## 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
PR #9993 was supposed to enable `page_service_pipelining` by default for
all `NeonEnv`s, but this was ineffective in our CI environment.
Thus, CI Python-based tests and benchmarks, unless explicitly
configuring pipelining, were still using serial protocol handling.
## Analysis
The root cause was that in our CI environment,
`config.compatibility_neon_binpath` is always Truthy.
It's not in local environments, which is why this slipped through in
local testing.
Lesson: always add a log line ot pageserver startup and spot-check tests
to ensure the intended default is picked up.
## Summary of changes
Fix it. Since enough time has passed, the compatiblity snapshot contains
a recent enough software version so we don't need to worry about
`compatibility_neon_binpath` anymore.
## Future Work
The question how to add a new default except for compatibliity tests,
which is what the broken code was supposed to do, is still unsolved.
Slack discussion:
https://neondb.slack.com/archives/C059ZC138NR/p1737490501941309
## Problem
part of https://github.com/neondatabase/neon/issues/9114
The automatic trigger is already implemented at
https://github.com/neondatabase/neon/pull/10221 but I need to write some
tests and finish my experiments in staging before I can merge it with
confidence. Given that I have some other patches that will modify the
config items, I'd like to get the config items merged first to reduce
conflicts.
## Summary of changes
* add `l2_lsn` to index_part.json -- below that LSN, data have been
processed by gc-compaction
* add a set of gc-compaction auto trigger control items into the config
---------
Signed-off-by: Alex Chi Z <chi@neon.tech>
We did not have any tests on fast_import binary yet.
In this PR I have introduced:
- `FastImport` class and tools for testing in python
- basic test that runs fast import against vanilla postgres and checks
that data is there
Should be merged after https://github.com/neondatabase/neon/pull/10251
We currently have some flakiness in
`test_scrubber_physical_gc_ancestors`, see #10391.
The first flakiness kind is about the reconciler not actually becoming
idle within the timeout of 30 seconds. We see continuous forward
progress so this is likely not a hang. We also see this happen in
parallel to a test failure, so is likely due to runners being
overloaded. Therefore, we increase the timeout.
The second flakiness kind is an assertion failure. This one is a little
bit more tricky, but we saw in the successful run that there was some
advance of the lsn between the compaction ran (which created layer
files) and the gc run. Apparently gc rejects reductions to the single
image layer setting if the cutoff lsn is the same as the lsn of the
image layer: it will claim that that layer is newer than the space
cutoff and therefore skip it, while thinking the old layer (that we want
to delete) is the latest one (so it's not deleted).
We address the second flakiness kind by inserting a tiny amount of WAL
between the compaction and gc. This should hopefully fix things.
Related issue: #10391
(not closing it with the merger of the PR as we'll need to validate that
these changes had the intended effect).
Thanks to Chi for going over this together with me in a call.
Otherwise we might hit ERRORs in otherwise safe situations (such as user
queries), which isn't a great user experience.
## Problem
https://github.com/neondatabase/neon/pull/10376
## Summary of changes
Instead of accepting internal errors as acceptable, we ensure we don't
exceed our allocated usage.
# Refs
- fixes https://github.com/neondatabase/neon/issues/10309
- fixup of batching design, first introduced in
https://github.com/neondatabase/neon/pull/9851
- refinement of https://github.com/neondatabase/neon/pull/8339
# Problem
`Tenant::shutdown` was occasionally taking many minutes (sometimes up to
20) in staging and prod if the
`page_service_pipelining.mode="concurrent-futures"` is enabled.
# Symptoms
The issue happens during shard migration between pageservers.
There is page_service unavailability and hence effectively downtime for
customers in the following case:
1. The source (state `AttachedStale`) gets stuck in `Tenant::shutdown`,
waiting for the gate to close.
2. Cplane/Storcon decides to transition the target `AttachedMulti` to
`AttachedSingle`.
3. That transition comes with a bump of the generation number, causing
the `PUT .../location_config` endpoint to do a full `Tenant::shutdown` /
`Tenant::attach` cycle for the target location.
4. That `Tenant::shutdown` on the target gets stuck, waiting for the
gate to close.
