See https://github.com/neondatabase/neon/pull/3991
Brings the changes back with the right way to use new `toml_edit` to
deserialize values and a unit test for this.
All non-trivial updates extracted into separate commits, also `carho hakari` data and its manifest format were updated.
3 sets of crates remain unupdated:
* `base64` — touches proxy in a lot of places and changed its api (by 0.21 version) quite strongly since our version (0.13).
* `opentelemetry` and `opentelemetry-*` crates
```
error[E0308]: mismatched types
--> libs/tracing-utils/src/http.rs:65:21
|
65 | span.set_parent(parent_ctx);
| ---------- ^^^^^^^^^^ expected struct `opentelemetry_api::context::Context`, found struct `opentelemetry::Context`
| |
| arguments to this method are incorrect
|
= note: struct `opentelemetry::Context` and struct `opentelemetry_api::context::Context` have similar names, but are actually distinct types
note: struct `opentelemetry::Context` is defined in crate `opentelemetry_api`
--> /Users/someonetoignore/.cargo/registry/src/github.com-1ecc6299db9ec823/opentelemetry_api-0.19.0/src/context.rs:77:1
|
77 | pub struct Context {
| ^^^^^^^^^^^^^^^^^^
note: struct `opentelemetry_api::context::Context` is defined in crate `opentelemetry_api`
--> /Users/someonetoignore/.cargo/registry/src/github.com-1ecc6299db9ec823/opentelemetry_api-0.18.0/src/context.rs:77:1
|
77 | pub struct Context {
| ^^^^^^^^^^^^^^^^^^
= note: perhaps two different versions of crate `opentelemetry_api` are being used?
note: associated function defined here
--> /Users/someonetoignore/.cargo/registry/src/github.com-1ecc6299db9ec823/tracing-opentelemetry-0.18.0/src/span_ext.rs:43:8
|
43 | fn set_parent(&self, cx: Context);
| ^^^^^^^^^^
For more information about this error, try `rustc --explain E0308`.
error: could not compile `tracing-utils` due to previous error
warning: build failed, waiting for other jobs to finish...
error: could not compile `tracing-utils` due to previous error
```
`tracing-opentelemetry` of version `0.19` is not yet released, that is supposed to have the update we need.
* similarly, `rustls`, `tokio-rustls`, `rustls-*` and `tls-listener` crates have similar issue:
```
error[E0308]: mismatched types
--> libs/postgres_backend/tests/simple_select.rs:112:78
|
112 | let mut make_tls_connect = tokio_postgres_rustls::MakeRustlsConnect::new(client_cfg);
| --------------------------------------------- ^^^^^^^^^^ expected struct `rustls::client::client_conn::ClientConfig`, found struct `ClientConfig`
| |
| arguments to this function are incorrect
|
= note: struct `ClientConfig` and struct `rustls::client::client_conn::ClientConfig` have similar names, but are actually distinct types
note: struct `ClientConfig` is defined in crate `rustls`
--> /Users/someonetoignore/.cargo/registry/src/github.com-1ecc6299db9ec823/rustls-0.21.0/src/client/client_conn.rs:125:1
|
125 | pub struct ClientConfig {
| ^^^^^^^^^^^^^^^^^^^^^^^
note: struct `rustls::client::client_conn::ClientConfig` is defined in crate `rustls`
--> /Users/someonetoignore/.cargo/registry/src/github.com-1ecc6299db9ec823/rustls-0.20.8/src/client/client_conn.rs:91:1
|
91 | pub struct ClientConfig {
| ^^^^^^^^^^^^^^^^^^^^^^^
= note: perhaps two different versions of crate `rustls` are being used?
note: associated function defined here
--> /Users/someonetoignore/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-postgres-rustls-0.9.0/src/lib.rs:23:12
|
23 | pub fn new(config: ClientConfig) -> Self {
| ^^^
For more information about this error, try `rustc --explain E0308`.
error: could not compile `postgres_backend` due to previous error
warning: build failed, waiting for other jobs to finish...
```
* aws crates: I could not make new API to work with bucket endpoint overload, and console e2e tests failed.
