There were some incompatible changes. Most churn was from switching from
the now-deprecated fcntl:flock() function to
fcntl::Flock::lock(). The new function returns a guard object, while
with the old function, the lock was associated directly with the file
descriptor.
It's good to stay up-to-date in general, but the impetus to do this now
is that in https://github.com/neondatabase/neon/pull/11929, I want to
use some functions that were added only in the latest version of 'nix',
and it's nice to not have to build multiple versions. (Although,
different versions of 'nix' are still pulled in as indirect dependencies
from other packages)
This PR adds a runtime validation mode to check adherence to alignment
and size-multiple requirements at the VirtualFile level.
This can help prevent alignment bugs from slipping into production
because test systems may have more lax requirements than production.
(This is not the case today, but it could change in the future).
It also allows catching O_DIRECT bugs on systems that don't have
O_DIRECT (macOS).
Consequently, we can now accept
`virtual_file_io_mode={direct,direct-rw}` on macOS now.
This has the side benefit of removing some annoying conditional
compilation around `IoMode`.
A third benefit is that it helped weed out size-multiple requirement
violation bugs in how the VirtualFile unit tests exercise read and write
APIs.
I seized the opportunity to trim these tests down to what actually
matters, i.e., exercising of the `OpenFiles` file descriptor cache.
Lastly, this PR flips the binary-built-in default to `DirectRw` so that
when running Python regress tests and benchmarks without specifying
`PAGESERVER_VIRTUAL_FILE_IO_MODE`, one gets the production behavior.
Refs
- fixes https://github.com/neondatabase/neon/issues/11676
# Improve OpenOptions API ergonomics
Closes#11787
This PR improves the OpenOptions API ergonomics by:
1. Making OpenOptions methods take and return owned Self instead of &mut
self
2. Changing VirtualFile::open_with_options_v2 to take an owned
OpenOptions
3. Removing unnecessary .clone() and .to_owned() calls
These changes make the API more idiomatic Rust by leveraging the builder
pattern with owned values, which is cleaner and more ergonomic than the
previous approach.
Link to Devin run:
https://app.devin.ai/sessions/c2a4b24f7aca40a3b3777f4259bf8ee1
Requested by: christian@neon.tech
---------
Co-authored-by: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>
Co-authored-by: christian@neon.tech <christian@neon.tech>
# Problem
The Pageserver read path exclusively uses direct IO if
`virtual_file_io_mode=direct`.
The write path is half-finished. Here is what the various writing
components use:
|what|buffering|flags on <br/>`v_f_io_mode`<br/>=`buffered`|flags on
<br/>`virtual_file_io_mode`<br/>=`direct`|
|-|-|-|-|
|`DeltaLayerWriter`| BlobWriter<BUFFERED=true> | () | () |
|`ImageLayerWriter`| BlobWriter<BUFFERED=false> | () | () |
|`download_layer_file`|BufferedWriter|()|()|
|`InMemoryLayer`|BufferedWriter|()|O_DIRECT|
The vehicle towards direct IO support is `BufferedWriter` which
- largely takes care of O_DIRECT alignment & size-multiple requirements
- double-buffering to mask latency
`DeltaLayerWriter`, `ImageLayerWriter` use `blob_io::BlobWriter` , which
has neither of these.
# Changes
## High-Level
At a high-level this PR makes the following primary changes:
- switch the two layer writer types to use `BufferedWriter` & make
sensitive to `virtual_file_io_mode` (via open_with_options_**v2**)
- make `download_layer_file` sensitive to `virtual_file_io_mode` (also
via open_with_options_**v2**)
- add `virtual_file_io_mode=direct-rw` as a feature gate
- we're hackish-ly piggybacking on OpenOptions's ask for write access
here
- this means with just `=direct` InMemoryLayer reads and writes no
longer uses O_DIRECT
- this is transitory and we'll remove the `direct-rw` variant once the
rollout is complete
(The `_v2` APIs for opening / creating VirtualFile are those that are
sensitive to `virtual_file_io_mode`)
The result is:
|what|uses <br/>`BufferedWriter`|flags on
<br/>`v_f_io_mode`<br/>=`buffered`|flags on
<br/>`v_f_io_mode`<br/>=`direct`|flags on
<br/>`v_f_io_mode`<br/>=`direct-rw`|
|-|-|-|-|-|
|`DeltaLayerWriter`| ~~Blob~~BufferedWriter | () | () | O_DIRECT |
|`ImageLayerWriter`| ~~Blob~~BufferedWriter | () | () | O_DIRECT |
|`download_layer_file`|BufferedWriter|()|()|O_DIRECT|
|`InMemoryLayer`|BufferedWriter|()|~~O_DIRECT~~()|O_DIRECT|
## Code-Level
The main change is:
- Switch `blob_io::BlobWriter` away from its own buffering method to use
`BufferedWriter`.
Additional prep for upholding `O_DIRECT` requirements:
- Layer writer `finish()` methods switched to use IoBufferMut for
guaranteed buffer address alignment. The size of the buffers is PAGE_SZ
and thereby implicitly assumed to fulfill O_DIRECT requirements.
For the hacky feature-gating via `=direct-rw`:
- Track `OpenOptions::write(true|false)` in a field; bunch of mechanical
churn.
- Consolidate the APIs in which we "open" or "create" VirtualFile for
better overview over which parts of the code use the `_v2` APIs.
Necessary refactorings & infra work:
- Add doc comments explaining how BufferedWriter ensures that writes are
compliant with O_DIRECT alignment & size constraints. This isn't new,
but should be spelled out.
- Add the concept of shutdown modes to `BufferedWriter::shutdown` to
make writer shutdown adhere to these constraints.
- The `PadThenTruncate` mode might not be necessary in practice because
I believe all layer files ever written are sized in multiples `PAGE_SZ`
and since `PAGE_SZ` is larger than the current alignment requirements
(512/4k depending on platform), it won't be necesary to pad.
- Some test (I believe `round_trip_test_compressed`?) required it though
- [ ] TODO: decide if we want to accept that complexity; if we do then
address TODO in the code to separate alignment requirement from buffer
capacity
- Add `set_len` (=`ftruncate`) VirtualFile operation to support the
above.
- Allow `BufferedWriter` to start at a non-zero offset (to make room for
the summary block).
Cleanups unlocked by this change:
- Remove non-positional APIs from VirtualFile (e.g. seek, write_full,
read_full)
Drive-by fixes:
- PR https://github.com/neondatabase/neon/pull/11585 aimed to run unit
tests for all `virtual_file_io_mode` combinations but didn't because of
a missing `_` in the env var.
# Performance
This section assesses this PR's impact on deployments with current
production setting (`=direct`) and anticipated impact of switching to
(`=direct-rw`).
