## Problem
The new communicator gRPC client has significantly worse Pagebench
performance than a basic gRPC client. We need to find out why.
## Summary of changes
Add a `pagebench --profile` flag which takes a client CPU profile of the
benchmark and writes a flamegraph to `profile.svg`.
## Problem
For the communicator scheduling policy, we need to understand the
server-side cost of idle gRPC streams.
Touches #11735.
## Summary of changes
Add an `idle-streams` benchmark to `pagebench` which opens a large
number of idle gRPC GetPage streams.
## Problem
With gRPC `GetPageRequest` batches, we'll have non-trivial
fragmentation/reassembly logic in several places of the stack
(concurrent reads, shard splits, LFC hits, etc). If we included the
block numbers with the pages in `GetPageResponse` we could have better
verification and observability that the final responses are correct.
Touches #11735.
Requires #12480.
## Summary of changes
Add a `Page` struct with`block_number` for `GetPageResponse`, along with
the `RelTag` for completeness, and verify them in the rich gRPC client.
## Problem
`GetPageRequest::request_id` is supposed to be a unique ID for a
request. It's not, because we may retry the request using the same ID.
This causes assertion failures and confusion.
Touches #11735.
Requires #12480.
## Summary of changes
Extend the request ID with a retry attempt, and handle it in the gRPC
client and server.
## Problem
We need to benchmark the rich gRPC client
`client_grpc::PageserverClient` against the basic, no-frills
`page_api::Client` to determine how much overhead it adds.
Touches #11735.
Requires #12476.
## Summary of changes
Add a `pagebench --rich-client` parameter to use
`client_grpc::PageserverClient`. Also adds a compression parameter to
the client.
This patch tightens up `page_api::Client`. It's mostly superficial
changes, but also adds a new constructor that takes an existing gRPC
channel, for use with the communicator connection pool.
## Problem
`compute_ctl` should support gRPC base backups.
Requires #12111.
Requires #12243.
Touches #11926.
## Summary of changes
Support `grpc://` connstrings for `compute_ctl` base backups.
## Problem
gRPC base backups use gRPC compression. However, this has two problems:
* Base backup caching will cache compressed base backups (making gRPC
compression pointless).
* Tonic does not support varying the compression level, and zstd default
level is 10% slower than gzip fastest level.
Touches https://github.com/neondatabase/neon/issues/11728.
Touches https://github.com/neondatabase/cloud/issues/29353.
## Summary of changes
This patch adds a gRPC parameter `BaseBackupRequest::compression`
specifying the compression algorithm. It also moves compression into
`send_basebackup_tarball` to reduce code duplication.
A follow-up PR will integrate the base backup cache with gRPC.
The 1.88.0 stable release is near (this Thursday). We'd like to fix most
warnings beforehand so that the compiler upgrade doesn't require
approval from too many teams.
This is therefore a preparation PR (like similar PRs before it).
There is a lot of changes for this release, mostly because the
`uninlined_format_args` lint has been added to the `style` lint group.
One can read more about the lint
[here](https://rust-lang.github.io/rust-clippy/master/#/uninlined_format_args).
The PR is the result of `cargo +beta clippy --fix` and `cargo fmt`. One
remaining warning is left for the proxy team.
---------
Co-authored-by: Conrad Ludgate <conrad@neon.tech>
This improves `pagebench getpage-latest-lsn` gRPC support by:
* Using `page_api::Client`.
* Removing `--protocol`, and using the `page-server-connstring` scheme
instead.
* Adding `--compression` to enable zstd compression.
## Problem
Pagebench does not support gRPC for `basebackup` benchmarks.
Requires #12243.
Touches #11728.
## Summary of changes
Add gRPC support via gRPC connstrings, e.g. `pagebench basebackup
--page-service-connstring grpc://localhost:51051`.
Also change `--gzip-probability` to `--no-compression`, since this must
be specified per-client for gRPC.
## Problem
The new gRPC page service protocol supports client-side batches. The
current libpq protocol only does best-effort server-side batching.
To compare these approaches, Pagebench should support submitting
contiguous page batches, similar to how Postgres will submit them (e.g.
with prefetches or vectored reads).
## Summary of changes
Add a `--batch-size` parameter specifying the size of contiguous page
batches. One batch counts as 1 RPS and 1 queue depth.
For the libpq protocol, a batch is submitted as individual requests and
we rely on the server to batch them for us. This will give a realistic
comparison of how these would be processed in the wild (e.g. when
Postgres sends 100 prefetch requests).
This patch also adds some basic validation of responses.
