Commit Graph

1724 Commits

Author SHA1 Message Date
Joonas Koivunen
f010479107 feat(layer): pageserver_layer_redownloaded_after histogram (#6132)
this is aimed at replacing the current mtime only based trashing
alerting later.

Cc: #5331
2023-12-14 21:32:54 +02:00
Conrad Ludgate
cc633585dc gauge guards (#6138)
## Problem

The websockets gauge for active db connections seems to be growing more
than the gauge for client connections over websockets, which does not
make sense.

## Summary of changes

refactor how our counter-pair gauges are represented. not sure if this
will improve the problem, but it should be harder to mess-up the
counters. The API is much nicer though now and doesn't require
scopeguard::defer hacks
2023-12-14 17:21:39 +00:00
John Spray
c4e0ef507f pageserver: heatmap uploads (#6050)
Dependency (commits inline):
https://github.com/neondatabase/neon/pull/5842

## Problem

Secondary mode tenants need a manifest of what to download. Ultimately
this will be some kind of heat-scored set of layers, but as a robust
first step we will simply use the set of resident layers: secondary
tenant locations will aim to match the on-disk content of the attached
location.

## Summary of changes

- Add heatmap types representing the remote structure
- Add hooks to Tenant/Timeline for generating these heatmaps
- Create a new `HeatmapUploader` type that is external to `Tenant`, and
responsible for walking the list of attached tenants and scheduling
heatmap uploads.

Notes to reviewers:
- Putting the logic for uploads (and later, secondary mode downloads)
outside of `Tenant` is an opinionated choice, motivated by:
- Enable future smarter scheduling of operations, e.g. uploading the
stalest tenant first, rather than having all tenants compete for a fair
semaphore on a first-come-first-served basis. Similarly for downloads,
we may wish to schedule the tenants with the hottest un-downloaded
layers first.
- Enable accessing upload-related state without synchronization (it
belongs to HeatmapUploader, rather than being some Mutex<>'d part of
Tenant)
- Avoid further expanding the scope of Tenant/Timeline types, which are
already among the largest in the codebase
- You might reasonably wonder how much of the uploader code could be a
generic job manager thing. Probably some of it: but let's defer pulling
that out until we have at least two users (perhaps secondary downloads
will be the second one) to highlight which bits are really generic.

Compromises:
- Later, instead of using digests of heatmaps to decide whether anything
changed, I would prefer to avoid walking the layers in tenants that
don't have changes: tracking that will be a bit invasive, as it needs
input from both remote_timeline_client and Layer.
2023-12-14 13:09:24 +00:00
Joonas Koivunen
a919b863d1 refactor: remove eviction batching (#6060)
We no longer have `layer_removal_cs` since #5108, we no longer need
batching.
2023-12-13 18:05:33 +02:00
Joonas Koivunen
2d22661061 refactor: calculate_synthetic_size_worker, remove PRE::NeedsDownload (#6111)
Changes I wanted to make on #6106 but decided to leave out to keep that
commit clean for including in the #6090. Finally remove
`PageReconstructionError::NeedsDownload`.
2023-12-13 14:23:19 +00:00
Konstantin Knizhnik
aec1acdbac Do not inherite replication slots in branch (#5898)
## Problem
 
See 
https://github.com/neondatabase/company_projects/issues/111
https://neondb.slack.com/archives/C03H1K0PGKH/p1700166126954079


## Summary of changes

Do not search for AUX_FILES_KEY in parent timelines

## 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: Arseny Sher <sher-ars@yandex.ru>
2023-12-12 14:24:21 +02:00
Konstantin Knizhnik
8bb4a13192 Do not materialize null images in PS (#5979)
## Problem

PG16 is writing null images during relation extension.
And page server implements optimisation which replace WAL record with
FPI with page image.
So instead of WAL record ~30 bytes we store 8kb null page image.
Ans this image is almost useless, because most likely it will be shortly
rewritten with actual page content.

## Summary of changes

Do not materialize wal records with null page FPI.
 
## 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>
2023-12-12 14:23:45 +02:00
John Spray
fead836f26 swagger: remove 'format: hex' from tenant IDs (#6099)
## Problem

TenantId is changing to TenantShardId in many APIs. The swagger had
`format: hex` attributes on some of these IDs. That isn't formally
defined anywhere, but a reasonable person might think it means "hex
digits only", which will no longer be the case once we start using
shard-aware IDs (they're like `<tenant_id>-0001`).