For `DeltaLayerWriter`, `=direct` should remain unchanged to slightly
improved on throughput because the `BlobWriter`'s buffer had the same
size as the `BufferedWriter`'s buffer, but it didn't have the
double-buffering that `BufferedWriter` has.
The `=direct-rw` enables direct IO; throughput should not be suffering
because of double-buffering; benchmarks will show if this is true.
The `ImageLayerWriter` was previously not doing any buffering
(`BUFFERED=false`).
It went straight to issuing the IO operation to the underlying
VirtualFile and the buffering was done by the kernel.
The switch to `BufferedWriter` under `=direct` adds an additional memcpy
into the BufferedWriter's buffer.
We will win back that memcpy when enabling direct IO via `=direct-rw`.
A nice win from the switch to `BufferedWriter` is that ImageLayerWriter
performs >=16x fewer write operations to VirtualFile (the BlobWriter
performs one write per len field and one write per image value).
This should save low tens of microseconds of CPU overhead from doing all
these syscalls/io_uring operations, regardless of `=direct` or
`=direct-rw`.
Aside from problems with alignment, this write frequency without
double-buffering is prohibitive if we actually have to wait for the
disk, which is what will happen when we enable direct IO via
(`=direct-rw`).
Throughput should not be suffering because of BufferedWrite's
double-buffering; benchmarks will show if this is true.
`InMemoryLayer` at `=direct` will flip back to using buffered IO but
remain on BufferedWriter.
The buffered IO adds back one memcpy of CPU overhead.
Throughput should not suffer and will might improve on
not-memory-pressured Pageservers but let's remember that we're doing the
whole direct IO thing to eliminate global memory pressure as a source of
perf variability.
## bench_ingest
I reran `bench_ingest` on `im4gn.2xlarge` and `Hetzner AX102`.
Use `git diff` with `--word-diff` or similar to see the change.
General guidance on interpretation:
- immediate production impact of this PR without production config
change can be gauged by comparing the same `io_mode=Direct`
- end state of production switched over to `io_mode=DirectRw` can be
gauged by comparing old results' `io_mode=Direct` to new results'
`io_mode=DirectRw`
Given above guidance, on `im4gn.2xlarge`
- immediate impact is a significant improvement in all cases
- end state after switching has same significant improvements in all
cases
- ... except `ingest/io_mode=DirectRw volume_mib=128 key_size_bytes=8192
key_layout=Sequential write_delta=Yes` which only achieves `238 MiB/s`
instead of `253.43 MiB/s`
- this is a 6% degradation
- this workload is typical for image layer creation
# Refs
- epic https://github.com/neondatabase/neon/issues/9868
- stacked atop
- preliminary refactor https://github.com/neondatabase/neon/pull/11549
- bench_ingest overhaul https://github.com/neondatabase/neon/pull/11667
- derived from https://github.com/neondatabase/neon/pull/10063
Co-authored-by: Yuchen Liang <yuchen@neon.tech>
Main change:
- `BufferedWriter` owns the `W`; no more `Arc<W>`
- We introduce auto-delete-on-drop wrappers for `VirtualFile`.
- `TempVirtualFile` for write-only users
- `TempVirtualFileCoOwnedByEphemeralFileAndBufferedWriter` for
EphemeralFile which requires read access to the immutable prefix of the
file (see doc comments for details)
- Users of `BufferedWriter` hand it such a wrapped `VirtualFile`.
- The wrapped `VirtualFile` moves to the background flush task.
- On `BufferedWriter` shutdown, ownership moves back.
- Callers remove the wrapper (`disarm_into_inner()`) after doing final
touches, e.g., flushing index blocks and summary for delta/image layer
writers.
If the BufferedWriter isn't shut down properly via
`BufferedWriter::shutdown`, or if there is an error during final
touches, the wrapper type ensures that the file gets unlinked.
We store a GateGuard inside the wrapper to ensure that the Timeline is
still alive when unlinking on drop.
Rust doesn't have async drop yet, so, the unlinking happens using a
synchronous syscall.
NB we don't fsync the surrounding directory.
This is how it's been before this PR; I believe it is correct because
all of these files are temporary paths that get cleaned up on timeline
load.
Again, timeline load does not need to fsync because the next timeline
load will unlink again if the file reappears.
The auto-delete-on-drop can happen after a higher-level mechanism
retries.
Therefore, we switch all users to monotonically increasing, never-reused
temp file disambiguators.
The aspects pointed out in the last two paragraphs will receive further
cleanup in follow-up task
- https://github.com/neondatabase/neon/issues/11692
Drive-by changes:
- It turns out we can remove the two-pronged code in the layer file
download code.
No need to make this a separate PR because all of production already
uses `tokio-epoll-uring` with the buffered writer for many weeks.
Refs
- epic https://github.com/neondatabase/neon/issues/9868
- alternative to https://github.com/neondatabase/neon/pull/11544
# Problem
If the Pageserver ingest path
(InMemoryLayer=>EphemeralFile=>BufferedWriter)
encounters ENOSPC or any other write IO error when flushing the mutable
buffer
of the BufferedWriter, the buffered writer is left in a state where
subsequent _reads_
from the InMemoryLayer it will cause a `must not use after we returned
an error` panic.
The reason is that
1. the flush background task bails on flush failure,
2. causing the `FlushHandle::flush` function to fail at channel.recv()
and
3. causing the `FlushHandle::flush` function to bail with the flush
error,
4. leaving its caller `BufferedWriter::flush` with
`BufferedWriter::mutable = None`,
5. once the InMemoryLayer's RwLock::write guard is dropped, subsequent
reads can enter,
6. those reads find `mutable = None` and cause the panic.
# Context
It has always been the contract that writes against the BufferedWriter
API
must not be retried because the writer/stream-style/append-only
interface makes no atomicity guarantees ("On error, did nothing or a
piece of the buffer get appended?").
The idea was that the error would bubble up to upper layers that can
throw away the buffered writer and create a new one. (See our [internal
error handling policy document on how to handle e.g.
`ENOSPC`](c870a50bc0/src/storage/handling_io_and_logical_errors.md (L36-L43))).
That _might_ be true for delta/image layer writers, I haven't checked.
But it's certainly not true for the ingest path: there are no provisions
to throw away an InMemoryLayer that encountered a write error an
reingest the WAL already written to it.
Adding such higher-level retries would involve either resetting
last_record_lsn to a lower value and restarting walreceiver. The code
isn't flexible enough to do that, and such complexity likely isn't worth
it given that write errors are rare.
# Solution
The solution in this PR is to retry _any_ failing write operation
_indefinitely_ inside the buffered writer flush task, except of course
those that are fatal as per `maybe_fatal_err`.
