There was a nominal split between the tests in layered_repository.rs and
repository.rs, such that tests specific to the layered implementation were
supposed to be in layered_repository.rs, and tests that should work with
any implementation of the traits were supposed to be in repository.rs.
In practice, the line was quite muddled. With minor tweaks, many of the
tests in layered_repository.rs should work with other implementations too,
and vice versa. And in practice we only have one implementation, so it's
more straightforward to gather all unit tests in one place.
usize/isize type corresponds to the CPU architecture's pointer width,
i.e. 64 bits on a 64-bit platform and 32 bits on a 32-bit platform.
The logical size of a database has nothing to do with the that, so
u64/i64 is more appropriate.
It doesn't make any difference in practice as long as you're on a
64-bit platform, and it's hard to imagine anyone wanting to run the
pageserver on a 32-bit platform, but let's be tidy.
Also add a comment on why we use signed i64 for the logical size
variable, even though size should never be negative. I'm not sure the
reasons are very good, but at least this documents them, and hints at
some possible better solutions.
- There was an issue with zero commit_lsn `reason: LaggingWal { current_commit_lsn: 0/0, new_commit_lsn: 1/6FD90D38, threshold: 10485760 } }`. The problem was in `send_wal.rs`, where we initialized `end_pos = Lsn(0)` and in some cases sent it to the pageserver.
- IDENTIFY_SYSTEM previously returned `flush_lsn` as a physical end of WAL. Now it returns `flush_lsn` (as it was) to walproposer and `commit_lsn` to everyone else including pageserver.
- There was an issue with backoff where connection was cancelled right after initialization: `connected!` -> `safekeeper_handle_db: Connection cancelled` -> `Backoff: waiting 3 seconds`. The problem was in sleeping before establishing the connection. This is fixed by reworking retry logic.
- There was an issue with getting `NoKeepAlives` reason in a loop. The issue is probably the same as the previous.
- There was an issue with filtering safekeepers based on retry attempts, which could filter some safekeepers indefinetely. This is fixed by using retry cooldown duration instead of retry attempts.
- Some `send_wal.rs` connections failed with errors without context. This is fixed by adding a timeline to safekeepers errors.
New retry logic works like this:
- Every candidate has a `next_retry_at` timestamp and is not considered for connection until that moment
- When walreceiver connection is closed, we update `next_retry_at` using exponential backoff, increasing the cooldown on every disconnect.
- When `last_record_lsn` was advanced using the WAL from the safekeeper, we reset the retry cooldown and exponential backoff, allowing walreceiver to reconnect to the same safekeeper instantly.
Re-export only things that are used by other modules.
In the future, I'm imagining that we run bindgen twice, for Postgres
v14 and v15. The two sets of bindings would go into separate
'bindings_v14' and 'bindings_v15' modules.
Rearrange postgres_ffi modules.
Move function, to avoid Postgres version dependency in timelines.rs
Move function to generate a logical-message WAL record to postgres_ffi.
* Do not create initial tenant and timeline (adjust Python tests for that)
* Rework config handling during init, add --update-config to manage local config updates
This patch makes walreceiver logic more complicated, but it should work better in most cases. Added `test_wal_lagging` to test scenarios where alive safekeepers can lag behind other alive safekeepers.
- There was a bug which looks like `etcd_info.timeline.commit_lsn > Some(self.local_timeline.get_last_record_lsn())` filtered all safekeepers in some strange cases. I removed this filter, it should probably help with #2237
- Now walreceiver_connection reports status, including commit_lsn. This allows keeping safekeeper connection even when etcd is down.
- Safekeeper connection now fails if pageserver doesn't receive safekeeper messages for some time. Usually safekeeper sends messages at least once per second.
- `LaggingWal` check now uses `commit_lsn` directly from safekeeper. This fixes the issue with often reconnects, when compute generates WAL really fast.