Other our tests passed, further investigation is worth to be done in https://github.com/neondatabase/neon/issues/4008
Before this patch, if a tenant would override its eviction_policy
setting to use a lower LayerAccessThreshold::threshold than the
`evictions_low_residence_duration_metric_threshold`, the evictions done
for that tenant would count towards the
`evictions_with_low_residence_duration` metric.
That metric is used to identify pre-mature evictions, commonly triggered
by disk-usage-based eviction under disk pressure.
We don't want that to happen for the legitimate evictions of the tenant
that overrides its eviction_policy.
So, this patch
- moves the setting into TenantConf
- adds test coverage
- updates the staging & prod yamls
Forward Compatibility:
Software before this patch will ignore the new tenant conf field and use
the global one instead.
So we can roll back safely.
Backward Compatibility:
Parsing old configs with software as of this patch will fail in
`PageServerConf::parse_and_validate` with error
`unrecognized pageserver option 'evictions_low_residence_duration_metric_threshold'`
if the option is still present in the global section.
We deal with this by updating the configs in Ansible.
fixes https://github.com/neondatabase/neon/issues/3940
Reason and backtrace are added to the Broken state. Backtrace is automatically collected when tenant entered the broken state. The format for API, CLI and metrics is changed and unified to return tenant state name in camel case. Previously snake case was used for metrics and camel case was used for everything else. Now tenant state field in TenantInfo swagger spec is changed to contain state name in "slug" field and other fields (currently only reason and backtrace for Broken variant in "data" field). To allow for this breaking change state was removed from TenantInfo swagger spec because it was not used anywhere.
Please note that the tenant's broken reason is not persisted on disk so the reason is lost when pageserver is restarted.
Requires changes to grafana dashboard that monitors tenant states.
Closes#3001
---------
Co-authored-by: theirix <theirix@gmail.com>
## Describe your changes
## Issue ticket number and link
#3673
## 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.
---------
Co-authored-by: Heikki Linnakangas <heikki@neon.tech>
All non-trivial updates extracted into separate commits, also `carho
hakari` data and its manifest format were updated.
3 sets of crates remain unupdated:
* `base64` — touches proxy in a lot of places and changed its api (by
0.21 version) quite strongly since our version (0.13).
* `opentelemetry` and `opentelemetry-*` crates
```
error[E0308]: mismatched types
--> libs/tracing-utils/src/http.rs:65:21
|
65 | span.set_parent(parent_ctx);
| ---------- ^^^^^^^^^^ expected struct `opentelemetry_api::context::Context`, found struct `opentelemetry::Context`
| |
| arguments to this method are incorrect
|
= note: struct `opentelemetry::Context` and struct `opentelemetry_api::context::Context` have similar names, but are actually distinct types
note: struct `opentelemetry::Context` is defined in crate `opentelemetry_api`
--> /Users/someonetoignore/.cargo/registry/src/github.com-1ecc6299db9ec823/opentelemetry_api-0.19.0/src/context.rs:77:1
|
77 | pub struct Context {
| ^^^^^^^^^^^^^^^^^^
note: struct `opentelemetry_api::context::Context` is defined in crate `opentelemetry_api`
--> /Users/someonetoignore/.cargo/registry/src/github.com-1ecc6299db9ec823/opentelemetry_api-0.18.0/src/context.rs:77:1
|
77 | pub struct Context {
| ^^^^^^^^^^^^^^^^^^
= note: perhaps two different versions of crate `opentelemetry_api` are being used?
note: associated function defined here
--> /Users/someonetoignore/.cargo/registry/src/github.com-1ecc6299db9ec823/tracing-opentelemetry-0.18.0/src/span_ext.rs:43:8
|
43 | fn set_parent(&self, cx: Context);
| ^^^^^^^^^^
For more information about this error, try `rustc --explain E0308`.
error: could not compile `tracing-utils` due to previous error
warning: build failed, waiting for other jobs to finish...
error: could not compile `tracing-utils` due to previous error
```
`tracing-opentelemetry` of version `0.19` is not yet released, that is
supposed to have the update we need.