5. Eventually the gate closes (`close completed`), correlating with a
`page_service` connection handler logging that it's exiting because of a
network error (`Connection reset by peer` or `Broken pipe`).
While in (4):
- `Tenant::shutdown` is stuck waiting for all `Timeline::shutdown` calls
to complete.
So, really, this is a `Timeline::shutdown` bug.
- retries from Cplane/Storcon to complete above state transitions, fail
with errors related to the tenant mgr slot being in state
`TenantSlot::InProgress`, the tenant state being
`TenantState::Stopping`, and the timelines being in
`TimelineState::Stopping`, and the `Timeline::cancel` being cancelled.
- Existing (and/or new?) page_service connections log errors `error
reading relation or page version: Not found: Timed out waiting 30s for
tenant active state. Latest state: None`
# Root-Cause
After a lengthy investigation ([internal
write-up](https://www.notion.so/neondatabase/2025-01-09-batching-deadlock-Slow-Log-Analysis-in-Staging-176f189e00478050bc21c1a072157ca4?pvs=4))
I arrived at the following root cause.
The `spsc_fold` channel (`batch_tx`/`batch_rx`) that connects the
Batcher and Executor stages of the pipelined mode was storing a `Handle`
and thus `GateGuard` of the Timeline that was not shutting down.
The design assumption with pipelining was that this would always be a
short transient state.
However, that was incorrect: the Executor was stuck on writing/flushing
an earlier response into the connection to the client, i.e., socket
write being slow because of TCP backpressure.
The probable scenario of how we end up in that case:
1. Compute backend process sends a continuous stream of getpage prefetch
requests into the connection, but never reads the responses (why this
happens: see Appendix section).
2. Batch N is processed by Batcher and Executor, up to the point where
Executor starts flushing the response.
3. Batch N+1 is procssed by Batcher and queued in the `spsc_fold`.
4. Executor is still waiting for batch N flush to finish.
5. Batcher eventually hits the `TimeoutReader` error (10min).
From here on it waits on the
`spsc_fold.send(Err(QueryError(TimeoutReader_error)))`
which will never finish because the batch already inside the `spsc_fold`
is not
being read by the Executor, because the Executor is still stuck in the
flush.
(This state is not observable at our default `info` log level)
6. Eventually, Compute backend process is killed (`close()` on the
socket) or Compute as a whole gets killed (probably no clean TCP
shutdown happening in that case).
7. Eventually, Pageserver TCP stack learns about (6) through RST packets
and the Executor's flush() call fails with an error.
8. The Executor exits, dropping `cancel_batcher` and its end of the
spsc_fold.
This wakes Batcher, causing the `spsc_fold.send` to fail.
Batcher exits.
The pipeline shuts down as intended.
We return from `process_query` and log the `Connection reset by peer` or
`Broken pipe` error.
The following diagram visualizes the wait-for graph at (5)
```mermaid
flowchart TD
Batcher --spsc_fold.send(TimeoutReader_error)--> Executor
Executor --flush batch N responses--> socket.write_end
socket.write_end --wait for TCP window to move forward--> Compute
```
# Analysis
By holding the GateGuard inside the `spsc_fold` open, the pipelining
implementation
violated the principle established in
(https://github.com/neondatabase/neon/pull/8339).
That is, that `Handle`s must only be held across an await point if that
await point
is sensitive to the `<Handle as Deref<Target=Timeline>>::cancel` token.
In this case, we were holding the Handle inside the `spsc_fold` while
awaiting the
`pgb_writer.flush()` future.
One may jump to the conclusion that we should simply peek into the
spsc_fold to get
that Timeline cancel token and be sensitive to it during flush, then.
But that violates another principle of the design from
https://github.com/neondatabase/neon/pull/8339.
That is, that the page_service connection lifecycle and the Timeline
lifecycles must be completely decoupled.
Tt must be possible to shut down one shard without shutting down the
page_service connection, because on that single connection we might be
serving other shards attached to this pageserver.
(The current compute client opens separate connections per shard, but,
there are plans to change that.)
# Solution
This PR adds a `handle::WeakHandle` struct that does _not_ hold the
timeline gate open.
It must be `upgrade()`d to get a `handle::Handle`.
That `handle::Handle` _does_ hold the timeline gate open.