- `NoWalTimeout` is rewritten to trigger only when we know about the new WAL and the connected safekeeper doesn't stream any WAL. This allows setting a small `lagging_wal_timeout` because it will trigger only when we observe that the connected safekeeper has stuck.
Resolves#2097
- use timeline modification's `lsn` and timeline's `last_record_lsn` to determine the corresponding LSN to query data in `DatadirModification::get`
- update `test_import_from_pageserver`. Split the test into 2 variants: `small` and `multisegment`.
+ `small` is the old test
+ `multisegment` is to simulate #2097 by using a larger number of inserted rows to create multiple segment files of a relation. `multisegment` is configured to only run with a `release` build
To flush inmemory layer eventually when no new data arrives, which helps
safekeepers to suspend activity (stop pushing to the broker). Default 10m should
be ok.
Move all the fields that were returned by the wal_receiver endpoint into
timeline_detail. Internally, move those fields from the separate global
WAL_RECEIVERS hash into the LayeredTimeline struct. That way, all the
information about a timeline is kept in one place.
In the passing, I noted that the 'thread_id' field was removed from
WalReceiverEntry in commit e5cb727572, but it forgot to update
openapi_spec.yml. This commit removes that too.
What the WAL receiver really connects to is the safekeeper. The
"producer" term is a bit misleading, as the safekeeper doesn't produce
the WAL, the compute node does.
This change also applies to the name of the field used in the mgmt API
in in the response of the
'/v1/tenant/:tenant_id/timeline/:timeline_id/wal_receiver' endpoint.
AFAICS that's not used anywhere else than one python test, so it
should be OK to change it.
Ref #1902.
- Track the layered timeline's `physical_size` using `pageserver_current_physical_size` metric when updating the layer map.
- Report the local timeline's `physical_size` in timeline GET APIs.
- Add `include-non-incremental-physical-size` URL flag to also report the local timeline's `physical_size_non_incremental` (similar to `logical_size_non_incremental`)
- Add a `UIntGaugeVec` and `UIntGauge` to represent `u64` prometheus metrics
Co-authored-by: Dmitry Rodionov <dmitry@neon.tech>
Previously DatadirTimeline was a separate struct, and there was a 1:1
relationship between each DatadirTimeline and LayeredTimeline. That was
a bit awkward; whenever you created a timeline, you also needed to create
the DatadirTimeline wrapper around it, and if you only had a reference
to the LayeredTimeline, you would need to look up the corresponding
DatadirTimeline struct through tenant_mgr::get_local_timeline_with_load().
There were a couple of calls like that from LayeredTimeline itself.
Refactor DatadirTimeline, so that it's a trait, and mark LayeredTimeline
as implementing that trait. That way, there's only one object,
LayeredTimeline, and you can call both Timeline and DatadirTimeline
functions on that. You can now also call DatadirTimeline functions from
LayeredTimeline itself.
I considered just moving all the functions from DatadirTimeline directly
to Timeline/LayeredTimeline, but I still like to have some separation.
Timeline provides a simple key-value API, and handles durably storing
key/value pairs, and branching. Whereas DatadirTimeline is stateless, and
provides an abstraction over the key-value store, to present an interface
with relations, databases, etc. Postgres concepts.
This simplified the logical size calculation fast-path for branch
creation, introduced in commit 28243d68e6. LayerTimeline can now
access the ancestor's logical size directly, so it doesn't need the
caller to pass it to it. I moved the fast-path to init_logical_size()
function itself. It now checks if the ancestor's last LSN is the same
as the branch point, i.e. if there haven't been any changes on the
ancestor after the branch, and copies the size from there. An
additional bonus is that the optimization will now work any time you
have a branch of another branch, with no changes from the ancestor,
not only at a create-branch command.
The layered_repository.rs file had grown to be very large. Split off
the LayeredTimeline struct and related code to a separate source file to
make it more manageable.
There are plans to move much of the code to track timelines from
tenant_mgr.rs to LayeredRepository. That will make layered_repository.rs
grow again, so now is a good time to split it.