* similarly, `rustls`, `tokio-rustls`, `rustls-*` and `tls-listener`
crates have similar issue:
```
error[E0308]: mismatched types
--> libs/postgres_backend/tests/simple_select.rs:112:78
|
112 | let mut make_tls_connect = tokio_postgres_rustls::MakeRustlsConnect::new(client_cfg);
| --------------------------------------------- ^^^^^^^^^^ expected struct `rustls::client::client_conn::ClientConfig`, found struct `ClientConfig`
| |
| arguments to this function are incorrect
|
= note: struct `ClientConfig` and struct `rustls::client::client_conn::ClientConfig` have similar names, but are actually distinct types
note: struct `ClientConfig` is defined in crate `rustls`
--> /Users/someonetoignore/.cargo/registry/src/github.com-1ecc6299db9ec823/rustls-0.21.0/src/client/client_conn.rs:125:1
|
125 | pub struct ClientConfig {
| ^^^^^^^^^^^^^^^^^^^^^^^
note: struct `rustls::client::client_conn::ClientConfig` is defined in crate `rustls`
--> /Users/someonetoignore/.cargo/registry/src/github.com-1ecc6299db9ec823/rustls-0.20.8/src/client/client_conn.rs:91:1
|
91 | pub struct ClientConfig {
| ^^^^^^^^^^^^^^^^^^^^^^^
= note: perhaps two different versions of crate `rustls` are being used?
note: associated function defined here
--> /Users/someonetoignore/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-postgres-rustls-0.9.0/src/lib.rs:23:12
|
23 | pub fn new(config: ClientConfig) -> Self {
| ^^^
For more information about this error, try `rustc --explain E0308`.
error: could not compile `postgres_backend` due to previous error
warning: build failed, waiting for other jobs to finish...
```
* aws crates: I could not make new API to work with bucket endpoint
overload, and console e2e tests failed.
Other our tests passed, further investigation is worth to be done in
https://github.com/neondatabase/neon/issues/4008
The PR changes module function-based walreceiver interface with a
`WalReceiver` struct that exposes a few public methods, `new`, `start`
and `stop` now.
Later, the same struct is planned to be used for getting walreceiver
stats (and, maybe, other extra data) to display during missing wal
errors for https://github.com/neondatabase/neon/issues/2106
Now though, the change required extra logic changes:
* due to the `WalReceiver` struct added, it became easier to pass `ctx`
and later do a `detached_child` instead of
bfee412701/pageserver/src/tenant/timeline.rs (L1379-L1381)
* `WalReceiver::start` which is now the public API to start the
walreceiver, could return an `Err` which now may turn a tenant into
`Broken`, same as the timeline that it tries to load during startup.
* `WalReceiverConf` was added to group walreceiver parameters from
pageserver's tenant config
This patch adds a pageserver-global background loop that evicts layers
in response to a shortage of available bytes in the $repo/tenants
directory's filesystem.
The loop runs periodically at a configurable `period`.
Each loop iteration uses `statvfs` to determine filesystem-level space
usage. It compares the returned usage data against two different types
of thresholds. The iteration tries to evict layers until app-internal
accounting says we should be below the thresholds. We cross-check this
internal accounting with the real world by making another `statvfs` at
the end of the iteration. We're good if that second statvfs shows that
we're _actually_ below the configured thresholds. If we're still above
one or more thresholds, we emit a warning log message, leaving it to the
operator to investigate further.
There are two thresholds:
- `max_usage_pct` is the relative available space, expressed in percent
of the total filesystem space. If the actual usage is higher, the
threshold is exceeded.
- `min_avail_bytes` is the absolute available space in bytes. If the
actual usage is lower, the threshold is exceeded.
The iteration evicts layers in LRU fashion with a reservation of up to
`tenant_min_resident_size` bytes of the most recent layers per tenant.
The layers not part of the per-tenant reservation are evicted
least-recently-used first until we're below all thresholds. The
`tenant_min_resident_size` can be overridden per tenant as
`min_resident_size_override` (bytes).
In addition to the loop, there is also an HTTP endpoint to perform one
loop iteration synchronous to the request. The endpoint takes an
absolute number of bytes that the iteration needs to evict before
pressure is relieved. The tests use this endpoint, which is a great
simplification over setting up loopback-mounts in the tests, which would
be required to test the statvfs part of the implementation. We will rely
on manual testing in staging to test the statvfs parts.