Retrying indefinitely ensures that `BufferedWriter::mutable` is never
left `None` in the case of IO errors, thereby solving the problem
described above.
It's a clear improvement over the status quo.
However, while we're retrying, we build up backpressure because the
`flush` is only double-buffered, not infinitely buffered.
Backpressure here is generally good to avoid resource exhaustion, **but
blocks reads** and hence stalls GetPage requests because InMemoryLayer
reads and writes are mutually exclusive.
That's orthogonal to the problem that is solved here, though.
## Caveats
Note that there are some remaining conditions in the flush background
task where it can bail with an error. I have annotated one of them with
a TODO comment.
Hence the `FlushHandle::flush` is still fallible and hence the overall
scenario of leaving `mutable = None` on the bail path is still possible.
We can clean that up in a later commit.
Note also that retrying indefinitely is great for temporary errors like
ENOSPC but likely undesirable in case the `std::io::Error` we get is
really due to higher-level logic bugs.
For example, we could fail to flush because the timeline or tenant
directory got deleted and VirtualFile's reopen fails with ENOENT.
Note finally that cancellation is not respected while we're retrying.
This means we will block timeline/tenant/pageserver shutdown.
The reason is that the existing cancellation story for the buffered
writer background task was to recv from flush op channel until the
sending side (FlushHandle) is explicitly shut down or dropped.
Failing to handle cancellation carries the operational risk that even if
a single timeline gets stuck because of a logic bug such as the one laid
out above, we must still restart the whole pageserver process.
# Alternatives Considered
As pointed out in the `Context` section, throwing away a InMemoryLayer
that encountered an error and reingesting the WAL is a lot of complexity
that IMO isn't justified for such an edge case.
Also, it's wasteful.
I think it's a local optimum.
A more general and simpler solution for ENOSPC is to `abort()` the
process and run eviction on startup before bringing up the rest of
pageserver.
I argued for it in the past, the pro arguments are still valid and
complete:
https://neondb.slack.com/archives/C033RQ5SPDH/p1716896265296329
The trouble at the time was implementing eviction on startup.
However, maybe things are simpler now that we are fully storcon-managed
and all tenants have secondaries.
For example, if pageserver `abort()`s on ENOSPC and then simply don't
respond to storcon heartbeats while we're running eviction on startup,
storcon will fail tenants over to the secondary anyway, giving us all
the time we need to clean up.
The downside is that if there's a systemic space management bug, above
proposal will just propagate the problem to other nodes. But I imagine
that because of the delays involved with filling up disks, the system
might reach a half-stable state, providing operators more time to react.
# Demo
Intermediary commit `a03f335121480afc0171b0f34606bdf929e962c5` is demoed
in this (internal) screen recording:
https://drive.google.com/file/d/1nBC6lFV2himQ8vRXDXrY30yfWmI2JL5J/view?usp=drive_link
# Perf Testing
Ran `bench_ingest` on tmpfs, no measurable difference.
Spans are uniquely owned by the flush task, and the span stack isn't too
deep, so, enter and exit should be cheap.
Plus, each flush takes ~150us with direct IO enabled, so, not _that_
high frequency event anyways.
# Refs
- fixes https://github.com/neondatabase/neon/issues/10856
# Refs
- fixes https://github.com/neondatabase/neon/issues/6107
# Problem
`VirtualFile` currently parses the path it is opened with to identify
the `tenant,shard,timeline` labels to be used for the `STORAGE_IO_SIZE`
metric.
Further, for each read or write call to VirtualFile, it uses
`with_label_values` to retrieve the correct metrics object, which under
the hood is a global hashmap guarded by a parking_lot mutex.
We perform tens of thousands of reads and writes per second on every
pageserver instance; thus, doing the mutex lock + hashmap lookup is
wasteful.
# Changes
Apply the technique we use for all other timeline-scoped metrics to
avoid the repeat `with_label_values`: add it to `TimelineMetrics`.
Wrap `TimelineMetrics` into an `Arc`.
Propagate the `Arc<TimelineMetrics>` down do `VirtualFile`, and use
`Timeline::metrics::storage_io_size`.
To avoid contention on the `Arc<TimelineMetrics>`'s refcount atomics
between different connection handlers for the same timeline, we wrap it
into another Arc.
To avoid frequent allocations, we store that Arc<Arc<TimelineMetrics>>
inside the per-connection timeline cache.
Preliminary refactorings to enable this change:
- https://github.com/neondatabase/neon/pull/11001
- https://github.com/neondatabase/neon/pull/11030
# Performance
I ran the benchmarks in
`test_runner/performance/pageserver/pagebench/test_pageserver_max_throughput_getpage_at_latest_lsn.py`
on an `i3en.3xlarge` because that's what we currently run them on.
None of the benchmarks shows a meaningful difference in latency or
throughput or CPU utilization.
I would have expected some improvement in the
many-tenants-one-client-each workload because they all hit that hashmap
constantly, and clone the same `UintCounter` / `Arc` inside of it.
But apparently the overhead is miniscule compared to the remaining work
we do per getpage.
Yet, since the changes are already made, the added complexity is
manageable, and the perf overhead of `with_label_values` demonstrable in
micro-benchmarks, let's have this change anyway.
Also, propagating TimelineMetrics through RequestContext might come in
handy down the line.
The micro-benchmark that demonstrates perf impact of
`with_label_values`, along with other pitfalls and mitigation techniques
around the `metrics`/`prometheus` crate:
- https://github.com/neondatabase/neon/pull/11019
# Alternative Designs
An earlier iteration of this PR stored an `Arc<Arc<Timeline>>` inside
`RequestContext`.
The problem is that this risks reference cycles if the RequestContext
gets stored in an object that is owned directly or indirectly by
`Timeline`.
Ideally, we wouldn't be using this mess of Arc's at all and propagate
Rust references instead.
But tokio requires tasks to be `'static`, and so, we wouldn't be able to
propagate references across task boundaries, which is incompatible with
any sort of fan-out code we already have (e.g. concurrent IO) or future
code (parallel compaction).
So, opt for Arc for now.
Updates storage components to edition 2024. We like to stay on the
latest edition if possible. There is no functional changes, however some
code changes had to be done to accommodate the edition's breaking
changes.
The PR has two commits:
* the first commit updates storage crates to edition 2024 and appeases
`cargo clippy` by changing code. i have accidentially ran the formatter
on some files that had other edits.
* the second commit performs a `cargo fmt`
I would recommend a closer review of the first commit and a less close
review of the second one (as it just runs `cargo fmt`).
part of https://github.com/neondatabase/neon/issues/10918
Before this PR, an IO error returned from the kernel, e.g., due to a bad
disk, would get bubbled up, all the way to a user-visible query failing.
