Files
neon/pageserver/src/tenant/timeline/analysis.rs
Alex Chi Z. 700885471f fix(test): only test num of L1 layers in compaction smoke test (#9186)
close https://github.com/neondatabase/neon/issues/9160

For whatever reason, pg17's WAL pattern seems different from others,
which triggers some flaky behavior within the compaction smoke test.

## Summary of changes

* Run L0 compaction before proceeding with the read benchmark.
* So that we can ensure the num of L0 layers is 0 and test the
compaction behavior only with L1 layers.

We have a threshold for triggering L0 compaction. In some cases, the
test case did not produce enough L0 layers to do a L0 compaction,
therefore leaving the layer map with 3+ L0 layers above the L1 layers.
This increases the average read depth for the timeline.

---------

Signed-off-by: Alex Chi Z <chi@neon.tech>
2024-10-02 17:42:35 +01:00

95 lines
3.3 KiB
Rust

use std::{collections::BTreeSet, ops::Range};
use utils::lsn::Lsn;
use super::Timeline;
#[derive(serde::Serialize)]
pub(crate) struct RangeAnalysis {
start: String,
end: String,
has_image: bool,
num_of_deltas_above_image: usize,
total_num_of_deltas: usize,
num_of_l0: usize,
}
impl Timeline {
pub(crate) async fn perf_info(&self) -> Vec<RangeAnalysis> {
// First, collect all split points of the layers.
let mut split_points = BTreeSet::new();
let mut delta_ranges = Vec::new();
let mut image_ranges = Vec::new();
let num_of_l0;
let all_layer_files = {
let guard = self.layers.read().await;
num_of_l0 = guard.layer_map().unwrap().level0_deltas().len();
guard.all_persistent_layers()
};
let lsn = self.get_last_record_lsn();
for key in all_layer_files {
split_points.insert(key.key_range.start);
split_points.insert(key.key_range.end);
if key.is_delta {
delta_ranges.push((key.key_range.clone(), key.lsn_range.clone()));
} else {
image_ranges.push((key.key_range.clone(), key.lsn_range.start));
}
}
// For each split range, compute the estimated read amplification.
let split_points = split_points.into_iter().collect::<Vec<_>>();
let mut result = Vec::new();
for i in 0..(split_points.len() - 1) {
let start = split_points[i];
let end = split_points[i + 1];
// Find the latest image layer that contains the information.
let mut maybe_image_layers = image_ranges
.iter()
// We insert split points for all image layers, and therefore a `contains` check for the start point should be enough.
.filter(|(key_range, img_lsn)| key_range.contains(&start) && img_lsn <= &lsn)
.cloned()
.collect::<Vec<_>>();
maybe_image_layers.sort_by(|a, b| a.1.cmp(&b.1));
let image_layer = maybe_image_layers.last().cloned();
let lsn_filter_start = image_layer
.as_ref()
.map(|(_, lsn)| *lsn)
.unwrap_or(Lsn::INVALID);
fn overlaps_with(lsn_range_a: &Range<Lsn>, lsn_range_b: &Range<Lsn>) -> bool {
!(lsn_range_a.end <= lsn_range_b.start || lsn_range_a.start >= lsn_range_b.end)
}
let maybe_delta_layers = delta_ranges
.iter()
.filter(|(key_range, lsn_range)| {
key_range.contains(&start) && overlaps_with(&(lsn_filter_start..lsn), lsn_range)
})
.cloned()
.collect::<Vec<_>>();
let pitr_delta_layers = delta_ranges
.iter()
.filter(|(key_range, _)| key_range.contains(&start))
.cloned()
.collect::<Vec<_>>();
result.push(RangeAnalysis {
start: start.to_string(),
end: end.to_string(),
has_image: image_layer.is_some(),
num_of_deltas_above_image: maybe_delta_layers.len(),
total_num_of_deltas: pitr_delta_layers.len(),
num_of_l0,
});
}
result
}
}