The HTTP endpoint is also handy in emergencies where an operator wants
the pageserver to evict a given amount of space _now. Hence, it's
arguments documented in openapi_spec.yml. The response type isn't
documented though because we don't consider it stable. The endpoint
should _not_ be used by Console but it could be used by on-call.
Co-authored-by: Joonas Koivunen <joonas@neon.tech>
Co-authored-by: Dmitry Rodionov <dmitry@neon.tech>
Co-authored-by: Heikki Linnakangas <heikki@neon.tech>
As of #3867, we do artificial layer accesses to layers that will be
needed after the next restart, but not until then because of caches.
With this patch, we also do that for the accesses that the synthetic
size calculation worker does if consumption metrics are enabled.
The actual size calculation is not of importance, but we need to
calculate all of the sizes, so we only call tenant::size::gather_inputs.
Co-authored-by: Christian Schwarz <christian@neon.tech>
There was a warning for trailing garbage after end-of-tar archive, but
it didn't always work. The reason is that we created a StreamReader
over the original copyin-stream, but performed the check for garbage
on the copyin-stream. There could be some garbage bytes buffered in
the StreamReader, which were not caught by the warning.
I considered turning the the warning into a fatal error, aborting the
import, but I wasn't sure if we handle aborting the import properly.
Do we clean up the timeline directory on error? If we don't, we should
make that more robust, but that's a different story.
Also, normally a valid tar archive ends with two 512-byte blocks of zeros.
The tokio_tar crate stops at the first all-zeros block. Read and check
the second all-zeros block, and error out if it's not there, or contains
something unexpected.
- handle automatically fixable future clippies
- tune run-clippy.sh to remove macos specifics which we no longer have
Co-authored-by: Alexander Bayandin <alexander@neon.tech>
Refactor the tenant_size_model code. Segment now contains just the
minimum amount of information needed to calculate the size. Other
information that is useful for building up the segment tree, and for
display purposes, is now kept elsewhere. The code in 'main.rs' has a new
ScenarioBuilder struct for that.
Calculating which Segments are "needed" is now the responsibility of the
caller of tenant_size_mode, not part of the calculation itself. So it's
up to the caller to make all the decisions with retention periods for
each branch.
The output of the sizing calculation is now a Vec of SizeResults, rather
than a tree. It uses a tree representation internally, when doing the
calculation, but it's not exposed to the caller anymore.
Refactor the way the recursive calculation is performed.
Rewrite the code in size.rs that builds the Segment model. Get rid of
the intermediate representation with Update structs. Build the Segments
directly, with some local HashMaps and Vecs to track branch points to
help with that.
retention_period is now an input to gather_inputs(), rather than an
output.
Update pageserver http API: rename /size endpoint to /synthetic_size
with following parameters:
- /synthetic_size?inputs_only to get debug info;
- /synthetic_size?retention_period=0 to override cutoff that is used to
calculate the size;
pass header -H "Accept: text/html" to get HTML output, otherwise JSON is
returned
Update python tests and openapi spec.
---------
Co-authored-by: Anastasia Lubennikova <anastasia@neon.tech>
Co-authored-by: Joonas Koivunen <joonas@neon.tech>
This patch adds a per-timeline periodic task that executes an eviction
policy. The eviction policy is configurable per tenant.
Two policies exist:
- NoEviction (the default one)
- LayerAccessThreshold
The LayerAccessThreshold policy examines the last access timestamp per
layer in the layer map and evicts the layer if that last access is
further in the past than a configurable threshold value.
This policy kind is evaluated periodically at a configurable period.
It logs a summary statistic at `info!()` or `warn!()` level, depending
on whether any evictions failed.
This feature has no explicit killswitch since it's off by default.
## Describe your changes
Expose the currently calculated synthetic size as a Prometheus metric
## Issue ticket number and link
#3509
## Checklist before requesting a review
- [X] 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.
The PR adds an endpoint to show tenant's current config: `GET
/v1/tenant/:tenant_id/config`
Tenant's config consists of two parts: tenant overrides (could be
changed via other management API requests) and the default part,
substituting all missing overrides (constant, hardcoded in pageserver).
The API returns the custom overrides and the final tenant config, after
applying all the defaults.