This is against the IO error handling policy where we have established
and is hence being rectified in this PR.
[[(internal Policy document
link)]](bef44149f7/src/storage/handling_io_and_logical_errors.md (L33-L35))
The practice on the write path seems to be that we call
`maybe_fatal_err()` or `fatal_err()` fairly high up the stack.
That is, regardless of whether std::fs, tokio::fs, or VirtualFile is
used to perform the IO.
For the read path, I choose a centralized approach in this PR by
checking for errors as close to the kernel interface as possible.
I believe this is better for long-term consistency.
To mitigate the problem of missing context if we abort so far down in
the stack, the `on_fatal_io_error` now captures and logs a backtrace.
I grepped the pageserver code base for `fs::read` to convince myself
that all non-VirtualFile reads already handle IO errors according to
policy.
Refs
- fixes https://github.com/neondatabase/neon/issues/10454
Related to #10308, we might have legitimate changes in file size or
generation. Those changes should not cause warn log lines.
In order to detect changes of the generation number while the file size
stayed the same, load the metadata that we store on disk on loading of
the timeline.
Still do a comparison with the on-disk layer sizes to find any
discrepancies that might occur due to race conditions (new metadata file
gets written but layer file has not been updated yet, and PS shuts
down). However, as it's possible to hit it in a race conditon, downgrade
it to a warning.
Also fix a mistake in #10529: we want to compare the old with the new
metadata, not the old metadata with itself.
Closes#9387.
## Problem
`BufferedWriter` cannot proceed while the owned buffer is flushing to
disk. We want to implement double buffering so that the flush can happen
in the background. See #9387.
## Summary of changes
- Maintain two owned buffers in `BufferedWriter`.
- The writer is in charge of copying the data into owned, aligned
buffer, once full, submit it to the flush task.
- The flush background task is in charge of flushing the owned buffer to
disk, and returned the buffer to the writer for reuse.
- The writer and the flush background task communicate through a
bi-directional channel.
For in-memory layer, we also need to be able to read from the buffered
writer in `get_values_reconstruct_data`. To handle this case, we did the
following
- Use replace `VirtualFile::write_all` with `VirtualFile::write_all_at`,
and use `Arc` to share it between writer and background task.
- leverage `IoBufferMut::freeze` to get a cheaply clonable `IoBuffer`,
one clone will be submitted to the channel, the other clone will be
saved within the writer to serve reads. When we want to reuse the
buffer, we can invoke `IoBuffer::into_mut`, which gives us back the
mutable aligned buffer.
- InMemoryLayer reads is now aware of the maybe_flushed part of the
buffer.
**Caveat**
- We removed the owned version of write, because this interface does not
work well with buffer alignment. The result is that without direct IO
enabled,
[`download_object`](a439d57050/pageserver/src/tenant/remote_timeline_client/download.rs (L243))
does one more memcpy than before this PR due to the switch to use
`_borrowed` version of the write.
- "Bypass aligned part of write" could be implemented later to avoid
large amount of memcpy.
**Testing**
- use an oneshot channel based control mechanism to make flush behavior
deterministic in test.
- test reading from `EphemeralFile` when the last submitted buffer is
not flushed, in-progress, and done flushing to disk.
## Performance
We see performance improvement for small values, and regression on big
values, likely due to being CPU bound + disk write latency.
[Results](https://www.notion.so/neondatabase/Benchmarking-New-BufferedWriter-11-20-2024-143f189e0047805ba99acda89f984d51?pvs=4)
## Checklist before requesting a review
- [ ] I have performed a self-review of my code.
- [ ] If it is a core feature, I have added thorough tests.
- [ ] Do we need to implement analytics? if so did you add the relevant
metrics to the dashboard?
- [ ] If this PR requires public announcement, mark it with
/release-notes label and add several sentences in this section.
## Checklist before merging
- [ ] Do not forget to reformat commit message to not include the above
checklist
---------
Signed-off-by: Yuchen Liang <yuchen@neon.tech>
Co-authored-by: Christian Schwarz <christian@neon.tech>
## Problem
`no_sync` initially just skipped syncfs on startup (#9677). I'm also
interested in flaky tests that time out during pageserver shutdown while
flushing l0s, so to eliminate disk throughput as a source of issues
there,
## Summary of changes
- Drive-by change for test timeouts: add a couple more ::info logs
during pageserver startup so it's obvious which part got stuck.
- Add a SyncMode enum to configure VirtualFile and respect it in
sync_all and sync_data functions
- During pageserver startup, set SyncMode according to `no_sync`
Part of #8130
## Problem
Pageserver previously goes through the kernel page cache for all the
IOs. The kernel page cache makes light-loaded pageserver have deceptive
fast performance. Using direct IO would offer predictable latencies of
our virtual file IO operations.
In particular for reads, the data pages also have an extremely low
temporal locality because the most frequently accessed pages are cached
on the compute side.
## Summary of changes
This PR enables pageserver to use direct IO for delta layer and image
layer reads. We can ship them separately because these layers are
write-once, read-many, so we will not be mixing buffered IO with direct
IO.
- implement `IoBufferMut`, an buffer type with aligned allocation
(currently set to 512).
- use `IoBufferMut` at all places we are doing reads on image + delta
layers.
- leverage Rust type system and use `IoBufAlignedMut` marker trait to
guarantee that the input buffers for the IO operations are aligned.
- page cache allocation is also made aligned.
_* in-memory layer reads and the write path will be shipped separately._
## Testing
Integration test suite run with O_DIRECT enabled:
https://github.com/neondatabase/neon/pull/9350
## Performance
We evaluated performance based on the `get-page-at-latest-lsn`
benchmark. The results demonstrate a decrease in the number of IOps, no
sigificant change in the latency mean, and an slight improvement on the
p99.9 and p99.99 latencies.
[Benchmark](https://www.notion.so/neondatabase/Benchmark-O_DIRECT-for-image-and-delta-layers-2024-10-01-112f189e00478092a195ea5a0137e706?pvs=4)
## Rollout
We will add `virtual_file_io_mode=direct` region by region to enable
direct IO on image + delta layers.
Signed-off-by: Yuchen Liang <yuchen@neon.tech>
## Problem
We need a way to incrementally switch to direct IO. During the rollout
we might want to switch to O_DIRECT on image and delta layer read path
first before others.
## Summary of changes
- Revisited and simplified direct io config in `PageserverConf`.
- We could add a fallback mode for open, but for read there isn't a
reasonable alternative (without creating another buffered virtual file).
- Added a wrapper around `VirtualFile`, current implementation become
`VirtualFileInner`
- Use `open_v2`, `create_v2`, `open_with_options_v2` when we want to use
the IO mode specified in PS config.
