## Problem
Two recently observed log errors indicate safekeeper tasks for a
timeline running after that timeline's deletion has started.
- https://github.com/neondatabase/neon/issues/8972
- https://github.com/neondatabase/neon/issues/8974
These code paths do not have a mechanism that coordinates task shutdown
with the overall shutdown of the timeline.
## Summary of changes
- Add a `Gate` to `Timeline`
- Take the gate as part of resident timeline guard: any code that holds
a guard over a timeline staying resident should also hold a guard over
the timeline's total lifetime.
- Take the gate from the wal removal task
- Respect Timeline::cancel in WAL send/recv code, so that we do not
block shutdown indefinitely.
- Add a test that deletes timelines with open pageserver+compute
connections, to check these get torn down as expected.
There is some risk to introducing gates: if there is code holding a gate
which does not properly respect a cancellation token, it can cause
shutdown hangs. The risk of this for safekeepers is lower in practice
than it is for other services, because in a healthy timeline deletion,
the compute is shutdown first, then the timeline is deleted on the
pageserver, and finally it is deleted on the safekeepers -- that makes
it much less likely that some protocol handler will still be running.
Closes: #8972Closes: #8974
`download_byte_range()` is basically a copy of `download()` with an
additional option passed to the backend SDKs. This can cause these code
paths to diverge, and prevents combining various options.
This patch adds `DownloadOpts::byte_(start|end)` and move byte range
handling into `download()`.
Endpoint implementation sends msg to manager requesting to do the
reset. Manager stops current partial backup upload task if it exists and
performs the reset.
Also slightly tweak eviction condition: all full segments before
flush_lsn must be uploaded (and committed) and there must be only one
segment left on disk (partial). This allows to evict timelines which
started not on the first segment and didn't fill the whole
segment (previous condition wasn't good because last_removed_segno was
0).
ref https://github.com/neondatabase/neon/issues/8759
## Problem
The control file contains the id of the safekeeper that uploaded it.
Previously, when sending a snapshot of the control file to another sk,
it would eventually be gc-ed by the receiving sk. This is incorrect
because the original sk might still need it later.
## Summary of Changes
When sending a snapshot and the control file contains an uploaded
segment:
* Create a copy of the segment in s3 with the destination sk in the
object name
* Tweak the streamed control file to point to the object create in the
previous step
Note that the snapshot endpoint now has to know the id of the requestor,
so the api has been extended to include the node if of the destination
sk.
Closes https://github.com/neondatabase/neon/issues/8542
## Problem
The scrubber would like to check the highest mtime in a tenant's objects
as a safety check during purges. It recently switched to use
GenericRemoteStorage, so we need to expose that in the listing methods.
## Summary of changes
- In Listing.keys, return a ListingObject{} including a last_modified
field, instead of a RemotePath
---------
Co-authored-by: Arpad Müller <arpad-m@users.noreply.github.com>
PR #8299 has switched the storage scrubber to use
`DefaultCredentialsChain`. Now we do this for `remote_storage`, as it
allows us to use `remote_storage` from inside kubernetes. Most of the
diff is due to `GenericRemoteStorage::from_config` becoming `async fn`.
## Problem
new clippy warnings on nightly.
## Summary of changes
broken up each commit by warning type.
1. Remove some unnecessary refs.
2. In edition 2024, inference will default to `!` and not `()`.
3. Clippy complains about doc comment indentation
4. Fix `Trait + ?Sized` where `Trait: Sized`.
5. diesel_derives triggering `non_local_defintions`
Fixes https://github.com/neondatabase/neon/issues/6337
Add safekeeper support to switch between `Present` and
`Offloaded(flush_lsn)` states. The offloading is disabled by default,
but can be controlled using new cmdline arguments:
```
--enable-offload
Enable automatic switching to offloaded state
--delete-offloaded-wal
Delete local WAL files after offloading. When disabled, they will be left on disk
--control-file-save-interval <CONTROL_FILE_SAVE_INTERVAL>
Pending updates to control file will be automatically saved after this interval [default: 300s]
```
Manager watches state updates and detects when there are no actvity on
the timeline and actual partial backup upload in remote storage. When
all conditions are met, the state can be switched to offloaded.