## Problem
We need gRPC support in Pagebench to benchmark the new gRPC Pageserver
implementation.
Touches #11728.
## Summary of changes
Adds a `Client` trait to make the client transport swappable, and a gRPC
client via a `--protocol grpc` parameter. This must also specify the
connstring with the gRPC port:
```
pagebench get-page-latest-lsn --protocol grpc --page-service-connstring grpc://localhost:51051
```
The client is implemented using the raw Tonic-generated gRPC client, to
minimize client overhead.
This PR commits the benchmarks I ran to qualify concurrent IO before we
released it.
Changes:
- Add `l0stack` fixture; a reusable abstraction for creating a stack of
L0 deltas
each of which has 1 Value::Delta per page.
- Such a stack of L0 deltas is a good and understandable demo for
concurrent IO
because to reconstruct any page, $layer_stack_height` Values need to be
read.
Before concurrent IO, the reads were sequential.
With concurrent IO, they are executed concurrently.
- So, switch `test_latency` to use the l0stack.
- Teach `pagebench`, which is used by `test_latency`, to limit itself to
the blocks of the relation created by the l0stack abstraction.
- Additional parametrization of `test_latency` over dimensions
`ps_io_concurrency,l0_stack_height,queue_depth`
- Use better names for the tests to reflect what they do, leave
interpretation of the (now quite high-dimensional) results to the reader
- `test_{throughput => postgres_seqscan}`
- `test_{latency => random_reads}`
- Cut down on permutations to those we use in production. Runtime is
about 2min.
Refs
- concurrent IO epic https://github.com/neondatabase/neon/issues/9378
- batching task: fixes https://github.com/neondatabase/neon/issues/9837
---------
Co-authored-by: Peter Bendel <peterbendel@neon.tech>
This makes it easier to add a different client implementation alongside
the current one. I started working on a new gRPC-based protocol to
replace the libpq protocol, which will introduce a new function like
`client_libpq`, but for the new protocol.
It's a little more readable with less indentation anyway.
## Problem
- Part of https://github.com/neondatabase/neon/issues/11113
- Building a new `reqwest::Client` for every request is expensive
because it parses CA certs under the hood. It's noticeable in storcon's
flamegraph.
## Summary of changes
- Reuse one `reqwest::Client` for all API calls to avoid parsing CA
certificates every time.
Migrates the remaining crates 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.
Like the previous migration PRs, this is comprised of three commits:
* the first does the edition update and makes `cargo check`/`cargo
clippy` pass. we had to update bindgen to make its output [satisfy the
requirements of edition
2024](https://doc.rust-lang.org/edition-guide/rust-2024/unsafe-extern.html)
* the second commit does a `cargo fmt` for the new style edition.
* the third commit reorders imports as a one-off change. As before, it
is entirely optional.
Part of #10918
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
## Refs
- Epic: https://github.com/neondatabase/neon/issues/9378
Co-authored-by: Vlad Lazar <vlad@neon.tech>
Co-authored-by: Christian Schwarz <christian@neon.tech>
## Problem
The read path does its IOs sequentially.
This means that if N values need to be read to reconstruct a page,
we will do N IOs and getpage latency is `O(N*IoLatency)`.
## Solution
With this PR we gain the ability to issue IO concurrently within one
layer visit **and** to move on to the next layer without waiting for IOs
from the previous visit to complete.
This is an evolved version of the work done at the Lisbon hackathon,
cf https://github.com/neondatabase/neon/pull/9002.
## Design
### `will_init` now sourced from disk btree index keys
On the algorithmic level, the only change is that the
`get_values_reconstruct_data`
now sources `will_init` from the disk btree index key (which is
PS-page_cache'd), instead
of from the `Value`, which is only available after the IO completes.
### Concurrent IOs, Submission & Completion
To separate IO submission from waiting for its completion, while
simultaneously
feature-gating the change, we introduce the notion of an `IoConcurrency`
struct
through which IO futures are "spawned".
An IO is an opaque future, and waiting for completions is handled
through
`tokio::sync::oneshot` channels.
The oneshot Receiver's take the place of the `img` and `records` fields
inside `VectoredValueReconstructState`.
When we're done visiting all the layers and submitting all the IOs along
the way
we concurrently `collect_pending_ios` for each value, which means
for each value there is a future that awaits all the oneshot receivers
and then calls into walredo to reconstruct the page image.
Walredo is now invoked concurrently for each value instead of
sequentially.
Walredo itself remains unchanged.