- Once we onboard all IO through VirtualFile using this new API, we will
delete the old code path.
- Make io mode live configurable for benchmarking.
- Only guaranteed for files opened after the config change, so do it
before the experiment.
As an example, we are using `open_v2` with
`virtual_file::IoMode::Direct` in
https://github.com/neondatabase/neon/pull/9169
We also remove `io_buffer_alignment` config in
a04cfd754b and use it as a compile time
constant. This way we don't have to carry the alignment around or make
frequent call to retrieve this information from the static variable.
Signed-off-by: Yuchen Liang <yuchen@neon.tech>
close https://github.com/neondatabase/neon/issues/8140
The original issue is rather vague on what we should do. After
discussion w/ @problame we decided to narrow down the problems we want
to solve in that issue.
* read path -- do not panic for now.
* write path -- panic only on write errors (i.e., device error, fsync
error), but not on no-space for now.
The guideline is that if the pageserver behavior could lead to violation
of persistent constraints (i.e., return an operation as successful but
not actually persisting things), we should panic. Fsync is the place
where both of us agree that we should panic, because if fsync fails, the
kernel will mark dirty pages as clean, and the next fsync will not
necessarily return false. This would make the storage client assume the
operation is successful.
## Summary of changes
Make fsync panic on fatal errors.
---------
Signed-off-by: Alex Chi Z <chi@neon.tech>
Part of #8130
## Problem
After deploying https://github.com/neondatabase/infra/pull/1927, we
shipped `io_buffer_alignment=512` to all prod region. The
`AdjacentVectoredReadBuilder` code path is no longer taken and we are
running pageserver unit tests 6 times in the CI. Removing it would
reduce the test duration by 30-60s.
## Summary of changes
- Remove `AdjacentVectoredReadBuilder` code.
- Bump the minimum `io_buffer_alignment` requirement to at least 512
bytes.
- Use default `io_buffer_alignment` for Rust unit tests.
Signed-off-by: Yuchen Liang <yuchen@neon.tech>
Addresses the 1.82 beta clippy lint `too_long_first_doc_paragraph` by
adding newlines to the first sentence if it is short enough, and making
a short first sentence if there is the need.
This PR simplifies the pageserver configuration parsing as follows:
* introduce the `pageserver_api::config::ConfigToml` type
* implement `Default` for `ConfigToml`
* use serde derive to do the brain-dead leg-work of processing the toml
document
* use `serde(default)` to fill in default values
* in `pageserver` crate:
* use `toml_edit` to deserialize the pageserver.toml string into a
`ConfigToml`
* `PageServerConfig::parse_and_validate` then
* consumes the `ConfigToml`
* destructures it exhaustively into its constituent fields
* constructs the `PageServerConfig`
The rules are:
* in `ConfigToml`, use `deny_unknown_fields` everywhere
* static default values go in `pageserver_api`
* if there cannot be a static default value (e.g. which default IO
engine to use, because it depends on the runtime), make the field in
`ConfigToml` an `Option`
* if runtime-augmentation of a value is needed, do that in
`parse_and_validate`
* a good example is `virtual_file_io_engine` or `l0_flush`, both of
which need to execute code to determine the effective value in
`PageServerConf`
The benefits:
* massive amount of brain-dead repetitive code can be deleted
* "unused variable" compile-time errors when removing a config value,
due to the exhaustive destructuring in `parse_and_validate`
* compile-time errors guide you when adding a new config field
Drawbacks:
* serde derive is sometimes a bit too magical
* `deny_unknown_fields` is easy to miss
Future Work / Benefits:
* make `neon_local` use `pageserver_api` to construct `ConfigToml` and
write it to `pageserver.toml`
* This provides more type safety / coompile-time errors than the current
approach.
### Refs
Fixes#3682
### Future Work
* `remote_storage` deser doesn't reject unknown fields
https://github.com/neondatabase/neon/issues/8915
* clean up `libs/pageserver_api/src/config.rs` further
* break up into multiple files, at least for tenant config
* move `models` as appropriate / refine distinction between config and
API models / be explicit about when it's the same
* use `pub(crate)` visibility on `mod defaults` to detect stale values
## Summary of changes
- Setting default io_buffer_alignment to 512 bytes.
- Fix places that assumed `DEFAULT_IO_BUFFER_ALIGNMENT=0`
- Adapt unit tests to handle merge with `chunk size <= 4096`.
## Testing and Performance
We have done sufficient performance de-risking.
Enabling it by default completes our correctness de-risking before the
next release.
Context: https://neondb.slack.com/archives/C07BZ38E6SD/p1725026845455259
Signed-off-by: Yuchen Liang <yuchen@neon.tech>
Co-authored-by: Christian Schwarz <christian@neon.tech>
Part of #8130, closes#8719.
## Problem
Currently, vectored blob io only coalesce blocks if they are immediately
adjacent to each other. When we switch to Direct IO, we need a way to
coalesce blobs that are within the dio-aligned boundary but has gap
between them.
## Summary of changes
- Introduces a `VectoredReadCoalesceMode` for `VectoredReadPlanner` and
`StreamingVectoredReadPlanner` which has two modes:
- `AdjacentOnly` (current implementation)
- `Chunked(<alignment requirement>)`
- New `ChunkedVectorBuilder` that considers batching `dio-align`-sized
read, the start and end of the vectored read will respect
`stx_dio_offset_align` / `stx_dio_mem_align` (`vectored_read.start` and
`vectored_read.blobs_at.first().start_offset` will be two different
value).
- Since we break the assumption that blobs within single `VectoredRead`
are next to each other (implicit end offset), we start to store blob end
offsets in the `VectoredRead`.
- Adapted existing tests to run in both `VectoredReadCoalesceMode`.
- The io alignment can also be live configured at runtime.
Signed-off-by: Yuchen Liang <yuchen@neon.tech>
The `tokio_epoll_uring::Slice` / `tokio_uring::Slice` type is weird.
The new `FullSlice` newtype is better. See the doc comment for details.
The naming is not ideal, but we'll clean that up in a future refactoring
where we move the `FullSlice` into `tokio_epoll_uring`. Then, we'll do
the following:
* tokio_epoll_uring::Slice is removed
* `FullSlice` becomes `tokio_epoll_uring::IoBufView`
* new type `tokio_epoll_uring::IoBufMutView` for the current
`tokio_epoll_uring::Slice<IoBufMut>`
Context
-------
I did this work in preparation for
https://github.com/neondatabase/neon/pull/8537.
There, I'm changing the type that the `inmemory_layer.rs` passes to
`DeltaLayerWriter::put_value_bytes` and thus it seemed like a good
opportunity to make this cleanup first.