In `timeline.rs` there is `StateSK` enum to support switching between
states. When offloaded, code can access only control file structure and
cannot use `SafeKeeper` to accept new WAL.
`FullAccessTimeline` is now renamed to `WalResidentTimeline`. This
struct contains guard to notify manager about active tasks requiring
on-disk WAL access. All guards are issued by the manager, all requests
are sent via channel using `ManagerCtl`. When manager receives request
to issue a guard, it unevicts timeline if it's currently evicted.
Fixed a bug in partial WAL backup, it used `term` instead of
`last_log_term` previously.
After this commit is merged, next step is to roll this change out, as in
issue #6338.
This is a preparation for
https://github.com/neondatabase/neon/issues/6337.
The idea is to add FullAccessTimeline, which will act as a guard for
tasks requiring access to WAL files. Eviction will be blocked on these
tasks and WAL won't be deleted from disk until there is at least one
active FullAccessTimeline.
To get FullAccessTimeline, tasks call `tli.full_access_guard().await?`.
After eviction is implemented, this function will be responsible for
downloading missing WAL file and waiting until the download finishes.
This commit also contains other small refactorings:
- Separate `get_tenant_dir` and `get_timeline_dir` functions for
building a local path. This is useful for looking at usages and finding
tasks requiring access to local filesystem.
- `timeline_manager` is now responsible for spawning all background
tasks
- WAL removal task is now spawned instantly after horizon is updated
In safekeepers we have several background tasks. Previously `WAL backup`
task was spawned by another task called `wal_backup_launcher`. That task
received notifications via `wal_backup_launcher_rx` and decided to spawn
or kill existing backup task associated with the timeline. This was
inconvenient because each code segment that touched shared state was
responsible for pushing notification into `wal_backup_launcher_tx`
channel. This was error prone because it's easy to miss and could lead
to deadlock in some cases, if notification pushing was done in the wrong
order.
We also had a similar issue with `is_active` timeline flag. That flag
was calculated based on the state and code modifying the state had to
call function to update the flag. We had a few bugs related to that,
when we forgot to update `is_active` flag in some places where it could
change.
To fix these issues, this PR adds a new `timeline_manager` background
task associated with each timeline. This task is responsible for
managing all background tasks, including `is_active` flag which is used
for pushing broker messages. It is subscribed for updates in timeline
state in a loop and decides to spawn/kill background tasks when needed.
There is a new structure called `TimelinesSet`. It stores a set of
`Arc<Timeline>` and allows to copy the set to iterate without holding
the mutex. This is what replaced `is_active` flag for the broker. Now
broker push task holds a reference to the `TimelinesSet` with active
timelines and use it instead of iterating over all timelines and
filtering by `is_active` flag.
Also added some metrics for manager iterations and active backup tasks.
Ideally manager should be doing not too many iterations and we should
not have a lot of backup tasks spawned at the same time.
Fixes#7751
---------
Co-authored-by: Arseny Sher <sher-ars@yandex.ru>
## Problem
Split off from https://github.com/neondatabase/neon/pull/7399, which is
the first piece of code that does a WithDelimiter object listing using a
prefix that isn't a full directory name.
## Summary of changes
- Revise list function to not append a `/` to the prefix -- prefixes
don't have to end with a slash.
- Fix local_fs implementation of list to not assume that WithDelimiter
case will always use a directory as a prerfix.
- Remove `list_files`, `list_prefixes` wrappers, as they add little
value and obscure the underlying list function -- we need callers to
understand the semantics of what they're really calling (listobjectsv2)
Add support for backing up partial segments to remote storage. Disabled
by default, can be enabled with `--partial-backup-enabled`.