The batch queued inside the `spsc_fold` only holds a `WeakHandle`.
We only upgrade it while calling into the various `handle_` methods,
i.e., while interacting with the `Timeline` via `<Handle as
Deref<Target=Timeline>>`.
All that code has always been required to be (and is!) sensitive to
`Timeline::cancel`, and therefore we're guaranteed to bail from it
quickly when `Timeline::shutdown` starts.
We will drop the `Handle` immediately, before we start
`pgb_writer.flush()`ing the responses.
Thereby letting go of our hold on the `GateGuard`, allowing the timeline
shutdown to complete while the page_service handler remains intact.
# Code Changes
* Reproducer & Regression Test
* Developed and proven to reproduce the issue in
https://github.com/neondatabase/neon/pull/10399
* Add a `Test` message to the pagestream protocol (`cfg(feature =
"testing")`).
* Drive-by minimal improvement to the parsing code, we now have a
`PagestreamFeMessageTag`.
* Refactor `pageserver/client` to allow sending and receiving
`page_service` requests independently.
* Add a Rust helper binary to produce situation (4) from above
* Rationale: (4) and (5) are the same bug class, we're holding a gate
open while `flush()`ing.
* Add a Python regression test that uses the helper binary to
demonstrate the problem.
* Fix
* Introduce and use `WeakHandle` as explained earlier.
* Replace the `shut_down` atomic with two enum states for `HandleInner`,
wrapped in a `Mutex`.
* To make `WeakHandle::upgrade()` and `Handle::downgrade()`
cache-efficient:
* Wrap the `Types::Timeline` in an `Arc`
* Wrap the `GateGuard` in an `Arc`
* The separate `Arc`s enable uncontended cloning of the timeline
reference in `upgrade()` and `downgrade()`.
If instead we were `Arc<Timeline>::clone`, different connection handlers
would be hitting the same cache line on every upgrade()/downgrade(),
causing contention.
* Please read the udpated module-level comment in `mod handle`
module-level comment for details.
# Testing & Performance
The reproducer test that failed before the changes now passes, and
obviously other tests are passing as well.
We'll do more testing in staging, where the issue happens every ~4h if
chaos migrations are enabled in storcon.
Existing perf testing will be sufficient, no perf degradation is
expected.
It's a few more alloctations due to the added Arc's, but, they're low
frequency.
# Appendix: Why Compute Sometimes Doesn't Read Responses
Remember, the whole problem surfaced because flush() was slow because
Compute was not reading responses. Why is that?
In short, the way the compute works, it only advances the page_service
protocol processing when it has an interest in data, i.e., when the
pagestore smgr is called to return pages.
Thus, if compute issues a bunch of requests as part of prefetch but then
it turns out it can service the query without reading those pages, it
may very well happen that these messages stay in the TCP until the next
smgr read happens, either in that session, or possibly in another
session.
If there’s too many unread responses in the TCP, the pageserver kernel
is going to backpressure into userspace, resulting in our stuck flush().
All of this stems from the way vanilla Postgres does prefetching and
"async IO":
it issues `fadvise()` to make the kernel do the IO in the background,
buffering results in the kernel page cache.
It then consumes the results through synchronous `read()` system calls,
which hopefully will be fast because of the `fadvise()`.
If it turns out that some / all of the prefetch results are not needed,
Postgres will not be issuing those `read()` system calls.
The kernel will eventually react to that by reusing page cache pages
that hold completed prefetched data.
Uncompleted prefetch requests may or may not be processed -- it's up to
the kernel.
In Neon, the smgr + Pageserver together take on the role of the kernel
in above paragraphs.
In the current implementation, all prefetches are sent as GetPage
requests to Pageserver.
The responses are only processed in the places where vanilla Postgres
would do the synchronous `read()` system call.
If we never get to that, the responses are queued inside the TCP
connection, which, once buffers run full, will backpressure into
Pageserver's sending code, i.e., the `pgb_writer.flush()` that was the
root cause of the problems we're fixing in this PR.
## Problem
`test_storage_controller_node_deletion` sometimes failed because shards
were moving around during timeline creation, and neon_local isn't
tolerant of that. The movements were unexpected because the shards had
only just been created.