## Problem
Some developers build on MacOS, which doesn't have io_uring.
## Summary of changes
- Add `io_engine_for_bench`, which on linux will give io_uring or panic
if it's unavailable, and on MacOS will always panic.
We do not want to run such benchmarks with StdFs: the results aren't
interesting, and will actively waste the time of any developers who
start investigating performance before they realize they're using a
known-slow I/O backend.
Why not just conditionally compile this benchmark on linux only? Because
even on linux, I still want it to refuse to run if it can't get
io_uring.
Part of #8130, [RFC: Direct IO For Pageserver](https://github.com/neondatabase/neon/blob/problame/direct-io-rfc/docs/rfcs/034-direct-io-for-pageserver.md)
## Description
Add pageserver config for evaluating/enabling direct I/O.
- Disabled: current default, uses buffered io as is.
- Evaluate: still uses buffered io, but could do alignment checking and
perf simulation (pad latency by direct io RW to a fake file).
- Enabled: uses direct io, behavior on alignment error is configurable.
Signed-off-by: Yuchen Liang <yuchen@neon.tech>
part of https://github.com/neondatabase/neon/issues/7418
I reviewed how the VirtualFile API's `read` methods look like and came
to the conclusion that we've been using `IoBufMut` / `BoundedBufMut` /
`Slice` wrong.
This patch rectifies the situation.
# Change 1: take `tokio_epoll_uring::Slice` in the read APIs
Before, we took an `IoBufMut`, which is too low of a primitive and while
it _seems_ convenient to be able to pass in a `Vec<u8>` without any
fuzz, it's actually very unclear at the callsite that we're going to
fill up that `Vec` up to its `capacity()`, because that's what
`IoBuf::bytes_total()` returns and that's what
`VirtualFile::read_exact_at` fills.
By passing a `Slice` instead, a caller that "just wants to read into a
`Vec`" is forced to be explicit about it, adding either `slice_full()`
or `slice(x..y)`, and these methods panic if the read is outside of the
bounds of the `Vec::capacity()`.
Last, passing slices is more similar to what the `std::io` APIs look
like.
# Change 2: fix UB in `virtual_file_io_engine=std-fs`
While reviewing call sites, I noticed that the
`io_engine::IoEngine::read_at` method for `StdFs` mode has been
constructing an `&mut[u8]` from raw parts that were uninitialized.
We then used `std::fs::File::read_exact` to initialize that memory, but,
IIUC we must not even be constructing an `&mut[u8]` where some of the
memory isn't initialized.
So, stop doing that and add a helper ext trait on `Slice` to do the
zero-initialization.
# Change 3: eliminate `read_exact_at_n`
The `read_exact_at_n` doesn't make sense because the caller can just
1. `slice = buf.slice()` the exact memory it wants to fill
2. `slice = read_exact_at(slice)`
3. `buf = slice.into_inner()`
Again, the `std::io` APIs specify the length of the read via the Rust
slice length.
We should do the same for the owned buffers IO APIs, i.e., via
`Slice::bytes_total()`.
# Change 4: simplify filling of `PageWriteGuard`
The `PageWriteGuardBuf::init_up_to` was never necessary.
Remove it. See changes to doc comment for more details.
---
Reviewers should probably look at the added test case first, it
illustrates my case a bit.
## Problem
#7371
## Summary of changes
* The VirtualFile::open, open_with_options, and create methods use
AsRef, similar to the standard library's std::fs APIs.
part of https://github.com/neondatabase/neon/issues/7124
Changes
-------
This PR replaces the `EphemeralFile::write_blob`-specifc `struct Writer`
with re-use of `owned_buffers_io::write::BufferedWriter`.
Further, it restructures the code to cleanly separate
* the high-level aspect of EphemeralFile's write_blob / read_blk API
* the page-caching aspect
* the aspect of IO
* performing buffered write IO to an underlying VirtualFile
* serving reads from either the VirtualFile or the buffer if it hasn't
been flushed yet
* the annoying "feature" that reads past the end of the written range
are allowed and expected to return zeroed memory, as long as one remains
within one PAGE_SZ
# Problem
On-demand downloads are still using `tokio::fs`, which we know is
inefficient.
# Changes
- Add `pagebench ondemand-download-churn` to quantify on-demand download
throughput
- Requires dumping layer map, which required making `history_buffer`
impl `Deserialize`
- Implement an equivalent of `tokio::io::copy_buf` for owned buffers =>
`owned_buffers_io` module and children.
- Make layer file download sensitive to `io_engine::get()`, using
VirtualFile + above copy loop
- For this, I had to move some code into the `retry_download`, e.g.,
`sync_all()` call.
Drive-by:
- fix missing escaping in `scripts/ps_ec2_setup_instance_store`
- if we failed in retry_download to create a file, we'd try to remove
it, encounter `NotFound`, and `abort()` the process using
`on_fatal_io_error`. This PR adds treats `NotFound` as a success.
# Testing
Functional
- The copy loop is generic & unit tested.
Performance
- Used the `ondemand-download-churn` benchmark to manually test against
real S3.
- Results (public Notion page):
https://neondatabase.notion.site/Benchmarking-tokio-epoll-uring-on-demand-downloads-2024-04-15-newer-code-03c0fdc475c54492b44d9627b6e4e710?pvs=4
- Performance is equivalent at low concurrency. Jumpier situation at
high concurrency, but, still less CPU / throughput with
tokio-epoll-uring.
- It’s a win.
# Future Work
Turn the manual performance testing described in the above results
document into a performance regression test:
https://github.com/neondatabase/neon/issues/7146
fixes https://github.com/neondatabase/neon/issues/7116
Changes:
- refactor PageServerConfigBuilder: support not-set values
- implement runtime feature test
- use runtime feature test to determine `virtual_file_io_engine` if not
explicitly configured in the config
- log the effective engine at startup
- drive-by: improve assertion messages in `test_pageserver_init_node_id`
This needed a tiny bit of tokio-epoll-uring work, hence bumping it.
Changelog:
```
git log --no-decorate --oneline --reverse 868d2c42b5d54ca82fead6e8f2f233b69a540d3e..342ddd197a060a8354e8f11f4d12994419fff939
c7a74c6 Bump mio from 0.8.8 to 0.8.11
4df3466 Bump mio from 0.8.8 to 0.8.11 (#47)
342ddd1 lifecycle: expose `LaunchResult` enum (#49)
```
part of #6663
See that epic for more context & related commits.
Problem
-------
Before this PR, the layer-file-creating code paths were using
VirtualFile, but under the hood these were still blocking system calls.