Safekeeper timeline has a background task which is subscribed to
`commit_lsn` and `flush_lsn` updates. After the partial segment was
updated (`flush_lsn` was changed), the segment will be uploaded to S3 in
about 15 minutes.
The filename format for partial segments is
`Segment_Term_Flush_Commit_skNN.partial`, where:
- `Segment` – the segment name, like `000000010000000000000001`
- `Term` – current term
- `Flush` – flush_lsn in hex format `{:016X}`, e.g. `00000000346BC568`
- `Commit` – commit_lsn in the same hex format
- `NN` – safekeeper_id, like `1`
The full object name example:
`000000010000000000000002_2_0000000002534868_0000000002534410_sk1.partial`
Each safekeeper will keep info about remote partial segments in its
control file. Code updates state in the control file before doing any S3
operations. This way control file stores information about all
potentially existing remote partial segments and can clean them up after
uploading a newer version.
Closes#6336
Cancellation and timeouts are handled at remote_storage callsites, if
they are. However they should always be handled, because we've had
transient problems with remote storage connections.
- Add cancellation token to the `trait RemoteStorage` methods
- For `download*`, `list*` methods there is
`DownloadError::{Cancelled,Timeout}`
- For the rest now using `anyhow::Error`, it will have root cause
`remote_storage::TimeoutOrCancel::{Cancel,Timeout}`
- Both types have `::is_permanent` equivalent which should be passed to
`backoff::retry`
- New generic RemoteStorageConfig option `timeout`, defaults to 120s
- Start counting timeouts only after acquiring concurrency limiter
permit
- Cancellable permit acquiring
- Download stream timeout or cancellation is communicated via an
`std::io::Error`
- Exit backoff::retry by marking cancellation errors permanent
Fixes: #6096Closes: #4781
Co-authored-by: arpad-m <arpad-m@users.noreply.github.com>
Do list-delete operations in batches instead of doing full list first, to ensure
deletion makes progress even if there are a lot of files to remove.
To this end, add max_keys limit to remote storage list_files.
The solution we ended up for `backoff::retry` requires always cloning of
cancellation tokens even though there is just `.await`. Fix that, and
also turn the return type into `Option<Result<T, E>>` avoiding the need
for the `E::cancelled()` fn passed in.
Cc: #6096
In the most straightforward way; safekeeper performs it in DELETE endpoint
implementation, with no coordination between sks.
delete_force endpoint in the code is renamed to delete as there is only one way
to delete.
Implement API for cloning a single timeline inside a safekeeper. Also
add API for calculating a sha256 hash of WAL, which is used in tests.
`/copy` API works by copying objects inside S3 for all but the last
segments, and the last segments are copied on-disk. A special temporary
directory is created for a timeline, because copy can take a lot of
time, especially for large timelines. After all files segments have been
prepared, this directory is mounted to the main tree and timeline is
loaded to memory.
Some caveats:
- large timelines can take a lot of time to copy, because we need to
copy many S3 segments
- caller should wait for HTTP call to finish indefinetely and don't
close the HTTP connection, because it will stop the process, which is
not continued in the background
- `until_lsn` must be a valid LSN, otherwise bad things can happen
- API will return 200 if specified `timeline_id` already exists, even if
it's not a copy
- each safekeeper will try to copy S3 segments, so it's better to not
call this API in-parallel on different safekeepers
Currently using 8kB buffers, raise that to 32kB to hopefully 1/4 of
`spawn_blocking` usage. Also a drive-by fixing of last `tokio::io::copy`
to `tokio::io::copy_buf`.
There is double buffering in remote_storage and in pageserver for 8KiB
in using `tokio::io::copy` to read `BufReader<ReaderStream<_>>`.