This was a regression from #9916Closes: #10383
## Summary of changes
- Make this test use multiple AZs -- this makes the storage controller's
scheduling reliably stable
Why this works: in #9916 , I made a simplifying assumption that we would
have multiple AZs to get nice stable scheduling -- it's much easier,
because each tenant has a well defined primary+secondary location when
they have an AZ preference and nodes have different AZs. Everything
still works if you don't have multiple AZs, but you just have this quirk
that sometimes the optimizer can disagree with initial scheduling, so
once in a while a shard moves after being created -- annoying for tests,
harmless IRL.
## Problem
All pageserver have the same application name which makes it hard to
distinguish them.
## Summary of changes
Include the node id in the application name sent to the safekeeper. This
should gives us
more visibility in logs. There's a few metrics that will increase in
cardinality by `pageserver_count`,
but that's fine.
Rename the safekeeper scheduling policy "disabled" to "pause".
A rename was requested in
https://github.com/neondatabase/neon/pull/10400#discussion_r1916259124,
as the "disabled" policy is meant to be analogous to the "pause" policy
for pageservers.
Also simplify the `SkSchedulingPolicyArg::from_str` function, relying on
the `from_str` implementation of `SkSchedulingPolicy`. Latter is used
for the database format as well, so it is quite stable. If we ever want
to change the UI, we'll need to duplicate the function again but this is
cheap.
## Problem
Threads spawned in `test_tenant_delete_races_timeline_creation` are not
joined before the test ends, and can generate
`PytestUnhandledThreadExceptionWarning` in other tests.
https://neon-github-public-dev.s3.amazonaws.com/reports/pr-10419/12805365523/index.html#/testresult/53a72568acd04dbd
## Summary of changes
- Wrap threads in ThreadPoolExecutor which will join them before the
test ends
- Remove a spurious deletion call -- the background thread doing
deletion ought to succeed.
This should fix the largest source of flakyness of
test_nbtree_pagesplit_cycleid.
## Problem
https://github.com/neondatabase/neon/issues/10390
## Summary of changes
By using a guaranteed-flushed LSN, we ensure that PS won't have to wait
forever.
(If it does wait forever, we know the issue can't be with Compute's WAL)
## Problem
part of https://github.com/neondatabase/neon/issues/9114
part of investigation of
https://github.com/neondatabase/neon/issues/10049
## Summary of changes
* If `cfg!(test) or cfg!(feature = testing)`, then we will always try
generating an image to ensure the history is replayable, but not put the
image layer into the final layer results, therefore discovering wrong
key history before we hit a read error.
* I suspect it's easier to trigger some races if gc-compaction is
continuously run on a timeline, so I increased the frequency to twice
per 10 churns.
* Also, create branches in gc-compaction smoke tests to get more test
coverage.
---------
Signed-off-by: Alex Chi Z <chi@neon.tech>
Co-authored-by: Arpad Müller <arpad@neon.tech>
Implementing the last missing endpoint of #9981, this adds support to
set the scheduling policy of an individual safekeeper, as specified in
the RFC. However, unlike in the RFC we call the endpoint
`scheduling_policy` not `status`
Closes#9981.
As for why not use the upsert endpoint for this: we want to have the
safekeeper upsert endpoint be used for testing and for deploying new
safekeepers, but not for changes of the scheduling policy. We don't want
to change any of the other fields when marking a safekeeper as
decommissioned for example, so we'd have to first fetch them only to
then specify them again. Of course one can also design an endpoint where
one can omit any field and it doesn't get modified, but it's still not
great for observability to put everything into one big "change something
about this safekeeper" endpoint.
## Problem
https://github.com/neondatabase/neon/issues/9965
## Summary of changes
Add to safekeeper http endpoint to switch membership configuration. Also
add it to python client for tests, and add simple test itself.
## Problem
https://github.com/neondatabase/neon/issues/9965
## Summary of changes
Add safekeeper membership configuration struct itself and storing it in
the control file. In passing also add creation timestamp to the control
file (there were cases where I wanted it in the past).
Remove obsolete unused PersistedPeerInfo struct from control file (still
keep it control_file_upgrade.rs to have it in old upgrade code).