## Summary of changes

- Remove these `format` attributes from all `tenant_id` fields in the
swagger definition
2023-12-12 10:39:34 +00:00
John Spray
20e9cf7d31 pageserver: tweaks to slow/hung task logging (#6098)
## Problem

- `shutdown_tasks` would log when a particular task was taking a long
time to shut down, but not when it eventually completed. That left one
uncertain as to whether the slow task was the source of a hang, or just
a precursor.

## Summary of changes

- Add a log line after a slow task shutdown
- Add an equivalent in Gate's `warn_if_stuck`, in case we ever need it.
This isn't related to the original issue but was noticed when checking
through these logging paths.
2023-12-12 07:19:59 +00:00
Joonas Koivunen
3b04f3a749 fix: accidential return Ok (#6106)
Error indicating request cancellation OR timeline shutdown was deemed as
a reason to exit the background worker that calculated synthetic size.
Fix it to only be considered for avoiding logging such of such errors.
2023-12-11 21:27:53 +00:00
Arpad Müller
c49fd69bd6 Add initdb_lsn to TimelineInfo (#6104)
This way, we can query it.

Background: I want to do statistics for how reproducible `initdb_lsn`
really is, see https://github.com/neondatabase/cloud/issues/8284 and
https://neondb.slack.com/archives/C036U0GRMRB/p1701895218280269
2023-12-11 21:08:14 +00:00
John Spray
f1fc1fd639 pageserver: further refactoring from TenantId to TenantShardId (#6059)
## Problem

In https://github.com/neondatabase/neon/pull/5957, the most essential
types were updated to use TenantShardId rather than TenantId. That
unblocked other work, but didn't fully enable running multiple shards
from the same tenant on the same pageserver.

## Summary of changes

- Use TenantShardId in page cache key for materialized pages
- Update mgr.rs get_tenant() and list_tenants() functions to use a shard
id, and update all callers.
- Eliminate the exactly_one_or_none helper in mgr.rs and all code that
used it
- Convert timeline HTTP routes to use tenant_shard_id

Note on page cache:
```
struct MaterializedPageHashKey {
    /// Why is this TenantShardId rather than TenantId?
    ///
    /// Usually, the materialized value of a page@lsn is identical on any shard in the same tenant.  However, this
    /// this not the case for certain internally-generated pages (e.g. relation sizes).  In future, we may make this
    /// key smaller by omitting the shard, if we ensure that reads to such pages always skip the cache, or are
    /// special-cased in some other way.
    tenant_shard_id: TenantShardId,
    timeline_id: TimelineId,
    key: Key,
}
```
2023-12-11 15:52:33 +00:00
Christian Schwarz
cf024de202 virtual_file metrics: expose max size of the fd cache (#6078)
And also leave a comment on how to determine current size.

Kind of follow-up to #6066

refs https://github.com/neondatabase/cloud/issues/8351
refs https://github.com/neondatabase/neon/issues/5479
2023-12-08 17:23:50 +00:00
Conrad Ludgate
e1a564ace2 proxy simplify cancellation (#5916)
## Problem

The cancellation code was confusing and error prone (as seen before in
our memory leaks).

## Summary of changes

* Use the new `TaskTracker` primitve instead of JoinSet to gracefully
wait for tasks to shutdown.
* Updated libs/utils/completion to use `TaskTracker`
* Remove `tokio::select` in favour of `futures::future::select` in a
specialised `run_until_cancelled()` helper function
2023-12-08 16:21:17 +00:00
Christian Schwarz
f5b9af6ac7 page cache: improve eviction-related metrics (#6077)
These changes help with identifying thrashing.

The existing `pageserver_page_cache_find_victim_iters_total` is already
useful, but, it doesn't tell us how many individual find_victim() calls
are happening, only how many clock-LRU steps happened in the entire
system,
without info about whether we needed to actually evict other data vs
just scan for a long time, e.g., because the cache is large.

The changes in this PR allows us to
1. count each possible outcome separately, esp evictions
2. compute mean iterations/outcome

I don't think anyone except me was paying close attention to
`pageserver_page_cache_find_victim_iters_total` before, so,
I think the slight behavior change of also counting iterations
for the 'iters exceeded' case is fine.

refs https://github.com/neondatabase/cloud/issues/8351
refs https://github.com/neondatabase/neon/issues/5479
2023-12-08 15:27:21 +00:00
John Spray
2c544343e0 pageserver: filtered WAL ingest for sharding (#6024)
## Problem

Currently, if one creates many shards they will all ingest all the data:
not much use! We want them to ingest a proportional share of the data
each.