Switches downloads and uploads to use `Stream<Item =
std::io::Result<Bytes>>`. Caller and only caller now handles setting up
buffering. For reading, `Stream<Item = ...>` is also a `AsyncBufRead`,
so when writing to a file, we now have `tokio::io::copy_buf` reading
full buffers and writing them to `tokio::io::BufWriter` which handles
the buffering before dispatching over to `tokio::fs::File`.
Additionally implements streaming uploads for azure. With azure
downloads are a bit nicer than before, but not much; instead of one huge
vec they just hold on to N allocations we got over the wire.
This PR will also make it trivial to switch reading and writing to
io-uring based methods.
Cc: #5563.
Fixes#4689 by replacing all of `std::Path` , `std::PathBuf` with
`camino::Utf8Path`, `camino::Utf8PathBuf` in
- pageserver
- safekeeper
- control_plane
- libs/remote_storage
Co-authored-by: Joonas Koivunen <joonas@neon.tech>
This is a full switch, fs io operations are also tokio ones, working through
thread pool. Similar to pageserver, we have multiple runtimes for easier `top`
usage and isolation.
Notable points:
- Now that guts of safekeeper.rs are full of .await's, we need to be very
careful not to drop task at random point, leaving timeline in unclear
state. Currently the only writer is walreceiver and we don't have top
level cancellation there, so we are good. But to be safe probably we should
add a fuse panicking if task is being dropped while operation on a timeline
is in progress.
- Timeline lock is Tokio one now, as we do disk IO under it.
- Collecting metrics got a crutch: since prometheus Collector is
synchronous, it spawns a thread with current thread runtime collecting data.
- Anything involving closures becomes significantly more complicated, as
async fns are already kinda closures + 'async closures are unstable'.
- Main thread now tracks other main tasks, which got much easier.
- The only sync place left is initial data loading, as otherwise clippy
complains on timeline map lock being held across await points -- which is
not bad here as it happens only in single threaded runtime of main thread.
But having it sync doesn't hurt either.
I'm concerned about performance of thread pool io offloading, async traits and
many await points; but we can try and see how it goes.
fixes https://github.com/neondatabase/neon/issues/3036
fixes https://github.com/neondatabase/neon/issues/3966
Add `wal_backup_parallel_jobs` cmdline argument to specify the max count
of parallel segments upload. New default value is 5, meaning that
safekeepers will try to upload 5 segments concurrently if they are
available. Setting this value to 1 will be equivalent to the sequential
upload that we had before.
Part of the https://github.com/neondatabase/neon/issues/3957
Add essential safekeeper and pageserver::walreceiver metrics. Mostly
counters, such as the number of received queries, broker messages,
removed WAL segments, or connection switches events in walreceiver.
Also logs broker push loop duration.
Otherwise it can lag a lot, preventing WAL segments cleanup. Also max
wal_backup_lsn on update, pulling it down is pointless.
Should help with https://github.com/neondatabase/neon/issues/3957, but
will not fix it completely.
- Add support for splitting async postgres_backend into read and write halfes.
Safekeeper needs this for bidirectional streams. To this end, encapsulate
reading-writing postgres messages to framed.rs with split support without any
additional changes (relying on BufRead for reading and BytesMut out buffer for
writing).
- Use async postgres_backend throughout safekeeper (and in proxy auth link
part).
- In both safekeeper COPY streams, do read-write from the same thread/task with
select! for easier error handling.
- Tidy up finishing CopyBoth streams in safekeeper sending and receiving WAL
-- join split parts back catching errors from them before returning.
Initially I hoped to do that read-write without split at all, through polling
IO:
https://github.com/neondatabase/neon/pull/3522
However that turned out to be more complicated than I initially expected
due to 1) borrow checking and 2) anon Future types. 1) required Rc<Refcell<...>>
which is Send construct just to satisfy the checker; 2) can be workaround with
transmute. But this is so messy that I decided to leave split.
1.66 release speeds up compile times for over 10% according to tests.