Remove the binary representation of cfile in the roundtrip test.
Updating it is annoying, and we still test the actual roundtrip.
Also add configuration to timeline creation http request, currently used
only in one python test. In passing, slightly change LSNs meaning in the
request: normally start_lsn is passed (the same as ancestor_start_lsn in
similar pageserver call), but we allow specifying higher commit_lsn for
manual intervention if needed. Also when given LSN initialize
term_history with it.
## Problem
For large deployments, the `control/v1/tenant` listing API can time out
transmitting a monolithic serialized response.
## Summary of changes
- Add `limit` and `start_after` parameters to listing API
- Update storcon_cli to use these parameters and limit requests to 1000
items at a time
## Problem
See https://github.com/neondatabase/neon/issues/10167
Too small number of `max_connections` (2) can cause failures of
test_physical_replication_config_mismatch_too_many_known_xids test
## Summary of changes
Increase `max_connections` to 5
Co-authored-by: Konstantin Knizhnik <knizhnik@neon.tech>
## Problem
We want to do a more robust job of scheduling tenants into their home
AZ: https://github.com/neondatabase/neon/issues/8264.
Closes: https://github.com/neondatabase/neon/issues/8969
## Summary of changes
### Scope
This PR combines prioritizing AZ with a larger rework of how we do
optimisation. The rationale is that just bumping AZ in the order of
Score attributes is a very tiny change: the interesting part is lining
up all the optimisation logic to respect this properly, which means
rewriting it to use the same scores as the scheduler, rather than the
fragile hand-crafted logic that we had before. Separating these changes
out is possible, but would involve doing two rounds of test updates
instead of one.
### Scheduling optimisation
`TenantShard`'s `optimize_attachment` and `optimize_secondary` methods
now both use the scheduler to pick a new "favourite" location. Then
there is some refined logic for whether + how to migrate to it:
- To decide if a new location is sufficiently "better", we generate
scores using some projected ScheduleContexts that exclude the shard
under consideration, so that we avoid migrating from a node with
AffinityScore(2) to a node with AffinityScore(1), only to migrate back
later.
- Score types get a `for_optimization` method so that when we compare
scores, we will only do an optimisation if the scores differ by their
highest-ranking attributes, not just because one pageserver is lower in
utilization. Eventually we _will_ want a mode that does this, but doing
it here would make scheduling logic unstable and harder to test, and to
do this correctly one needs to know the size of the tenant that one is
migrating.
- When we find a new attached location that we would like to move to, we
will create a new secondary location there, even if we already had one
on some other node. This handles the case where we have a home AZ A, and
want to migrate the attachment between pageservers in that AZ while
retaining a secondary location in some other AZ as well.
- A unit test is added for
https://github.com/neondatabase/neon/issues/8969, which is implicitly
fixed by reworking optimisation to use the same scheduling scores as
scheduling.
## Problem
Currently, if we want to move a secondary there isn't a neat way to do
that: we just have migration API for the attached location, and it is
only clean to use that if you've manually created a secondary via
pageserver API in the place you're going to move it to.
Secondary migration API enables:
- Moving the secondary somewhere because we would like to later move the
attached location there.
- Move the secondary location because we just want to reclaim some disk
space from its current location.
## Summary of changes
- Add `/migrate_secondary` API
- Add `tenant-shard-migrate-secondary` CLI
- Add tests for above
## Problem
We would sometimes fail to retry compute notifications:
1. Try and send, set compute_notify_failure if we can't
2. On next reconcile, reconcile() fails for some other reason (e.g.
tried to talk to an offline node), and we fail the `result.is_ok() &&
must_notify` condition around the re-sending.
Closes: https://github.com/neondatabase/cloud/issues/22612
## Summary of changes
- Clarify the meaning of the reconcile result: it should be Ok(()) if
configuring attached location worked, even if secondary or detach
locations cannot be reached.
- Skip trying to talk to secondaries if they're offline
- Even if reconcile fails and we can't send the compute notification (we
can't send it because we're not sure if it's really attached), make sure
we save the `compute_notify_failure` flag so that subsequent reconciler
runs will try again
- Add a regression test for the above
For testing the proxy's websockets support.
I wrote this to test https://github.com/neondatabase/neon/issues/3822.