Closes: #6025

## Summary of changes

- WalIngest object gets a copy of the ShardIdentity for the Tenant it
was created by.
- While iterating the `blocks` part of a decoded record, blocks that do
not match the current shard are ignored, apart from on shard zero where
they are used to update relation sizes in `observe_decoded_block` (but
not stored).
- Before committing a `DataDirModificiation` from a WAL record, we check
if it's empty, and drop the record if so. This check is necessary
(rather than just looking at the `blocks` part) because certain record
types may modify blocks in non-obvious ways (e.g.
`ingest_heapam_record`).
- Add WAL ingest metrics to record the total received, total committed,
and total filtered out
- Behaviour for unsharded tenants is unchanged: they will continue to
ingest all blocks, and will take the fast path through `is_key_local`
that doesn't bother calculating any hashes.

After this change, shards store a subset of the tenant's total data, and
accurate relation sizes are only maintained on shard zero.

---------

Co-authored-by: Arpad Müller <arpad-m@users.noreply.github.com>
2023-12-08 10:12:37 +00:00
Arpad Müller
7914eaf1e6 Buffer initdb.tar.zst to a temporary file before upload (#5944)
In https://github.com/neondatabase/neon/pull/5912#pullrequestreview-1749982732 , Christian liked the idea of using files instead of buffering the
archive to RAM for the *download* path. This is for the upload path,
which is a very similar situation.
2023-12-08 03:33:44 +01:00
Joonas Koivunen
37fdbc3aaa fix: use larger buffers for remote storage (#6069)
Currently using 8kB buffers, raise that to 32kB to hopefully 1/4 of
`spawn_blocking` usage. Also a drive-by fixing of last `tokio::io::copy`
to `tokio::io::copy_buf`.
2023-12-07 19:36:44 +00:00
Christian Schwarz
f2892d3798 virtual_file metrics: distinguish first and subsequent open() syscalls (#6066)
This helps with identifying thrashing.

I don't love the name, but, there is already "close-by-replace".

While reading the code, I also found a case where we waste
work in a cache pressure situation:
https://github.com/neondatabase/neon/issues/6065

refs https://github.com/neondatabase/cloud/issues/8351
2023-12-07 16:17:33 +00:00
Joonas Koivunen
b492cedf51 fix(remote_storage): buffering, by using streams for upload and download (#5446)
There is double buffering in remote_storage and in pageserver for 8KiB
in using `tokio::io::copy` to read `BufReader<ReaderStream<_>>`.

Switches downloads and uploads to use `Stream<Item =
std::io::Result<Bytes>>`. Caller and only caller now handles setting up
buffering. For reading, `Stream<Item = ...>` is also a `AsyncBufRead`,
so when writing to a file, we now have `tokio::io::copy_buf` reading
full buffers and writing them to `tokio::io::BufWriter` which handles
the buffering before dispatching over to `tokio::fs::File`.

Additionally implements streaming uploads for azure. With azure
downloads are a bit nicer than before, but not much; instead of one huge
vec they just hold on to N allocations we got over the wire.

This PR will also make it trivial to switch reading and writing to
io-uring based methods.

Cc: #5563.
2023-12-07 15:52:22 +00:00
John Spray
e89e41f8ba tests: update for tenant generations (#5449)
## Problem

Some existing tests are written in a way that's incompatible with tenant
generations.

## Summary of changes

Update all the tests that need updating: this is things like calling
through the NeonPageserver.tenant_attach helper to get a generation
number, instead of calling directly into the pageserver API. There are
various more subtle cases.
2023-12-07 12:27:16 +00:00
Joonas Koivunen
52718bb8ff fix(layer): metric splitting, span rename (#5902)
Per [feedback], split the Layer metrics, also finally account for lost
and [re-submitted feedback] on `layer_gc` by renaming it to
`layer_delete`, `Layer::garbage_collect_on_drop` renamed to
`Layer::delete_on_drop`. References to "gc" dropped from metric names
and elsewhere.

Also fixes how the cancellations were tracked: there was one rare
counter. Now there is a top level metric for cancelled inits, and the
rare "download failed but failed to communicate" counter is kept.

Fixes: #6027

[feedback]: https://github.com/neondatabase/neon/pull/5809#pullrequestreview-1720043251
[re-submitted feedback]: https://github.com/neondatabase/neon/pull/5108#discussion_r1401867311
2023-12-07 11:39:40 +02:00
Joonas Koivunen
10c77cb410 temp: increase the wait tenant activation timeout (#6058)
5s is causing way too much noise; this is of course a temporary fix, we
should prioritize tenants for which there are pagestream openings the
highest, second highest the basebackups.

