Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

layer file creation: fatal_err on timeline dir fsync #6985

Merged
merged 7 commits into from
Mar 4, 2024
Merged

layer file creation: fatal_err on timeline dir fsync #6985

Changes from 6 commits
Commits
Show all changes
7 commits
Select commit Hold shift + click to select a range
32358cf
layer file creation: remove redundant fsync()s
problame Mar 1, 2024
ca2ed0b
layer file creation: fatal_err the timeline dir fsync
problame Mar 1, 2024
ce251ac
Merge remote-tracking branch 'origin/main' into problame/integrate-to…
problame Mar 1, 2024
c4f7a19
Merge branch 'problame/integrate-tokio-epoll-uring/layer-write-path-f…
problame Mar 1, 2024
5528b16
Merge remote-tracking branch 'origin/main' into problame/integrate-to…
problame Mar 1, 2024
c972d17
Merge branch 'problame/integrate-tokio-epoll-uring/layer-write-path-f…
problame Mar 1, 2024
00bf050
Merge branch 'main' into problame/integrate-tokio-epoll-uring/create-…
problame Mar 4, 2024
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
83 changes: 28 additions & 55 deletions pageserver/src/tenant/timeline.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -10,7 +10,7 @@ mod walreceiver;

use anyhow::{anyhow, bail, ensure, Context, Result};
use bytes::Bytes;
use camino::{Utf8Path, Utf8PathBuf};
use camino::Utf8Path;
use enumset::EnumSet;
use fail::fail_point;
use futures::stream::StreamExt;
Expand Down Expand Up @@ -50,7 +50,6 @@ use tokio_util::sync::CancellationToken;
use tracing::*;
use utils::sync::gate::{Gate, GateGuard};

use crate::pgdatadir_mapping::{AuxFilesDirectory, DirectoryKind};
use crate::tenant::timeline::logical_size::CurrentLogicalSize;
use crate::tenant::{
layer_map::{LayerMap, SearchResult},
Expand All @@ -75,6 +74,10 @@ use crate::{
disk_usage_eviction_task::EvictionCandidate, tenant::storage_layer::delta_layer::DeltaEntry,
};
use crate::{pgdatadir_mapping::LsnForTimestamp, tenant::tasks::BackgroundLoopKind};
use crate::{
pgdatadir_mapping::{AuxFilesDirectory, DirectoryKind},
virtual_file::MaybeFatalIo,
};

use crate::config::PageServerConf;
use crate::keyspace::{KeyPartitioning, KeySpace};
Expand Down Expand Up @@ -3422,30 +3425,18 @@ impl Timeline {
let _g = span.entered();
let new_delta =
Handle::current().block_on(frozen_layer.write_to_disk(&self_clone, &ctx))?;
let new_delta_path = new_delta.local_path().to_owned();

// Sync it to disk.
//
// We must also fsync the timeline dir to ensure the directory entries for
// new layer files are durable.
//
// NB: timeline dir must be synced _after_ the file contents are durable.
// So, two separate fsyncs are required, they mustn't be batched.
//
// TODO: If we're running inside 'flush_frozen_layers' and there are multiple
// files to flush, the fsync overhead can be reduces as follows:
// 1. write them all to temporary file names
// 2. fsync them
// 3. rename to the final name
// 4. fsync the parent directory.
// Note that (1),(2),(3) today happen inside write_to_disk().
// The write_to_disk() above calls writer.finish() which already did the fsync of the inodes.
// We just need to fsync the directory in which these inodes are linked,
// which we know to be the timeline directory.
//
// FIXME: the writer already fsyncs all data, only rename needs to be fsynced here
par_fsync::par_fsync(&[new_delta_path]).context("fsync of delta layer")?;
// We use fatal_err() below because the after write_to_disk returns with success,
// the in-memory state of the filesystem already has the layer file in its final place,
// and subsequent pageserver code could think it's durable while it really isn't.
par_fsync::par_fsync(&[self_clone
.conf
.timeline_path(&self_clone.tenant_shard_id, &self_clone.timeline_id)])
.context("fsync of timeline dir")?;
.fatal_err("fsync of timeline dir");

anyhow::Ok(new_delta)
}
Expand Down Expand Up @@ -3674,30 +3665,18 @@ impl Timeline {
}
}

// Sync the new layer to disk before adding it to the layer map, to make sure
// we don't garbage collect something based on the new layer, before it has
// reached the disk.
//
// We must also fsync the timeline dir to ensure the directory entries for
// new layer files are durable
//
// Compaction creates multiple image layers. It would be better to create them all
// and fsync them all in parallel.
let all_paths = image_layers
.iter()
.map(|layer| layer.local_path().to_owned())
.collect::<Vec<_>>();

par_fsync::par_fsync_async(&all_paths)
.await
.context("fsync of newly created layer files")?;

if !all_paths.is_empty() {
// The writer.finish() above already did the fsync of the inodes.
// We just need to fsync the directory in which these inodes are linked,
// which we know to be the timeline directory.
if !image_layers.is_empty() {
// We use fatal_err() below because the after writer.finish() returns with success,
// the in-memory state of the filesystem already has the layer file in its final place,
// and subsequent pageserver code could think it's durable while it really isn't.
par_fsync::par_fsync_async(&[self
.conf
.timeline_path(&self.tenant_shard_id, &self.timeline_id)])
.await
.context("fsync of timeline dir")?;
.fatal_err("fsync of timeline dir");
}

let mut guard = self.layers.write().await;
Expand Down Expand Up @@ -4279,25 +4258,19 @@ impl Timeline {
}
}

// FIXME: the writer already fsyncs all data, only rename needs to be fsynced here
let layer_paths: Vec<Utf8PathBuf> = new_layers
.iter()
.map(|l| l.local_path().to_owned())
.collect();

// Fsync all the layer files and directory using multiple threads to
// minimize latency.
par_fsync::par_fsync_async(&layer_paths)
.await
.context("fsync all new layers")?;

// The writer.finish() above already did the fsync of the inodes.
// We just need to fsync the directory in which these inodes are linked,
// which we know to be the timeline directory.
//
// We use fatal_err() below because the after writer.finish() returns with success,
// the in-memory state of the filesystem already has the layer file in its final place,
// and subsequent pageserver code could think it's durable while it really isn't.
let timeline_dir = self
.conf
.timeline_path(&self.tenant_shard_id, &self.timeline_id);

par_fsync::par_fsync_async(&[timeline_dir])
.await
.context("fsync of timeline dir")?;
.fatal_err("fsync of timeline dir");
}

stats.write_layer_files_micros = stats.read_lock_drop_micros.till_now();
Expand Down
Loading