Unfortunately, that bug can *not* be reproduced with this tunnel. The
bug only appears when the client pipelines the first query with the
authentication messages. The tunnel doesn't do that.
---
Update (@conradludgate 2025-01-10):
We have since added some websocket tests, but they manually implemented
a very simplistic setup of the postgres protocol. Introducing the tunnel
would make more complex testing simpler in the future.
---------
Co-authored-by: Conrad Ludgate <conradludgate@gmail.com>
## Problem
These two tests came up in #9537 as doing multi-gigabyte I/O, and from
inspection of the tests it doesn't seem like they need that to fulfil
their purpose.
## Summary of changes
- In test_local_file_cache_unlink, run fewer background threads with a
smaller number of rows. These background threads AFAICT exist to make
sure some I/O is going on while we unlink the LFC directory, but 5
threads should be enough for "some".
- In test_lfc_resize, tweak the test to validate that the cache size is
larger than the final size before resizing it, so that we're sure we're
writing enough data to really be doing something. Then decrease the
pgbench scale.
## Problem
This test writes ~5GB of data. It is not suitable to run in parallel
with all the other small tests in test_runner/regress.
via #9537
## Summary of changes
- Move test_parallel_copy into the performance directory, so that it
does not run in parallel with other tests
## Problem
I noticed in https://github.com/neondatabase/neon/pull/9537 that tests
which work with compat snapshots were writing several hundred MB of
data, which isn't really necessary.
Also, the snapshots are large but don't have the proper variety of
storage format features, e.g. they could just have L0 deltas.
## Summary of changes
- Use smaller scale factor and runtime to generate less data
- Configure a small layer size and use force image layer generation so
that our output contains L1 deltas and image layers, and has a decent
number of entries in the layer map
## Problem
Auto-offloading as requested by the compaction task is racy with
unarchival, in that the compaction task might attempt to offload an
unarchived timeline. By that point it will already have set the timeline
to the `Stopping` state however, which makes it unusable for any
purpose. For example:
1. compaction task decides to offload timeline
2. timeline gets unarchived
3. `offload_timeline` gets called by compaction task
* sets timeline's state to `Stopping`
* realizes that the timeline can't be unarchived, errors out
6. endpoint can't be started as the timeline is `Stopping` and thus
'can't be found'.
A future iteration of the compaction task can't "heal" this state either
as the timeline will still not be archived, same goes for other
automatic stuff. The only way to heal this is a tenant detach+attach, or
alternatively a pageserver restart.
Furthermore, the compaction task is especially amenable for such races
as it first stores `can_offload` into a variable, figures out whether
compaction is needed (which takes some time), and only then does it
attempt an offload operation: the time difference between "check" and
"use" is non-trivially small.
To make it even worse, we start the compaction task right after attach
of a tenant, and it is a common pattern by pageserver users to attach a
tenant to then immediately unarchive a timeline, so that an endpoint can
be started.
## Solutions not adopted
The simplest solution is to move the `can_offload` check to right before
attempting of the offload. But this is not a good solution, as no lock
is held between that check and timeline shutdown. So races would still
be possible, just become less likely.
I explored using the timeline state for this, as in adding an additional
enum variant. But `Timeline::set_state` is racy (#10297).
## Adopted solution
We use the lock on the timeline's upload queue as an arbiter: either
unarchival gets to it first and sours the state for auto-offloading, or
auto-offloading shuts it down, which stops any parallel unarchival in
its tracks. The key part is not releasing the upload queue's lock
between the check whether the timeline is archived or not, and shutting
it down (the actual implementation only sets `shutting_down` but it has
the same effect on `initialized_mut()` as a full shutdown). The rest of
the patch is stuff that follows from this.
We also move the part where we set the state to `Stopping` to after that
arbiter has decided the fate of the timeline. For deletions, we do keep
it inside `DeleteTimelineFlow::prepare` however, so that it is called
with all of the the timelines locks held that the function allocates
(timelines lock most importantly). This is only a precautionary measure
however, as I didn't want to analyze deletion related code for possible
races.
## Future changes
It might make sense to move `can_offload` to right before the offload
attempt. Maybe some other properties might have changed as well.