Also its Clippy finds plenty of old nits in our code:
* useless conversion, `foo as u8` where `foo: u8` and similar, removed
`as u8` and similar
* useless references and dereferenced (that were automatically adjusted
by the compiler), removed various `&` and `*`
* bool -> u8 conversion via `if/else`, changed to `u8::from`
* Map `.iter()` calls where only values were used, changed to
`.values()` instead
Standing out lints:
* `Eq` is missing in our protoc generated structs. Silenced, does not
seem crucial for us.
* `fn default` looks like the one from `Default` trait, so I've
implemented that instead and replaced the `dummy_*` method in tests with
`::default()` invocation
* Clippy detected that
```
if retry_attempt < u32::MAX {
retry_attempt += 1;
}
```
is a saturating add and proposed to replace it.
Changes:
* Remove `RemoteObjectId` concept from remote_storage.
Operate directly on /-separated names instead.
These names are now represented by struct `RemotePath` which was renamed from struct `RelativePath`
* Require remote storage to operate on relative paths for its contents, thus simplifying the way to derive them in pageserver and safekeeper
* Make `IndexPart` to use `String` instead of `RelativePath` for its entries, since those are just the layer names
This API is rather pointless, as sane choice anyway requires knowledge of peers
status and leaders lifetime in any case can intersect, which is fine for us --
so manual elections are straightforward. Here, we deterministically choose among
the reasonably caught up safekeepers, shifting by timeline id to spread the
load.
A step towards custom broker https://github.com/neondatabase/neon/issues/2394
- Split postgres_ffi into two version specific files.
- Preserve pg_version in timeline metadata.
- Use pg_version in safekeeper code. Check for postgres major version mismatch.
- Clean up the code to use DEFAULT_PG_VERSION constant everywhere, instead of hardcoding.
- Parameterize python tests: use DEFAULT_PG_VERSION env and pg_version fixture.
To run tests using a specific PostgreSQL version, pass the DEFAULT_PG_VERSION environment variable:
'DEFAULT_PG_VERSION='15' ./scripts/pytest test_runner/regress'
Currently don't all tests pass, because rust code relies on the default version of PostgreSQL in a few places.
We had a pattern like this:
match remote_storage {
GenericRemoteStorage::Local(storage) => {
let source = storage.remote_object_id(&file_path)?;
...
storage
.function(&source, ...)
.await
},
GenericRemoteStorage::S3(storage) => {
... exact same code as for the Local case ...
},
This removes the code duplication, by allowing you to call the functions
directly on GenericRemoteStorage.
Also change RemoveObjectId to be just a type alias for String. Now that
the callers of GenericRemoteStorage functions don't know whether they're
dealing with the LocalFs or S3 implementation, RemoveObjectId must be the
same type for both.
Another preparatory commit for pg15 support:
* generate bindings for both pg14 and pg15;
* update Makefile and CI scripts: now neon build depends on both PostgreSQL versions;
* some code refactoring to decrease version-specific dependencies.
Re-export only things that are used by other modules.
In the future, I'm imagining that we run bindgen twice, for Postgres
v14 and v15. The two sets of bindings would go into separate
'bindings_v14' and 'bindings_v15' modules.
Rearrange postgres_ffi modules.
Move function, to avoid Postgres version dependency in timelines.rs
Move function to generate a logical-message WAL record to postgres_ffi.
I made the check at launcher level with the perspective of generally moving
election (decision who offloads) there.
Also log timeline 'active' changes.
I still don't like the surroundings and feel we'd better get away without using
election API at all, but this is a quick fix to keep CI green.
ref #1815
- Uncomment accidently `self.keep_alive.abort()` commented line, due to this
task never finished, which blocked launcher.
- Mess up with initialization one more time, to fix offloader trying to back up
segment 0. Now we initialize all required LSNs in handle_elected,
where we learn start LSN for the first time.
- Fix blind attempt to provide safekeeper service file with remote storage
params.