Deployment thread for context:
https://neondb.slack.com/archives/C03H1K0PGKH/p1701935048144479?thread_ts=1701765158.926659&cid=C03H1K0PGKH
2023-12-07 09:01:08 +00:00
Heikki Linnakangas
31be301ef3 Make simple_rcu::RcuWaitList::wait() async (#6046)
The gc_timeline() function is async, but it calls the synchronous wait()
function. In the worst case, that could lead to a deadlock by using up
all tokio executor threads.

In the passing, fix a few typos in comments.

Fixes issue #6045.

---------

Co-authored-by: Joonas Koivunen <joonas@neon.tech>
2023-12-07 10:20:40 +02:00
Joonas Koivunen
a3c7d400b4 fix: avoid allocations with logging a slug (#6047)
to_string forces allocating a less than pointer sized string (costing on
stack 4 usize), using a Display formattable slug saves that. the
difference seems small, but at the same time, we log these a lot.
2023-12-07 07:25:22 +00:00
Christian Schwarz
987c9aaea0 virtual_file: fix the metric for close() calls done by VirtualFile::drop (#6051)
Before this PR we would inc() the counter for `Close` even though the
slot's FD had already been closed.

Especially visible when subtracting `open` from `close+close-by-replace`
on a system that does a lot of attach and detach.

refs https://github.com/neondatabase/cloud/issues/8440
refs https://github.com/neondatabase/cloud/issues/8351
2023-12-06 12:05:28 +00:00
John Spray
483caa22c6 pageserver: logging tweaks (#6039)
- The `Attaching tenant` log message omitted some useful information
like the generation and mode
- info-level messages about writing configuration files were
unnecessarily verbose
- During process shutdown, we don't emit logs about the various phases:
this is very cheap to log since we do it once per process lifetime, and
is helpful when figuring out where something got stuck during a hang.
2023-12-05 16:11:15 +00:00
John Spray
da5e03b0d8 pageserver: add a /reset API for tenants (#6014)
## Problem

Traditionally we would detach/attach directly with curl if we wanted to
"reboot" a single tenant. That's kind of inconvenient these days,
because one needs to know a generation number to issue an attach
request.

Closes: https://github.com/neondatabase/neon/issues/6011

## Summary of changes

- Introduce a new `/reset` API, which remembers the LocationConf from
the current attachment so that callers do not have to work out the
correct configuration/generation to use.
- As an additional support tool, allow an optional `drop_cache` query
parameter, for situations where we are concerned that some on-disk state
might be bad and want to clear that as well as the in-memory state.

One might wonder why I didn't call this "reattach" -- it's because
there's already a PS->CP API of that name and it could get confusing.
2023-12-05 15:38:27 +00:00
John Spray
be885370f6 pageserver: remove redundant unsafe_create_dir_all (#6040)
This non-fsyncing analog to our safe directory creation function was
just duplicating what tokio's fs::create_dir_all does.
2023-12-05 15:03:07 +00:00
John Spray
61fe9d360d pageserver: add Key->Shard mapping logic & use it in page service (#5980)
## Problem

When a pageserver receives a page service request identified by
TenantId, it must decide which `Tenant` object to route it to.

As in earlier PRs, this stuff is all a no-op for tenants with a single
shard: calls to `is_key_local` always return true without doing any
hashing on a single-shard ShardIdentity.

Closes: https://github.com/neondatabase/neon/issues/6026

## Summary of changes

- Carry immutable `ShardIdentity` objects in Tenant and Timeline. These
provide the information that Tenants/Timelines need to figure out which
shard is responsible for which Key.
- Augment `get_active_tenant_with_timeout` to take a `ShardSelector`
specifying how the shard should be resolved for this tenant. This mode
depends on the kind of request (e.g. basebackups always go to shard
zero).
- In `handle_get_page_at_lsn_request`, handle the case where the
Timeline we looked up at connection time is not the correct shard for
the page being requested. This can happen whenever one node holds
multiple shards for the same tenant. This is currently written as a
"slow path" with the optimistic expectation that usually we'll run with
one shard per pageserver, and the Timeline resolved at connection time
will be the one serving page requests. There is scope for optimization
here later, to avoid doing the full shard lookup for each page.
- Omit consumption metrics from nonzero shards: only the 0th shard is
responsible for tracing accurate relation sizes.

