actualize docs/stream-aggregation.md
The memory usage reduction increases CPU usage during stream aggregation by up to 30%.
This commit is based on https://github.com/VictoriaMetrics/VictoriaMetrics/pull/5850
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5898