Generally this meant we'd stall the executor thread, unless the caller
"knew" and used the following pattern instead:
```
spawn_blocking(|| {
Handle::block_on(async {
VirtualFile::....().await;
})
}).await
```
Solution
--------
This PR adopts `tokio-epoll-uring` on the layer-file-creating code paths
in pageserver.
Note that on-demand downloads still use `tokio::fs`, these will be
converted in a future PR.
Design: Avoiding Regressions With `std-fs`
------------------------------------------
If we make the VirtualFile write path truly async using
`tokio-epoll-uring`, should we then remove the `spawn_blocking` +
`Handle::block_on` usage upstack in the same commit?
No, because if we’re still using the `std-fs` io engine, we’d then block
the executor in those places where previously we were protecting us from
that through the `spawn_blocking` .
So, if we want to see benefits from `tokio-epoll-uring` on the write
path while also preserving the ability to switch between
`tokio-epoll-uring` and `std-fs` , where `std-fs` will behave identical
to what we have now, we need to ***conditionally* use `spawn_blocking +
Handle::block_on`** .
I.e., in the places where we use that know, we’ll need to make that
conditional based on the currently configured io engine.
It boils down to investigating all the places where we do
`spawn_blocking(... block_on(... VirtualFile::...))`.
Detailed [write-up of that investigation in
Notion](https://neondatabase.notion.site/Surveying-VirtualFile-write-path-usage-wrt-tokio-epoll-uring-integration-spawn_blocking-Handle-bl-5dc2270dbb764db7b2e60803f375e015?pvs=4
), made publicly accessible.
tl;dr: Preceding PRs addressed the relevant call sites:
- `metadata` file: turns out we could simply remove it (#6777, #6769,
#6775)
- `create_delta_layer()`: made sensitive to `virtual_file_io_engine` in
#6986
NB: once we are switched over to `tokio-epoll-uring` everywhere in
production, we can deprecate `std-fs`; to keep macOS support, we can use
`tokio::fs` instead. That will remove this whole headache.
Code Changes In This PR
-----------------------
- VirtualFile API changes
- `VirtualFile::write_at`
- implement an `ioengine` operation and switch `VirtualFile::write_at`
to it
- `VirtualFile::metadata()`
- curiously, we only use it from the layer writers' `finish()` methods
- introduce a wrapper `Metadata` enum because `std::fs::Metadata` cannot
be constructed by code outside rust std
- `VirtualFile::sync_all()` and for completeness sake, add
`VirtualFile::sync_data()`
Testing & Rollout
-----------------
Before merging this PR, we ran the CI with both io engines.
Additionally, the changes will soak in staging.
We could have a feature gate / add a new io engine
`tokio-epoll-uring-write-path` to do a gradual rollout. However, that's
not part of this PR.
Future Work
-----------
There's still some use of `std::fs` and/or `tokio::fs` for directory
namespace operations, e.g. `std::fs::rename`.
We're not addressing those in this PR, as we'll need to add the support
in tokio-epoll-uring first. Note that rename itself is usually fast if
the directory is in the kernel dentry cache, and only the fsync after
rename is slow. These fsyncs are using tokio-epoll-uring, so, the impact
should be small.
## Problem
The vectored read path proposed in
https://github.com/neondatabase/neon/pull/6576 seems
to be functionally correct, but in my testing (see below) it is about 10-20% slower than the naive
sequential vectored implementation.
## Summary of changes
There's three parts to this PR:
1. Supporting vectored blob reads. This is actually trickier than it
sounds because on disk blobs are prefixed with a variable length size header.
Since the blobs are not necessarily fixed size, we need to juggle the offsets
such that the callers can retrieve the blobs from the resulting buffer.
2. Merge disk read requests issued by the vectored read path up to a
maximum size. Again, the merging is complicated by the fact that blobs
are not fixed size. We keep track of the begin and end offset of each blob
and pass them into the vectored blob reader. In turn, the reader will return
a buffer and the offsets at which the blobs begin and end.
3. A benchmark for basebackup requests against tenant with large SLRU
block counts is added. This required a small change to pagebench and a new config
variable for the pageserver which toggles the vectored get validation.
We can probably optimise things further by adding a little bit of
concurrency for our IO. In principle, it's as simple as spawning a task which deals with issuing
IO and doing the serialisation and handling on the parent task which receives input via a
channel.
Reverts neondatabase/neon#6765 , bringing back #6731
We concluded that #6731 never was the root cause for the instability in
staging.
More details:
https://neondb.slack.com/archives/C033RQ5SPDH/p1708011674755319
However, the massive amount of concurrent `spawn_blocking` calls from
the `save_metadata` calls during startups might cause a performance
regression.
So, we'll merge this PR here after we've stopped writing the metadata
#6769).
context: https://github.com/neondatabase/neon/issues/6663
Building atop #6664, this PR switches `write_all_at` to take owned
buffers.
The main challenge here is the `EphemeralFile::mutable_tail`, for which
I'm picking the ugly solution of an `Option` that is `None` while the IO
is in flight.
After this, we will be able to switch `write_at` to take owned buffers
and call tokio-epoll-uring's `write` function with that owned buffer.
That'll be done in #6378.
Some callers of `VirtualFile::crashsafe_overwrite` call it on the
executor thread, thereby potentially stalling it.
Others are more diligent and wrap it in `spawn_blocking(...,
Handle::block_on, ... )` to avoid stalling the executor thread.
However, because `crashsafe_overwrite` uses
VirtualFile::open_with_options internally, we spawn a new thread-local
`tokio-epoll-uring::System` in the blocking pool thread that's used for
the `spawn_blocking` call.
This PR refactors the situation such that we do the `spawn_blocking`
inside `VirtualFile::crashsafe_overwrite`. This unifies the situation
for the better:
1. Callers who didn't wrap in `spawn_blocking(..., Handle::block_on,
...)` before no longer stall the executor.
2. Callers who did it before now can avoid the `block_on`, resolving the
problem with the short-lived `tokio-epoll-uring::System`s in the
blocking pool threads.
A future PR will build on top of this and divert to tokio-epoll-uring if
it's configures as the IO engine.
Changes
-------
- Convert implementation to std::fs and move it into `crashsafe.rs`
- Yes, I know, Safekeepers (cc @arssher ) added `durable_rename` and
`fsync_async_opt` recently. However, `crashsafe_overwrite` is different
in the sense that it's higher level, i.e., it's more like
`std::fs::write` and the Safekeeper team's code is more building block
style.
- The consequence is that we don't use the VirtualFile file descriptor
cache anymore.
- I don't think it's a big deal because we have plenty of slack wrt
production file descriptor limit rlimit (see [this
dashboard](https://neonprod.grafana.net/d/e4a40325-9acf-4aa0-8fd9-f6322b3f30bd/pageserver-open-file-descriptors?orgId=1))
- Use `tokio::task::spawn_blocking` in
`VirtualFile::crashsafe_overwrite` to call the new
`crashsafe::overwrite` API.