Note to reviewers:
- Testing of these changes is happening separately on the
`jcsp/sharding-pt1` branch, where we have hacked neon_local etc needed
to run a test_pg_regress.
- The main caveat to this implementation is that page service
connections still look up one Timeline when the connection is opened,
before they know which pages are going to be read. If there is one shard
per pageserver then this will always also be the Timeline that serves
page requests. However, if multiple shards are on one pageserver then
get page requests will incur the cost of looking up the correct Timeline
on each getpage request. We may look to improve this in future with a
"sticky" timeline per connection handler so that subsequent requests for
the same Timeline don't have to look up again, and/or by having postgres
pass a shard hint when connecting. This is tracked in the "Loose ends"
section of https://github.com/neondatabase/neon/issues/5507
2023-12-05 12:01:55 +00:00
Christian Schwarz
c7f1143e57 concurrency-limit low-priority initial logical size calculation [v2] (#6000)
Problem
-------

Before this PR, there was no concurrency limit on initial logical size
computations.

While logical size computations are lazy in theory, in practice
(production), they happen in a short timeframe after restart.

This means that on a PS with 20k tenants, we'd have up to 20k concurrent
initial logical size calculation requests.

This is self-inflicted needless overload.

This hasn't been a problem so far because the `.await` points on the
logical size calculation path never return `Pending`, hence we have a
natural concurrency limit of the number of executor threads.
But, as soon as we return `Pending` somewhere in the logical size
calculation path, other concurrent tasks get scheduled by tokio.
If these other tasks are also logical size calculations, they eventually
pound on the same bottleneck.

For example, in #5479, we want to switch the VirtualFile descriptor
cache to a `tokio::sync::RwLock`, which makes us return `Pending`, and
without measures like this patch, after PS restart, VirtualFile
descriptor cache thrashes heavily for 2 hours until all the logical size
calculations have been computed and the degree of concurrency /
concurrent VirtualFile operations is down to regular levels.
See the *Experiment* section below for details.

<!-- Experiments (see below) show that plain #5479 causes heavy
thrashing of the VirtualFile descriptor cache.
The high degree of concurrency is too much for 
In the case of #5479 the VirtualFile descriptor cache size starts
thrashing heavily.


-->

Background
----------

Before this PR, initial logical size calculation was spawned lazily on
first call to `Timeline::get_current_logical_size()`.

In practice (prod), the lazy calculation is triggered by
`WalReceiverConnectionHandler` if the timeline is active according to
storage broker, or by the first iteration of consumption metrics worker
after restart (`MetricsCollection`).

The spawns by walreceiver are high-priority because logical size is
needed by Safekeepers (via walreceiver `PageserverFeedback`) to enforce
the project logical size limit.
The spawns by metrics collection are not on the user-critical path and
hence low-priority. [^consumption_metrics_slo]

[^consumption_metrics_slo]: We can't delay metrics collection
indefintely because there are TBD internal SLOs tied to metrics
collection happening in a timeline manner
(https://github.com/neondatabase/cloud/issues/7408). But let's ignore
that in this issue.

The ratio of walreceiver-initiated spawns vs
consumption-metrics-initiated spawns can be reconstructed from logs
(`spawning logical size computation from context of task kind {:?}"`).
PR #5995 and #6018 adds metrics for this.

First investigation of the ratio lead to the discovery that walreceiver
spawns 75% of init logical size computations.
That's because of two bugs:
- In Safekeepers: https://github.com/neondatabase/neon/issues/5993
- In interaction between Pageservers and Safekeepers:
https://github.com/neondatabase/neon/issues/5962

The safekeeper bug is likely primarily responsible but we don't have the
data yet. The metrics will hopefully provide some insights.

When assessing production-readiness of this PR, please assume that
neither of these bugs are fixed yet.


Changes In This PR
------------------

With this PR, initial logical size calculation is reworked as follows:

First, all initial logical size calculation task_mgr tasks are started
early, as part of timeline activation, and run a retry loop with long
back-off until success. This removes the lazy computation; it was
needless complexity because in practice, we compute all logical sizes
anyways, because consumption metrics collects it.

Second, within the initial logical size calculation task, each attempt
queues behind the background loop concurrency limiter semaphore. This
fixes the performance issue that we pointed out in the "Problem" section
earlier.