Along the way, it had to fix two things in the config:
* allow to shorten the json version and omit all `null`'s (same as toml
serializer behaves by default), and to understand such shortened format
when deserialized. A unit test is added
* fix a bug, when `PUT /v1/tenant/config` endpoint rewritten the local
file with what had came in the request, but updating (not rewriting the
old values) the in-memory state instead.
That got uncovered during adjusting the e2e test and fixed to do the
replacement everywhere, otherwise there's no way to revert existing
overrides. Fixes#3471 (commit
dc688affe8)
* fixes https://github.com/neondatabase/neon/issues/3472 by reordering
the config saving operations
Related to: https://github.com/neondatabase/neon/issues/2848
`pageserver_storage_operations_seconds` is the most expensive metric we
have, as there are a lot of tenants/timelines and the histogram had 42
buckets. These are quite sparse too, so instead of having a histogram
per timeline, create a new histogram
`pageserver_storage_operations_seconds_global` without tenant and
timeline dimensions and replace `pageserver_storage_operations_seconds`
with sum and counter.
Co-authored-by: Joonas Koivunen <joonas@neon.tech>
## Describe your changes
Added a metric that allow to monitor tenants state
## Issue ticket number and link
https://github.com/neondatabase/neon/issues/3161
## Checklist before requesting a review
- [X] I have performed a self-review of my code.
- [X] I have added an e2e test for it.
- [ ] 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.
Currently `attach` doesn't write a tenant config, because we don't back
it up in the first place. The current implementation of
`Tenant::persist_tenant_config` does not allow changing tenant's
configuration through the http api which will fail because the file
wasn't created on attach and
`OpenOptions::truncate(true).write(true).create_new(false)` is used.
I think this patch allows for least controversial middle ground which
*enables* changing tenant configuration even for attached tenants (not
just created tenants).
Change the signature so that it takes an Arc<Timeline> reference to the
source timeline, instead of just the ID. All the callers have an Arc
reference at hand, so this is more convenient for everyone.
Reorder the code a bit and improve the comments, to make it more clear
what it does and why.
Motivation
==========
Layer Eviction Needs Context
----------------------------
Before we start implementing layer eviction, we need to collect some
access statistics per layer file or maybe even page.
Part of these statistics should be the initiator of a page read request
to answer the question of whether it was page_service vs. one of the
background loops, and if the latter, which of them?
Further, it would be nice to learn more about what activity in the pageserver
initiated an on-demand download of a layer file.
We will use this information to test out layer eviction policies.
Read more about the current plan for layer eviction here:
https://github.com/neondatabase/neon/issues/2476#issuecomment-1370822104
task_mgr problems + cancellation + tenant/timeline lifecycle
------------------------------------------------------------
Apart from layer eviction, we have long-standing problems with task_mgr,
task cancellation, and various races around tenant / timeline lifecycle
transitions.
One approach to solve these is to abandon task_mgr in favor of a
mechanism similar to Golang's context.Context, albeit extended to
support waiting for completion, and specialized to the needs in the
pageserver.
Heikki solves all of the above at once in PR
https://github.com/neondatabase/neon/pull/3228 , which is not yet
merged at the time of writing.
What Is This Patch About
========================
This patch addresses the immediate needs of layer eviction by
introducing a `RequestContext` structure that is plumbed through the
pageserver - all the way from the various entrypoints (page_service,
management API, tenant background loops) down to
Timeline::{get,get_reconstruct_data}.
The struct carries a description of the kind of activity that initiated
the call. We re-use task_mgr::TaskKind for this.
Also, it carries the desired on-demand download behavior of the entrypoint.
Timeline::get_reconstruct_data can then log the TaskKind that initiated
the on-demand download.
I developed this patch by git-checking-out Heikki's big RequestContext
PR https://github.com/neondatabase/neon/pull/3228 , then deleting all
the functionality that we do not need to address the needs for layer
eviction.
After that, I added a few things on top:
1. The concept of attached_child and detached_child in preparation for
cancellation signalling through RequestContext, which will be added in
a future patch.
2. A kill switch to turn DownloadBehavior::Error into a warning.
3. Renamed WalReceiverConnection to WalReceiverConnectionPoller and
added an additional TaskKind WalReceiverConnectionHandler.These were
necessary to create proper detached_child-type RequestContexts for the
various tasks that walreceiver starts.