The spawned IO futures are driven to completion by a sidecar tokio task
that
is separate from the task that performs all the layer visiting and
spawning of IOs.
That tasks receives the IO futures via an unbounded mpsc channel and
drives them to completion inside a `FuturedUnordered`.
(The behavior from before this PR is available through
`IoConcurrency::Sequential`,
which awaits the IO futures in place, without "spawning" or "submitting"
them
anywhere.)
#### Alternatives Explored
A few words on the rationale behind having a sidecar *task* and what
alternatives were considered.
One option is to queue up all IO futures in a FuturesUnordered that is
polled
the first time when we `collect_pending_ios`.
Firstly, the IO futures are opaque, compiler-generated futures that need
to be polled at least once to submit their IO. "At least once" because
tokio-epoll-uring may not be able to submit the IO to the kernel on
first
poll right away.
Second, there are deadlocks if we don't drive the IO futures to
completion
independently of the spawning task.
The reason is that both the IO futures and the spawning task may hold
some
_and_ try to acquire _more_ shared limited resources.
For example, both spawning task and IO future may try to acquire
* a VirtualFile file descriptor cache slot async mutex (observed during
impl)
* a tokio-epoll-uring submission slot (observed during impl)
* a PageCache slot (currently this is not the case but we may move more
code into the IO futures in the future)
Another option is to spawn a short-lived `tokio::task` for each IO
future.
We implemented and benchmarked it during development, but found little
throughput improvement and moderate mean & tail latency degradation.
Concerns about pressure on the tokio scheduler made us discard this
variant.
The sidecar task could be obsoleted if the IOs were not arbitrary code
but a well-defined struct.
However,
1. the opaque futures approach taken in this PR allows leaving the
existing
code unchanged, which
2. allows us to implement the `IoConcurrency::Sequential` mode for
feature-gating
the change.
Once the new mode sidecar task implementation is rolled out everywhere,
and `::Sequential` removed, we can think about a descriptive submission
& completion interface.
The problems around deadlocks pointed out earlier will need to be solved
then.
For example, we could eliminate VirtualFile file descriptor cache and
tokio-epoll-uring slots.
The latter has been drafted in
https://github.com/neondatabase/tokio-epoll-uring/pull/63.
See the lengthy doc comment on `spawn_io()` for more details.
### Error handling
There are two error classes during reconstruct data retrieval:
* traversal errors: index lookup, move to next layer, and the like
* value read IO errors
A traversal error fails the entire get_vectored request, as before this
PR.
A value read error only fails that value.
In any case, we preserve the existing behavior that once
`get_vectored` returns, all IOs are done. Panics and failing
to poll `get_vectored` to completion will leave the IOs dangling,
which is safe but shouldn't happen, and so, a rate-limited
log statement will be emitted at warning level.
There is a doc comment on `collect_pending_ios` giving more code-level
details and rationale.
### Feature Gating
The new behavior is opt-in via pageserver config.
The `Sequential` mode is the default.
The only significant change in `Sequential` mode compared to before
this PR is the buffering of results in the `oneshot`s.
## Code-Level Changes
Prep work:
* Make `GateGuard` clonable.
Core Feature:
* Traversal code: track `will_init` in `BlobMeta` and source it from
the Delta/Image/InMemory layer index, instead of determining `will_init`
after we've read the value. This avoids having to read the value to
determine whether traversal can stop.
* Introduce `IoConcurrency` & its sidecar task.
* `IoConcurrency` is the clonable handle.
* It connects to the sidecar task via an `mpsc`.
* Plumb through `IoConcurrency` from high level code to the
individual layer implementations' `get_values_reconstruct_data`.
We piggy-back on the `ValuesReconstructState` for this.
* The sidecar task should be long-lived, so, `IoConcurrency` needs
to be rooted up "high" in the call stack.
* Roots as of this PR:
* `page_service`: outside of pagestream loop
* `create_image_layers`: when it is called
* `basebackup`(only auxfiles + replorigin + SLRU segments)
* Code with no roots that uses `IoConcurrency::sequential`
* any `Timeline::get` call
* `collect_keyspace` is a good example
* follow-up: https://github.com/neondatabase/neon/issues/10460
* `TimelineAdaptor` code used by the compaction simulator, unused in
practive
* `ingest_xlog_dbase_create`
* Transform Delta/Image/InMemoryLayer to
* do their values IO in a distinct `async {}` block
* extend the residence of the Delta/Image layer until the IO is done
* buffer their results in a `oneshot` channel instead of straight
in `ValuesReconstructState`
* the `oneshot` channel is wrapped in `OnDiskValueIo` /
`OnDiskValueIoWaiter`
types that aid in expressiveness and are used to keep track of
in-flight IOs so we can print warnings if we leave them dangling.