Although this will not be perfect either as no lock is held. I want to
keep it out of this change to emphasize that this move wasn't the main
reason we are race free now.
Fixes#10220
## Problem
In Postgres, one cannot drop a role if it has any dependent objects in
the DB. In `compute_ctl`, we automatically reassign all dependent
objects in every DB to the corresponding DB owner. Yet, it seems that it
doesn't help with some implicit permissions. The issue is reproduced by
installing a `postgis` extension because it creates some views and
tables in the public schema.
## Summary of changes
Added a repro test without using a `postgis`: i) create a role via
`compute_ctl` (with `neon_superuser` grant); ii) create a test role, a
table in schema public, and grant permissions via the role in
`neon_superuser`.
To fix the issue, I added a new `compute_ctl` code that removes such
dangling permissions before dropping the role. It's done in the least
invasive way, i.e., only touches the schema public, because i) that's
the problem we had with PostGIS; ii) it creates a smaller chance of
messing anything up and getting a stuck operation again, just for a
different reason.
Properly, any API-based catalog operations should fail gracefully and
provide an actionable error and status code to the control plane,
allowing the latter to unwind the operation and propagate an error
message and hint to the user. In this sense, it's aligned with another
feature request https://github.com/neondatabase/cloud/issues/21611Resolveneondatabase/cloud#13582
## Problem
The filtered record metric doesn't make sense for interpreted ingest.
## Summary of changes
While of dubious utility in the first place, this patch replaces them
with records received and records observed metrics for interpreted
ingest:
* received records cause the pageserver to do _something_: write a key,
value pair to storage, update some metadata or flush pending
modifications
* observed records are a shard 0 concept and contain only key metadata
used in tracking relation sizes (received records include observed
records)
## Problem
Project gets stuck if database with subscriptions was deleted via API /
UI.
https://github.com/neondatabase/cloud/issues/18646
## Summary of changes
Before dropping the database, drop all the subscriptions in it.
Do not drop slot on publisher, because we have no guarantee that the
slot still exists or that the publisher is reachable.
Add `DropSubscriptionsForDeletedDatabases` phase to run these operations
in all databases, we're about to delete.
Ignore the error if the database does not exist.
## Problem
Typical deployments of neon have some tenants that stay in use
continuously, and a background churning population of tenants that are
created and then fall idle, and are configured to Detached state.
Currently, this churn of short lived tenants results in an
ever-increasing memory footprint.
Closes: https://github.com/neondatabase/neon/issues/9712
## Summary of changes
- At startup, filter to only load shards that don't have Detached policy
- In process_result, check if a tenant's shards are all Detached and
observed=={}, and if so drop them from memory
- In tenant_location_conf and other tenant mutators, load the tenants'
shards on-demand if they are not present
## Problem
The observed state removal may race with the inline updates of the
observed state done from `Service::node_activate_reconcile`.
This was intended to work as follows:
1. Detaches while the node is unavailable remove the entry from the
observed state.
2. `Service::node_activate_reconcile` diffs the locations returned
by the pageserver with the observed state and detaches in-line
when required.
## Summary of changes
This PR removes step (1) and lets background reconciliations
deal with the mismatch between the intent and observed state.
A follow up will attempt to remove `Service::node_activate_reconcile`
altogether.
Closes https://github.com/neondatabase/neon/issues/10253
## Problem
It's impossible to run regression tests with Python 3.13 as some
dependencies don't support it (some of them are outdated, and `jsonnet`
doesn't support it at all yet)
## Summary of changes
- Update dependencies for Python 3.13
- Install `jsonnet` only on Python < 3.13 and skip relevant tests on
Python 3.13
Closes#10237
## Problem
We see periodic failures in `test_scrubber_physical_gc_ancestors`, where
the logs show that the pageserver is creating image layers that should
cause child shards to no longer reference their parents' layers, but
then the scrubber runs and doesn't find any unreferenced layers.[
https://neon-github-public-dev.s3.amazonaws.com/reports/pr-10256/12582034135/index.html#/testresult/78ea06dea6ba8dd3
From inspecting the code & test, it seems like this could be as simple
as the test failing to wait for uploads before running the scrubber. It
had a 2 second delay built in to satisfy the scrubbers time threshold
checks, which on a lightly loaded machine would also have been easily
enough for uploads to complete, but our test machines are more heavily
loaded all the time.