- Inspect all callers to remove any double-`spawn_blocking`
- spawn_blocking requires the captures data to be 'static + Send. So,
refactor the callers. We'll need this for future tokio-epoll-uring
support anyway, because tokio-epoll-uring requires owned buffers.
Related Issues
--------------
- overall epic to enable write path to tokio-epoll-uring: #6663
- this is also kind of relevant to the tokio-epoll-uring System creation
failures that we encountered in staging, investigation being tracked in
#6667
- why is it relevant? Because this PR removes two uses of
`spawn_blocking+Handle::block_on`
This PR adds an API to live-reconfigure the VirtualFile io engine.
It also adds a flag to `pagebench get-page-latest-lsn`, which is where I
found this functionality to be useful: it helps compare the io engines
in a benchmark without re-compiling a release build, which took ~50s on
the i3en.3xlarge where I was doing the benchmark.
Switching the IO engine is completely safe at runtime.
## Problem
Spun off from https://github.com/neondatabase/neon/pull/6394 -- this PR
is just the persistence parts and the changes that enable it to work
nicely
## Summary of changes
- Revert #6444 and #6450
- In neon_local, start a vanilla postgres instance for the attachment
service to use.
- Adopt `diesel` crate for database access in attachment service. This
uses raw SQL migrations as the source of truth for the schema, so it's a
soft dependency: we can switch libraries pretty easily.
- Rewrite persistence.rs to use postgres (via diesel) instead of JSON.
- Preserve JSON read+write at startup and shutdown: this enables using
the JSON format in compatibility tests, so that we don't have to commit
to our DB schema yet.
- In neon_local, run database creation + migrations before starting
attachment service
- Run the initial reconciliation in Service::spawn in the background, so
that the pageserver + attachment service don't get stuck waiting for
each other to start, when restarting both together in a test.
The pagebench integration PR (#6214) is the first to SIGQUIT & then
restart attachment_service.
With many tenants (100), we have found frequent failures on restart in
the CI[^1].
[^1]:
[Allure](https://neon-github-public-dev.s3.amazonaws.com/reports/pr-6214/7615750160/index.html#suites/e26265675583c610f99af77084ae58f1/851ff709578c4452/)
```
2024-01-22T19:07:57.932021Z INFO request{method=POST path=/attach-hook request_id=2697503c-7b3e-4529-b8c1-d12ef912d3eb}: Request handled, status: 200 OK
2024-01-22T19:07:58.898213Z INFO Got SIGQUIT. Terminating
2024-01-22T19:08:02.176588Z INFO version: git-env:d56f31639356ed8e8ce832097f132f27ee19ac8a, launch_timestamp: 2024-01-22 19:08:02.174634554 UTC, build_tag build_tag-env:7615750160, state at /tmp/test_output/test_pageserver_max_throughput_getpage_at_latest_lsn[10-13-30]/repo/attachments.json, listening on 127.0.0.1:15048
thread 'main' panicked at /__w/neon/neon/control_plane/attachment_service/src/persistence.rs:95:17:
Failed to load state from '/tmp/test_output/test_pageserver_max_throughput_getpage_at_latest_lsn[10-13-30]/repo/attachments.json': trailing characters at line 1 column 8957 (maybe your .neon/ dir was written by an older version?)
stack backtrace:
0: rust_begin_unwind
at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/std/src/panicking.rs:645:5
1: core::panicking::panic_fmt
at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/core/src/panicking.rs:72:14
2: attachment_service::persistence::PersistentState::load_or_new::{{closure}}
at ./control_plane/attachment_service/src/persistence.rs:95:17
3: attachment_service::persistence::Persistence:🆕:{{closure}}
at ./control_plane/attachment_service/src/persistence.rs:103:56
4: attachment_service::main::{{closure}}
at ./control_plane/attachment_service/src/main.rs:69:61
5: tokio::runtime::park::CachedParkThread::block_on::{{closure}}
at ./.cargo/registry/src/index.crates.io-6f17d22bba15001f/tokio-1.34.0/src/runtime/park.rs:282:63
6: tokio::runtime::coop::with_budget
at ./.cargo/registry/src/index.crates.io-6f17d22bba15001f/tokio-1.34.0/src/runtime/coop.rs:107:5
7: tokio::runtime::coop::budget
at ./.cargo/registry/src/index.crates.io-6f17d22bba15001f/tokio-1.34.0/src/runtime/coop.rs:73:5
8: tokio::runtime::park::CachedParkThread::block_on
at ./.cargo/registry/src/index.crates.io-6f17d22bba15001f/tokio-1.34.0/src/runtime/park.rs:282:31
9: tokio::runtime::context::blocking::BlockingRegionGuard::block_on
at ./.cargo/registry/src/index.crates.io-6f17d22bba15001f/tokio-1.34.0/src/runtime/context/blocking.rs:66:9
10: tokio::runtime::scheduler::multi_thread::MultiThread::block_on::{{closure}}
at ./.cargo/registry/src/index.crates.io-6f17d22bba15001f/tokio-1.34.0/src/runtime/scheduler/multi_thread/mod.rs:87:13
11: tokio::runtime::context::runtime::enter_runtime
at ./.cargo/registry/src/index.crates.io-6f17d22bba15001f/tokio-1.34.0/src/runtime/context/runtime.rs:65:16
12: tokio::runtime::scheduler::multi_thread::MultiThread::block_on
at ./.cargo/registry/src/index.crates.io-6f17d22bba15001f/tokio-1.34.0/src/runtime/scheduler/multi_thread/mod.rs:86:9
13: tokio::runtime::runtime::Runtime::block_on
at ./.cargo/registry/src/index.crates.io-6f17d22bba15001f/tokio-1.34.0/src/runtime/runtime.rs:350:50
14: attachment_service::main
at ./control_plane/attachment_service/src/main.rs:99:5
15: core::ops::function::FnOnce::call_once
at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/core/src/ops/function.rs:250:5
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
```
The attachment_service handles SIGQUIT by just exiting the process.
In theory, the SIGQUIT could come in while we're writing out the
`attachments.json`.
Now, in above log output, there's a 1 second gap between the last
request completing
and the SIGQUIT coming in. So, there must be some other issue.
But, let's have this change anyways, maybe it helps uncover the real
cause for the test failure.
## Problem
tenant_id/timeline_id is no longer a full identifier for metrics from a
`Tenant` or `Timeline` object.
Closes: https://github.com/neondatabase/neon/issues/5953
## Summary of changes
Include `shard_id` label everywhere we have `tenant_id`/`timeline_id`
label.