Third, there is a twist to queuing behind the background loop
concurrency limiter semaphore. Logical size is needed by Safekeepers
(via walreceiver `PageserverFeedback`) to enforce the project logical
size limit. However, we currently do open walreceiver connections even
before we have an exact logical size. That's bad, and I'll build on top
of this PR to fix that
(https://github.com/neondatabase/neon/issues/5963). But, for the
purposes of this PR, we don't want to introduce a regression, i.e., we
don't want to provide an exact value later than before this PR. The
solution is to introduce a priority-boosting mechanism
(`GetLogicalSizePriority`), allowing callers of
`Timeline::get_current_logical_size` to specify how urgently they need
an exact value. The effect of specifying high urgency is that the
initial logical size calculation task for the timeline will skip the
concurrency limiting semaphore. This should yield effectively the same
behavior as we had before this PR with lazy spawning.

Last, the priority-boosting mechanism obsoletes the `init_order`'s grace
period for initial logical size calculations. It's a separate commit to
reduce the churn during review. We can drop that commit if people think
it's too much churn, and commit it later once we know this PR here
worked as intended.

Experiment With #5479 
---------------------

I validated this PR combined with #5479 to assess whether we're making
forward progress towards asyncification.

The setup is an `i3en.3xlarge` instance with 20k tenants, each with one
timeline that has 9 layers.
All tenants are inactive, i.e., not known to SKs nor storage broker.
This means all initial logical size calculations are spawned by
consumption metrics `MetricsCollection` task kind.
The consumption metrics worker starts requesting logical sizes at low
priority immediately after restart. This is achieved by deleting the
consumption metrics cache file on disk before starting
PS.[^consumption_metrics_cache_file]

[^consumption_metrics_cache_file] Consumption metrics worker persists
its interval across restarts to achieve persistent reporting intervals
across PS restarts; delete the state file on disk to get predictable
(and I believe worst-case in terms of concurrency during PS restart)
behavior.

Before this patch, all of these timelines would all do their initial
logical size calculation in parallel, leading to extreme thrashing in
page cache and virtual file cache.

With this patch, the virtual file cache thrashing is reduced
significantly (from 80k `open`-system-calls/second to ~500
`open`-system-calls/second during loading).


### Critique

The obvious critique with above experiment is that there's no skipping
of the semaphore, i.e., the priority-boosting aspect of this PR is not
exercised.

If even just 1% of our 20k tenants in the setup were active in
SK/storage_broker, then 200 logical size calculations would skip the
limiting semaphore immediately after restart and run concurrently.

Further critique: given the two bugs wrt timeline inactive vs active
state that were mentioned in the Background section, we could have 75%
of our 20k tenants being (falsely) active on restart.

So... (next section)

This Doesn't Make Us Ready For Async VirtualFile
------------------------------------------------

This PR is a step towards asynchronous `VirtualFile`, aka, #5479 or even
#4744.

But it doesn't yet enable us to ship #5479.

The reason is that this PR doesn't limit the amount of high-priority
logical size computations.
If there are many high-priority logical size calculations requested,
we'll fall over like we did if #5479 is applied without this PR.
And currently, at very least due to the bugs mentioned in the Background
section, we run thousands of high-priority logical size calculations on
PS startup in prod.

So, at a minimum, we need to fix these bugs.

Then we can ship #5479 and #4744, and things will likely be fine under
normal operation.

But in high-traffic situations, overload problems will still be more
likely to happen, e.g., VirtualFile cache descriptor thrashing.
The solution candidates for that are orthogonal to this PR though:
* global concurrency limiting
* per-tenant rate limiting => #5899
* load shedding
* scaling bottleneck resources (fd cache size (neondatabase/cloud#8351),
page cache size(neondatabase/cloud#8351), spread load across more PSes,
etc)

Conclusion
----------

Even with the remarks from in the previous section, we should merge this
PR because:
1. it's an improvement over the status quo (esp. if the aforementioned
bugs wrt timeline active / inactive are fixed)
2. it prepares the way for
https://github.com/neondatabase/neon/pull/6010
3. it gets us close to shipping #5479 and #4744
2023-12-04 17:22:26 +00:00
Christian Schwarz
7403d55013 walredo: stderr cleanup & make explicitly cancel safe (#6031)
# Problem

I need walredo to be cancellation-safe for
https://github.com/neondatabase/neon/pull/6000#discussion_r1412049728

# Solution

We are only `async fn` because of
`wait_for(stderr_logger_task_done).await`, added in #5560 .