## Summary of changes
- Wait for uploads to complete after generating images layers in
test_scrubber_physical_gc_ancestors, so that the scrubber should
reliably see the post-compaction metadata.
## Problem
`test_pgdata_import_smoke` writes two gigabytes of pages and then reads
them back serially. This is CPU bottlenecked and results in a long
runtime, and sensitivity to CPU load from other tests on the same
machine.
Closes: https://github.com/neondatabase/neon/issues/10071
## Summary of changes
- Use effective_io_concurrency=32 when doing sequential scans through
2GiB of pages in test_pgdata_import_smoke. This is a ~10x runtime
decrease in the parts of the test that do sequential scans.
- Also set `effective_io_concurrency=2` for tests, as I noticed while
debugging that we were doing all getpage requests serially, which is bad
for checking the stability of the batching code.
## Problem
We want to verify how much / if pgbench throughput and latency on Neon
suffers if the database contains many other relations, too.
## Summary of changes
Modify the benchmarking.yml pgbench-compare job to
- create an addiitional project at scale factor 10 GiB
- before running pgbench add n tables (initially 10k) to the database
- then compare the pgbench throughput and latency to the existing
pgbench-compare at 10 Gib scale factor
We use a realistic template for the n relations that is a partitioned
table with some realistic data types, indexes and constraints - similar
to a table that we use internally.
Example run:
https://github.com/neondatabase/neon/actions/runs/12377565956/job/34547386959
## Problem
In https://github.com/neondatabase/neon/pull/8103 we changed the test
case to have more test coverage of gc_compaction. Now that we have
`test_gc_compaction_smoke`, we can revert this test case to serve its
original purpose and revert the parameter changes.
part of https://github.com/neondatabase/neon/issues/9114
## Summary of changes
* Revert pitr_interval from 60s to 10s.
* Assert the physical/logical size ratio in the benchmark.
---------
Signed-off-by: Alex Chi Z <chi@neon.tech>
Co-authored-by: Arpad Müller <arpad-m@users.noreply.github.com>
## Problem
We cannot get the size of the compaction queue and access the info.
Part of #9114
## Summary of changes
* Add an API endpoint to get the compaction queue.
* gc_compaction test case now waits until the compaction finishes.
---------
Signed-off-by: Alex Chi Z <chi@neon.tech>
## Problem
part of https://github.com/neondatabase/neon/issues/9114
In https://github.com/neondatabase/neon/pull/10127 we fixed the race,
but we didn't add the errors to the allowlist.
## Summary of changes
* Allow repartition errors in the gc-compaction smoke test.
I think it might be worth to refactor the code to allow multiple threads
getting a copy of repartition status (i.e., using Rcu) in the future.
Signed-off-by: Alex Chi Z <chi@neon.tech>
Add a `safekeepers` subcommand to `storcon_cli` that allows listing the
safekeepers.
```
$ curl -X POST --url http://localhost:1234/control/v1/safekeeper/42 --data \
'{"active":true, "id":42, "created_at":"2023-10-25T09:11:25Z", "updated_at":"2024-08-28T11:32:43Z","region_id":"neon_local","host":"localhost","port":5454,"http_port":0,"version":123,"availability_zone_id":"us-east-2b"}'
$ cargo run --bin storcon_cli -- --api http://localhost:1234 safekeepers
Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.38s
Running `target/debug/storcon_cli --api 'http://localhost:1234' safekeepers`
+----+---------+-----------+------+-----------+------------+
| Id | Version | Host | Port | Http Port | AZ Id |
+==========================================================+
| 42 | 123 | localhost | 5454 | 0 | us-east-2b |
+----+---------+-----------+------+-----------+------------+
```
Also:
* Don't return the raw `SafekeeperPersistence` struct that contains the
raw database presentation, but instead a new
`SafekeeperDescribeResponse` struct.
* The `SafekeeperPersistence` struct leaves out the `active` field on
purpose because we want to deprecate it and replace it with a
`scheduling_policy` one.
Part of https://github.com/neondatabase/neon/issues/9981