There's a lot more cleanup to do, but this commit intentionally only
moves existing code and avoids doing anything else, for easier review.
## Overview
This patch reduces the number of memory allocations when running the page server under a heavy write workload. This mostly helps improve the speed of WAL record ingestion.
## Changes
- modified `DatadirModification` to allow reuse the struct's allocated memory after each modification
- modified `decode_wal_record` to allow passing a `DecodedWALRecord` reference. This helps reuse the struct in each `decode_wal_record` call
- added a reusable buffer for serializing object inside the `InMemoryLayer::put_value` function
- added a performance test simulating a heavy write workload for testing the changes in this patch
### Semi-related changes
- remove redundant serializations when calling `DeltaLayer::put_value` during `InMemoryLayer::write_to_disk` function call [1]
- removed the info span `info_span!("processing record", lsn = %lsn)` during each WAL ingestion [2]
## Notes
- [1]: in `InMemoryLayer::write_to_disk`, a deserialization is called
```
let val = Value::des(&buf)?;
delta_layer_writer.put_value(key, *lsn, val)?;
```
`DeltaLayer::put_value` then creates a serialization based on the previous deserialization
```
let off = self.blob_writer.write_blob(&Value::ser(&val)?)?;
```
- [2]: related: https://github.com/neondatabase/neon/issues/733
* More precisely control size of inmem layer
* Force recompaction of L0 layers if them contains large non-wallogged BLOBs to avoid too large layers
* Add modified version of test_hot_update test (test_dup_key.py) which should generate large layers without large number of tables
* Change test name in test_dup_key
* Add Layer::get_max_key_range function
* Add layer::key_iter method and implement new approach of splitting layers during compaction based on total size of all key values
* Add test_large_schema test for checking layer file size after compaction
* Make clippy happy
* Restore checking LSN distance threshold for checkpoint in-memory layer
* Optimize stoage keys iterator
* Update pageserver/src/layered_repository.rs
Co-authored-by: Heikki Linnakangas <heikki@zenith.tech>
* Update pageserver/src/layered_repository.rs
Co-authored-by: Heikki Linnakangas <heikki@zenith.tech>
* Update pageserver/src/layered_repository.rs
Co-authored-by: Heikki Linnakangas <heikki@zenith.tech>
* Update pageserver/src/layered_repository.rs
Co-authored-by: Heikki Linnakangas <heikki@zenith.tech>
* Update pageserver/src/layered_repository.rs
Co-authored-by: Heikki Linnakangas <heikki@zenith.tech>
* Fix code style
* Reduce number of tables in test_large_schema to make it fit in timeout with debug build
* Fix style of test_large_schema.py
* Fix handlng of duplicates layers
Co-authored-by: Heikki Linnakangas <heikki@zenith.tech>
Resolves#2054
**Context**: branch creation needs to wait for GC to acquire `gc_cs` lock, which prevents creating new timelines during GC. However, because individual timeline GC iteration also requires `compaction_cs` lock, branch creation may also need to wait for compactions of multiple timelines. This results in large latency when creating a new branch, which we advertised as *"instantly"*.
This PR optimizes the latency of branch creation by separating GC into two phases:
1. Collect GC data (branching points, cutoff LSNs, etc)
2. Perform GC for each timeline
The GC bottleneck comes from step 2, which must wait for compaction of multiple timelines. This PR modifies the branch creation and GC functions to allow GC to hold the GC lock only in step 1. As a result, branch creation doesn't need to wait for compaction to finish but only needs to wait for GC data collection step, which is fast.
Reorganize existing READMEs and other documentation files into mdbook
format. The resulting Table of Contents is a mix of placeholders for
docs that we should write, and documentation files that we already had,
dropped into the most appropriate place.
Update the Pageserver overview diagram. Add sections on thread
management and WAL redo processes.
Add all the RFCs to the mdbook Table of Content too.
Per github issue #1979