The `stderr_logger_cancel` and `stderr_logger_task_done` were there out
of precaution that the stderr logger task might for some reason not stop
when the walredo process terminates.
That hasn't been a problem in practice.
So, simplify things:
- remove `stderr_logger_cancel` and the
`wait_for(...stderr_logger_task_done...)`
- use `tokio::process::ChildStderr` in the stderr logger task
- add metrics to track number of running stderr logger tasks so in case
I'm wrong here, we can use these metrics to identify the issue (not
planning to put them into a dashboard or anything)
2023-12-04 16:06:41 +00:00
John Khvatov
eae49ff598 Perform L0 compaction before creating new image layers (#5950)
If there are too many L0 layers before compaction, the compaction
process becomes slow because of slow `Timeline::get`. As a result of the
slowdown, the pageserver will generate even more L0 layers for the next
iteration, further exacerbating the slow performance.

Change to perform L0 -> L1 compaction before creating new images. The
simple change speeds up compaction time and `Timeline::get` to 5x.
`Timeline::get` is faster on top of L1 layers.

Co-authored-by: Joonas Koivunen <joonas@neon.tech>
2023-12-04 12:35:09 +00:00
John Spray
1d81e70d60 pageserver: tweak logs for index_part loading (#6005)
## Problem

On pageservers upgraded to enable generations, these INFO level logs
were rather frequent. If a tenant timeline hasn't written new layers
since the upgrade, it will emit the "No index_part.json*" log every time
it starts.

## Summary of changes

- Downgrade two log lines from info to debug
- Add a tiny unit test that I wrote for sanity-checking that there
wasn't something wrong with our Generation-comparing logic when loading
index parts.
2023-12-04 09:57:47 +00:00
Christian Schwarz
e43cde7aba initial logical size: remove CALLS metric from hot path (#6018)
Only introduced a few hours ago (#5995), I took a look at the numbers
from staging and realized that `get_current_logical_size()` is on the
walingest hot path: we call it for every `ReplicationMessage::XLogData`
that we receive.

Since the metric is global, it would be quite a busy cache line.

This PR replaces it with a new metric purpose-built for what's most
interesting right now.
2023-12-01 22:45:04 +01:00
Joonas Koivunen
711425cc47 fix: use create_new instead of create for mutex file (#6012)
Using create_new makes the uninit marker work as a mutual exclusion
primitive. Temporary hopefully.
2023-12-01 18:30:51 +02:00
bojanserafimov
fd81945a60 Use TEST_OUTPUT envvar in pageserver (#5984) 2023-12-01 09:16:24 -05:00
bojanserafimov
e49c21a3cd Speed up rel extend (#5983) 2023-12-01 09:11:41 -05:00
Christian Schwarz
ce1652990d logical size: better represent level of accuracy in the type system (#5999)
I would love to not expose the in-accurate value int he mgmt API at all,
and in fact control plane doesn't use it [^1].
But our tests do, and I have no desire to change them at this time.

[^1]: https://github.com/neondatabase/cloud/pull/8317
2023-12-01 14:16:29 +01:00
Christian Schwarz
8cd28e1718 logical size calculation: make .current_size() infallible (#5999)
... by panicking on overflow;

It was made fallible initially due to in-confidence in logical size
calculation. However, the error has never happened since I am at Neon.

Let's stop worrying about this by converting the overflow check into a panic.
2023-12-01 14:16:29 +01:00
Christian Schwarz
1c88824ed0 initial logical size calculation: add a bunch of metrics (#5995)
These will help us answer questions such as:
- when & at what do calculations get started after PS restart?
- how often is the api to get current incrementally-computed logical
  size called, and does it return Exact vs Approximate?

I'd also be interested in a histogram of how much wall clock
time size calculations take, but, I don't know good bucket sizes,
and, logging it would introduce yet another per-timeline log
message during startup; don't think that's worth it just yet.

Context

- https://neondb.slack.com/archives/C033RQ5SPDH/p1701197668789769
- https://github.com/neondatabase/neon/issues/5962
- https://github.com/neondatabase/neon/issues/5963
- https://github.com/neondatabase/neon/pull/5955
- https://github.com/neondatabase/cloud/issues/7408
2023-12-01 12:52:59 +01:00
Arpad Müller
1ce1c82d78 Clean up local state if index_part.json request gives 404 (#6009)
If `index_part.json` is (verifiably) not present on remote storage, we
should regard the timeline as inexistent. This lets `clean_up_timelines`
purge the partial local disk state, which is important in the case of
incomplete creations leaving behind state that hinders retries. For
incomplete deletions, we also want the timeline's local disk content be
gone completely.

The PR removes the allowed warnings added by #5390 and #5912, as we now
are only supposed to issue info level messages. It also adds a
reproducer for #6007, by parametrizing the
`test_timeline_init_break_before_checkpoint_recreate` test added by
#5390. If one reverts the .rs changes, the "cannot create its uninit
mark file" log line occurs once one comments out the failing checks for
the local disk state being actually empty.