How To Review This Patch
========================
Start your review with the module-level comment in context.rs.
It explains the idea of RequestContext, what parts of it are implemented
in this patch, and the future plans for RequestContext.
Then review the various `task_mgr::spawn` call sites. At each of them,
we should be creating a new detached_child RequestContext.
Then review the (few) RequestContext::attached_child call sites and
ensure that the spawned tasks do not outlive the task that spawns them.
If they do, these call sites should use detached_child() instead.
Then review the todo_child() call sites and judge whether it's worth the
trouble of plumbing through a parent context from the caller(s).
Lastly, go through the bulk of mechanical changes that simply forwards
the &ctx.
Before this patch, when `initialize_with_lock` was called via
`timeline_init_and_sync`, we would transition the timeline like so:
load_local_timeline/load_remote_timeline:
timeline_init_and_sync
Timeline::new
() => Loading
initialize_with_lock:
set_state(Active)
Loading => Active
timeline.activate()
Active => Active
The TimelineState::Suspsended was dubious to begin with. I suppose
that the intention was that timelines could transition back and
forth between Active and Suspended states.
But practically, the code before this patch never did that.
The transitions were:
() ==Timeline::new==> Suspended ==*==> {Active,Broken,Stopping}
One exception: Tenant::set_stopping() could transition timelines like
so:
!Broken ==Tenant::set_stopping()==> Suspended
But Tenant itself cannot transition from stopping state to any other
state.
Thus, this patch removes TimelineState::Suspended and introduces a new
state Loading. The aforementioned transitions change as follows:
- () ==Timeline::new==> Suspended ==*==> {Active,Broken,Stopping}
+ () ==Timeline::new==> Loading ==*==> {Active,Broken,Stopping}
- !Broken ==Tenant::set_stopping()==> Suspended
+ !Broken ==Tenant::set_stopping()==> Stopping
Walreceiver's connection manager loop watches TimelineState to decide
whether it should retry connecting, or exit.
This patch changes the loop to exit when it observes the transition
into Stopping state.
Walreceiver isn't supposed to be started until the timeline transitions
into Active state. So, this patch also adds some warn!() messages
in case this happens anyways.
This reverts commit 826e89b9ce.
The problem with that commit was that it deletes the TempDir while
there are still EphemeralFile instances open.
At first I thought this could be fixed by simply adding
Handle::current().block_on(task_mgr::shutdown(None, Some(tenant_id), None))
to TenantHarness::drop, but it turned out to be insufficient.
So, reverting the commit until we find a proper solution.
refs https://github.com/neondatabase/neon/issues/3385
- handle errors in calculate_synthetic_size_worker. Don't exit the bgworker if one tenant failed.
- add cached_synthetic_tenant_size to cache values calculated by the bgworker
- code cleanup: remove unneeded info! messages, clean comments
- handle collect_metrics_task() error. Don't exit collect_metrics worker if one task failed.
- add unit test to cover case when we have multiple branches at the same lsn
This makes Timeline::get() async, and all functions that call it
directly or indirectly with it. The with_ondemand_download() mechanism
is gone, Timeline::get() now always downloads files, whether you want
it or not. That is what all the current callers want, so even though
this loses the capability to get a page only if it's already in the
pageserver, without downloading, we were not using that capability.
There were some places that used 'no_ondemand_download' in the WAL
ingestion code that would error out if a layer file was not found
locally, but those were dubious. We do actually want to on-demand
download in all of those places.
Per discussion at
https://github.com/neondatabase/neon/pull/3233#issuecomment-1368032358
Before this change, we would not .measure_remote_op for index part
downloads.
And more generally, it's good to pass not just uploads but also
downloads through RemoteTimelineClient, e.g., if we ever want to
implement some timeline-scoped policies there.
Found this while working on https://github.com/neondatabase/neon/pull/3250
where I add a metric to measure the degree of concurrent downloads.
Layer download was missing in a test that I added there.
The synchronous 'tar' crate has required us to use block_in_place and
SyncIoBridge to work together with the async I/O in the client
connection. Switch to 'tokio-tar' crate that uses async I/O natively.