* Change `ValuesReconstructState` to hold the receiving end of the
`oneshot` channel aka `OnDiskValueIoWaiter`.
* Change `get_vectored_impl` to `collect_pending_ios` and issue walredo
concurrently, in a `FuturesUnordered`.
Testing / Benchmarking:
* Support queue-depth in pagebench for manual benchmarkinng.
* Add test suite support for setting concurrency mode ps config
field via a) an env var and b) via NeonEnvBuilder.
* Hacky helper to have sidecar-based IoConcurrency in tests.
This will be cleaned up later.
More benchmarking will happen post-merge in nightly benchmarks, plus in
staging/pre-prod.
Some intermediate helpers for manual benchmarking have been preserved in
https://github.com/neondatabase/neon/pull/10466 and will be landed in
later PRs.
(L0 layer stack generator!)
Drive-By:
* test suite actually didn't enable batching by default because
`config.compatibility_neon_binpath` is always Truthy in our CI
environment
=> https://neondb.slack.com/archives/C059ZC138NR/p1737490501941309
* initial logical size calculation wasn't always polled to completion,
which was
surfaced through the added WARN logs emitted when dropping a
`ValuesReconstructState` that still has inflight IOs.
* remove the timing histograms
`pageserver_getpage_get_reconstruct_data_seconds`
and `pageserver_getpage_reconstruct_seconds` because with planning,
value read
IO, and walredo happening concurrently, one can no longer attribute
latency
to any one of them; we'll revisit this when Vlad's work on
tracing/sampling
through RequestContext lands.
* remove code related to `get_cached_lsn()`.
The logic around this has been dead at runtime for a long time,
ever since the removal of the materialized page cache in #8105.
## Testing
Unit tests use the sidecar task by default and run both modes in CI.
Python regression tests and benchmarks also use the sidecar task by
default.
We'll test more in staging and possibly preprod.
# Future Work
Please refer to the parent epic for the full plan.
The next step will be to fold the plumbing of IoConcurrency
into RequestContext so that the function signatures get cleaned up.
Once `Sequential` isn't used anymore, we can take the next
big leap which is replacing the opaque IOs with structs
that have well-defined semantics.
---------
Co-authored-by: Christian Schwarz <christian@neon.tech>
## Problem
We have several serious data corruption incidents caused by mismatch of
get-age requests:
https://neondb.slack.com/archives/C07FJS4QF7V/p1723032720164359
We hope that the problem is fixed now. But it is better to prevent such
kind of problems in future.
Part of https://github.com/neondatabase/cloud/issues/16472
## Summary of changes
This PR introduce new V3 version of compute<->pageserver protocol,
adding tag to getpage response.
So now compute is able to check if it really gets response to the
requested page.
## 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
---------
Co-authored-by: Konstantin Knizhnik <knizhnik@neon.tech>
Co-authored-by: Heikki Linnakangas <heikki@neon.tech>
## Problem
Cplane and storage controller tenant config changes are not additive.
Any change overrides all existing tenant configs. This would be fine if
both did client side patching, but that's not the case.
Once this merges, we must update cplane to use the PATCH endpoint.
## Summary of changes
### High Level
Allow for patching of tenant configuration with a `PATCH
/v1/tenant/config` endpoint.
It takes the same data as it's PUT counterpart. For example the payload
below will update `gc_period` and unset `compaction_period`. All other
fields are left in their original state.
```
{
"tenant_id": "1234",
"gc_period": "10s",
"compaction_period": null
}
```
### Low Level
* PS and storcon gain `PATCH /v1/tenant/config` endpoints. PS endpoint
is only used for cplane managed instances.
* `storcon_cli` is updated to have separate commands for
`set-tenant-config` and `patch-tenant-config`
Related https://github.com/neondatabase/cloud/issues/21043
## Problem
Part of https://github.com/neondatabase/neon/issues/8623
## Summary of changes
Removed all aux-v1 config processing code. Note that we persisted it
into the index part file, so we cannot really remove the field from
index part. I also kept the config item within the tenant config, but we
will not read it any more.
---------
Signed-off-by: Alex Chi Z <chi@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>
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 keyspace utils like `is_rel_size_key` or `is_rel_fsm_block_key` and
many others are free functions and have to be either imported separately
or specified with the full path starting in `pageserver_api:🔑:`.
This is less convenient than if these functions were just inherent
impls.