Closes #6007

---------

Co-authored-by: Joonas Koivunen <joonas@neon.tech>
2023-12-01 10:58:06 +00:00
Arpad Müller
b71b8ecfc2 Add existing_initdb_timeline_id param to timeline creation (#5912)
This PR adds an `existing_initdb_timeline_id` option to timeline
creation APIs, taking an optional timeline ID.

Follow-up of  #5390.

If the `existing_initdb_timeline_id` option is specified via the HTTP
API, the pageserver downloads the existing initdb archive from the given
timeline ID and extracts it, instead of running initdb itself.

---------

Co-authored-by: Christian Schwarz <christian@neon.tech>
2023-11-30 22:32:04 +01:00
John Spray
57ae9cd07f pageserver: add flush_ms and document /location_config API (#5860)
- During migration of tenants, it is useful for callers to
`/location_conf` to flush a tenant's layers while transitioning to
AttachedStale: this optimization reduces the redundant WAL replay work
that the tenant's new attached pageserver will have to do. Test coverage
for this will come as part of the larger tests for live migration in
#5745 #5842
- Flushing is controlled with `flush_ms` query parameter: it is the
caller's job to decide how long they want to wait for a flush to
complete. If flush is not complete within the time limit, the pageserver
proceeds to succeed anyway: flushing is only an optimization.
- Add swagger definitions for all this: the location_config API is the
primary interface for driving tenant migration as described in
docs/rfcs/028-pageserver-migration.md, and will eventually replace the
various /attach /detach /load /ignore APIs.

---------

Co-authored-by: Joonas Koivunen <joonas@neon.tech>
2023-11-30 14:22:07 +00:00
Christian Schwarz
3bb1030f5d walingest: refactor if-cascade on decoded.xl_rmid into match statement (#5974)
refs https://github.com/neondatabase/neon/issues/5962

---------

Co-authored-by: Joonas Koivunen <joonas@neon.tech>
2023-11-30 14:07:41 +00:00
Joonas Koivunen
1e57ddaabc fix: flush loop should also keep the gate open (#5987)
I was expecting this to already be in place, because this should not
conflict how we shutdown (0. cancel, 1. shutdown_tasks, 2. close gate).
2023-11-30 14:26:11 +02:00
Christian Schwarz
292281c9df pagectl: add subcommand to rewrite layer file summary (#5933)
Part of getpage@lsn benchmark epic:
https://github.com/neondatabase/neon/issues/5771
2023-11-30 11:34:30 +00:00
Rahul Modpur
50d959fddc refactor: use serde for TenantConf deserialization Fixes: #5300 (#5310)
Remove handcrafted TenantConf deserialization code. Use
`serde_path_to_error` to include the field which failed parsing. Leaves
the duplicated TenantConf in pageserver and models, does not touch
PageserverConf handcrafted deserialization.

Error change:
- before change: "configure option `checkpoint_distance` cannot be
negative"
- after change: "`checkpoint_distance`: invalid value: integer `-1`,
expected u64"

Fixes: #5300
Cc: #3682

---------

Signed-off-by: Rahul Modpur <rmodpur2@gmail.com>
Co-authored-by: Shany Pozin <shany@neon.tech>
Co-authored-by: Joonas Koivunen <joonas@neon.tech>
2023-11-30 12:47:13 +02:00
Christian Schwarz
ca597206b8 walredo: latency histogram for spawn duration (#5925)
fixes https://github.com/neondatabase/neon/issues/5891
2023-11-29 18:44:37 +00:00
John Spray
9e55ad4796 pageserver: refactor TenantId to TenantShardId in Tenant & Timeline (#5957)
(includes two preparatory commits from
https://github.com/neondatabase/neon/pull/5960)

## Problem

To accommodate multiple shards in the same tenant on the same
pageserver, we must include the full TenantShardId in local paths. That
means that all code touching local storage needs to see the
TenantShardId.

## Summary of changes

- Replace `tenant_id: TenantId` with `tenant_shard_id: TenantShardId` on
Tenant, Timeline and RemoteTimelineClient.
- Use TenantShardId in helpers for building local paths.
- Update all the relevant call sites.

This doesn't update absolutely everything: things like PageCache,
TaskMgr, WalRedo are still shard-naive. The purpose of this PR is to
update the core types so that others code can be added/updated
incrementally without churning the most central shared types.
2023-11-29 14:52:35 +00:00