As part of this, move the CopyDataWriter implementation to
postgres_backend_async.rs. Even though it's only used in one place
currently, it's in principle generally applicable whenever you want to
use COPY out.
Unfortunately we cannot use the 'tokio-tar' as it is: the Builder
implementation requires the writer to have 'static lifetime. So we
have to use a modified version without that requirement. The 'static
lifetime was required just for the Drop implementation that writes
the end-of-archive sections if the Builder is dropped without calling
`finish`. But we don't actually want that behavior anyway; in fact
we had to jump through some hoops with the AbortableWrite hack to skip
those. With the modified version of 'tokio-tar' without that Drop
implementation, we don't need AbortableWrite either.
Co-authored-by: Kirill Bulatov <kirill@neon.tech>
1.66 release speeds up compile times for over 10% according to tests.
Also its Clippy finds plenty of old nits in our code:
* useless conversion, `foo as u8` where `foo: u8` and similar, removed
`as u8` and similar
* useless references and dereferenced (that were automatically adjusted
by the compiler), removed various `&` and `*`
* bool -> u8 conversion via `if/else`, changed to `u8::from`
* Map `.iter()` calls where only values were used, changed to
`.values()` instead
Standing out lints:
* `Eq` is missing in our protoc generated structs. Silenced, does not
seem crucial for us.
* `fn default` looks like the one from `Default` trait, so I've
implemented that instead and replaced the `dummy_*` method in tests with
`::default()` invocation
* Clippy detected that
```
if retry_attempt < u32::MAX {
retry_attempt += 1;
}
```
is a saturating add and proposed to replace it.
The code in this change was extracted from #2595 (Heikki’s on-demand
download draft PR).
High-Level Changes
- New RemoteLayer Type
- On-Demand Download As An Effect Of Page Reconstruction
- Breaking Semantics For Physical Size Metrics
There are several follow-up work items planned.
Refer to the Epic issue on GitHub: https://github.com/neondatabase/neon/issues/2029
closes https://github.com/neondatabase/neon/pull/3013
Co-authored-by: Kirill Bulatov <kirill@neon.tech>
Co-authored-by: Christian Schwarz <christian@neon.tech>
New RemoteLayer Type
====================
Instead of downloading all layers during tenant attach, we create
RemoteLayer instances for each of them and add them to the layer map.
On-Demand Download As An Effect Of Page Reconstruction
======================================================
At the heart of pageserver is Timeline::get_reconstruct_data(). It
traverses the layer map until it has collected all the data it needs to
produce the page image. Most code in the code base uses it, though many
layers of indirection.
Before this patch, the function would use synchronous filesystem IO to
load data from disk-resident layer files if the data was not cached.
That is not possible with RemoteLayer, because the layer file has not
been downloaded yet. So, we do the download when get_reconstruct_data
gets there, i.e., “on demand”.
The mechanics of how the download is done are rather involved, because
of the infamous async-sync-async sandwich problem that plagues the async
Rust world. We use the new PageReconstructResult type to work around
this. Its introduction is the cause for a good amount of code churn in
this patch. Refer to the block comment on `with_ondemand_download()`
for details.
Breaking Semantics For Physical Size Metrics
============================================
We rename prometheus metric pageserver_{current,resident}_physical_size to
reflect what this metric actually represents with on-demand download.
This intentionally BREAKS existing grafana dashboard and the cost model data
pipeline. Breaking is desirable because the meaning of this metrics has changed
with on-demand download. See
https://docs.google.com/document/d/12AFpvKY-7FZdR5a4CaD6Ir_rI3QokdCLSPJ6upHxJBo/edit#
for how we will handle this breakage.
Likewise, we rename the new billing_metrics’s PhysicalSize => ResidentSize.
This is not yet used anywhere, so, this is not a breaking change.
There is still a field called TimelineInfo::current_physical_size. It
is now the sum of the layer sizes in layer map, regardless of whether
local or remote. To compute that sum, we added a new trait method
PersistentLayer::file_size().
When updating the Python tests, we got rid of
current_physical_size_non_incremental. An earlier commit removed it from
the OpenAPI spec already, so this is not a breaking change.
test_timeline_size.py has grown additional assertions on the
resident_physical_size metric.
