lib/bytesutil: smooth buffer growth rate (#6761)

Before, buffer growth was always x2 of its size, which could lead to
excessive memory usage when processing big amount of data.
For example, scraping a target with hundreds of MBs in response could
result into hih memory spikes in vmagent because buffer has to double
its size to fit the response. See
https://github.com/VictoriaMetrics/VictoriaMetrics/issues/6759

The change smoothes out the growth rate, trading higher allocation rate
for lower mem usage at certain conditions.

---------

Signed-off-by: hagen1778 <roman@victoriametrics.com>
This commit is contained in:
Roman Khavronenko 2024-08-07 16:49:43 +02:00 committed by GitHub
parent 35d77a3bed
commit f28f496a9d
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2 changed files with 6 additions and 1 deletions

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@ -32,6 +32,7 @@ See also [LTS releases](https://docs.victoriametrics.com/lts-releases/).
* FEATURE: add `/influx/health` health-check handler for Influx endpoints. This is needed as some clients use the health endpoint to determine if the server is healthy and ready for data ingestion. See [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/6653) for the details.
* FEATURE: [vmctl](https://docs.victoriametrics.com/vmctl/): add `--vm-backoff-retries`, `--vm-backoff-factor`, `--vm-backoff-min-duration` and `--vm-native-backoff-retries`, `--vm-native-backoff-factor`, `--vm-native-backoff-min-duration` command-line flags. These flags allow to change backoff policy config for import requests to VictoriaMetrics. See [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/6622).
* FEATURE: [vmagent](https://docs.victoriametrics.com/vmagent/): allow overriding the `sample_limit` option at [scrape_configs](https://docs.victoriametrics.com/sd_configs/#scrape_configs) when a label `__sample_limit__` is specified for target. See [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/6665). Thanks to @zoglam for the [pull request](https://github.com/VictoriaMetrics/VictoriaMetrics/pull/6666).
* FEATURE: [vmagent](https://docs.victoriametrics.com/vmagent/): reduce memory usage when scraping targets with big response body. See [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/6759).
* BUGFIX: [vmalert](https://docs.victoriametrics.com/vmalert): respect HTTP headers defined in [notifier configuration file](https://docs.victoriametrics.com/vmalert/#notifier-configuration-file) for each request to notifiers. Previously, this param was ignored by mistake.
* BUGFIX: [stream aggregation](https://docs.victoriametrics.com/stream-aggregation/): correctly apply `-streamAggr.dropInputLabels` when global stream deduplication is enabled without `-streamAggr.config`. Previously, `-remoteWrite.streamAggr.dropInputLabels` was used instead.

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@ -65,7 +65,11 @@ func (bb *ByteBuffer) ReadFrom(r io.Reader) (int64, error) {
offset := bLen
for {
if free := len(b) - offset; free < offset {
b = slicesutil.SetLength(b, 2*len(b))
// grow slice by 30% similar to how Go does this
// https://go.googlesource.com/go/+/2dda92ff6f9f07eeb110ecbf0fc2d7a0ddd27f9d
// higher growth rates could consume excessive memory when reading big amounts of data.
n := 1.3 * float64(len(b))
b = slicesutil.SetLength(b, int(n))
}
n, err := r.Read(b[offset:])
offset += n