Follow-up of #7890Fixes#6438
Perf shows a significant amount of time is spent on `Keyspace::merge`.
This pull request postpones merging keyspace until retrieving the layer,
which contributes to a 30x improvement in aux keyspace basebackup time.
```
--- old
10000 files found in 0.580569459s
--- new
10000 files found in 0.02995075s
```
Signed-off-by: Alex Chi Z <chi@neon.tech>
part of https://github.com/neondatabase/neon/issues/7462
## Summary of changes
This pull request adds two APIs to the pageserver management API:
list_aux_files and ingest_aux_files. The aux file pagebench is intended
to be used on an empty timeline because the data do not go through the
safekeeper. LSNs are advanced by 8 for each ingestion, to avoid
invariant checks inside the pageserver.
For now, I only care about space amplification / read amplification, so
the bench is designed in a very simple way: ingest 10000 files, and I
will manually dump the layer map to analyze.
---------
Signed-off-by: Alex Chi Z <chi@neon.tech>
In the old protocol version, the client sent with each request:
- latest: bool. If true, the client requested the latest page
version, and the 'lsn' was just a hint of when the page was last
modified
- lsn: Lsn, the page version to return
This protocol didn't allow requesting a page at a particular
non-latest LSN and *also* sending a hint on when the page was last
modified. That put a read only compute into an awkward position where
it had to either request each page at the replay-LSN, which could be
very close to the last LSN written in the primary and therefore
require the pageserver to wait for it to arrive, or an older LSN which
could already be garbage collected in the pageserver, resulting in an
error. The new protocol version fixes that by allowing a read only
compute to send both LSNs.
To use the new protocol version, use "pagestream_v2" command instead
of just "pagestream". The old protocol version is still supported, for
compatibility with old computes (and in fact there is no client
support yet, it is added by the next commit).
## Problem
The API client was written around the same time as some of the server
APIs changed from TenantId to TenantShardId
Closes: https://github.com/neondatabase/neon/issues/6154
## Summary of changes
- Refactor mgmt_api timeline_info and keyspace methods to use
TenantShardId to match the server
This doesn't make pagebench sharding aware, but it paves the way to do
so later.
# 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
## 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.
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
Previously, `GET /v1/tenant/:tenant_id/timeline` and `GET
/v1/tenant/:tenant_id/timeline/:timeline_id`
would bump the priority of the background task which computes the
initial logical size by cancelling
the wait on the synchronisation semaphore. However, the request would
still return an approximate
logical size. It's undesirable to force background work for a status
request.
## Summary of changes
This PR updates the priority used by the timeline status request such
that they don't do priority boosting
by default anymore. An optional query parameter,
`force-await-initial-logical-size`, is added for both
mentioned endpoints. When set to true, it will skip the concurrency
limiting semaphore and wait
for the background task to complete before returning the exact logical
size.
In order to exercise this behaviour in a test I had to add an extra
failpoint. If you think it's too intrusive,
it can be removed.
Also fixeda small bug where the cancellation of a download is reported as an
opaque download failure upstream. This caused `test_location_conf_churn`
to fail at teardown due to a WARN log line.
Closes https://github.com/neondatabase/neon/issues/6168
PR #6266 broke the getpage_latest_lsn benchmark.
Before this patch, we'd fail with
```
not implemented: split up range
```
because `r.start = rel size key` and `r.end = rel size key + 1`.
The filtering of the key ranges in that loop is a bit ugly, but,
I measured:
* setup with 180k layer files (20k tenants * 9 layers).
* total physical size is 463GiB
* 5k tenants, the range filtering takes `0.6 seconds` on an
i3en.3xlarge.
That's a tiny fraction of the overall time it takes for pagebench to get
ready to send requests. So, this is good enough for now / there are
other bottlenecks that are bigger.
This PR adds a component-level benchmarking utility for pageserver.
Its name is `pagebench`.
The problem solved by `pagebench` is that we want to put Pageserver
under high load.
This isn't easily achieved with `pgbench` because it needs to go through
a compute, which has signficant performance overhead compared to
accessing Pageserver directly.
Further, compute has its own performance optimizations (most
importantly: caches). Instead of designing a compute-facing workload
that defeats those internal optimizations, `pagebench` simply bypasses
them by accessing pageserver directly.
Supported benchmarks:
* getpage@latest_lsn
* basebackup
* triggering logical size calculation
This code has no automated users yet.
A performance regression test for getpage@latest_lsn will be added in a
later PR.
part of https://github.com/neondatabase/neon/issues/5771
