## Problem
After a shard split, the pageserver leaves the ancestor shard's content
in place. It may be referenced by child shards, but eventually child
shards will de-reference most ancestor layers as they write their own
data and do GC. We would like to eventually clean up those ancestor
layers to reclaim space.
## Summary of changes
- Extend the physical GC command with `--mode=full`, which includes
cleaning up unreferenced ancestor shard layers
- Add test `test_scrubber_physical_gc_ancestors`
- Remove colored log output: in testing this is irritating ANSI code
spam in logs, and in interactive use doesn't add much.
- Refactor storage controller API client code out of storcon_client into
a `storage_controller/client` crate
- During physical GC of ancestors, call into the storage controller to
check that the latest shards seen in S3 reflect the latest state of the
tenant, and there is no shard split in progress.
Successor of #8288 , just enable zstd in tests. Also adds a test that
creates easily compressable data.
Part of #5431
---------
Co-authored-by: John Spray <john@neon.tech>
Co-authored-by: Joonas Koivunen <joonas@neon.tech>
## Problem
Ahead of enabling eviction in the field, where it will become the
normal/default mode, let's enable it by default throughout our tests in
case any issues become visible there.
## Summary of changes
- Make default `extra_opts` for safekeepers enable offload & deletion
- Set low timeouts in `extra_opts` so that tests running for tens of
seconds have a chance to hit some of these background operations.
When `NeonEnv.from_repo_dir` was introduced, storage controller stored
its
state exclusively `attachments.json`.
Since then, it has moved to using Postgres, which stores its state in
`storage_controller_db`.
But `NeonEnv.from_repo_dir` wasn't adjusted to do this.
This PR rectifies the situation.
Context for this is failures in
`test_pageserver_characterize_throughput_with_n_tenants`
CF:
https://neondb.slack.com/archives/C033RQ5SPDH/p1721035799502239?thread_ts=1720901332.293769&cid=C033RQ5SPDH
Notably, `from_repo_dir` is also used by the backwards- and
forwards-compatibility.
Thus, the changes in this PR affect those tests as well.
However, it turns out that the compatibility snapshot already contains
the `storage_controller_db`.
Thus, it should just work and in fact we can remove hacks like
`fixup_storage_controller`.
Follow-ups created as part of this work:
* https://github.com/neondatabase/neon/issues/8399
* https://github.com/neondatabase/neon/issues/8400
## Problem
We lack insight into:
- How much of a tenant's physical size is image vs. delta layers
- Average sizes of image vs. delta layers
- Total layer counts per timeline, indicating size of index_part object
As well as general observability love, this is motivated by
https://github.com/neondatabase/neon/issues/6738, where we need to
define some sensible thresholds for storage amplification, and using
total physical size may not work well (if someone does a lot of DROPs
then it's legitimate for the physical-synthetic ratio to be huge), but
the ratio between image layer size and delta layer size may be a better
indicator of whether we're generating unreasonable quantities of image
layers.
## Summary of changes
- Add pageserver_layer_bytes and pageserver_layer_count metrics,
labelled by timeline and `kind` (delta or image)
- Add & subtract these with LayerInner's lifetime.
I'm intentionally avoiding using a generic metric RAII guard object, to
avoid bloating LayerInner: it already has all the information it needs
to update metric on new+drop.
This test reproduces the case of a writer creating a deep stack of L0
layers. It uses realistic layer sizes and writes several gigabytes of
data, therefore runs as a performance test although it is validating
memory footprint rather than performance per se.
It acts a regression test for two recent fixes:
- https://github.com/neondatabase/neon/pull/8401
- https://github.com/neondatabase/neon/pull/8391
In future it will demonstrate the larger improvement of using a k-merge
iterator for L0 compaction (#8184)
This test can be extended to enforce limits on the memory consumption of
other housekeeping steps, by restarting the pageserver and then running
other things to do the same "how much did RSS increase" measurement.
As described in #8385, the likely source for flakiness in
test_tenant_creation_fails is the following sequence of events:
1. test instructs the storage controller to create the tenant
2. storage controller adds the tenant and persists it to the database.
issues a creation request
3. the pageserver restarts with the failpoint disabled
4. storage controller's background reconciliation still wants to create
the tenant
5. pageserver gets new request to create the tenant from background
reconciliation
This commit just avoids the storage controller entirely. It has its own
set of issues, as the re-attach request will obviously not include the
tenant, but it's still useful to test for non-existence of the tenant.
The generation is also not optional any more during tenant attachment.
If you omit it, the pageserver yields an error. We change the signature
of `tenant_attach` to reflect that.
Alternative to #8385Fixes#8266
Right now timeline detach ancestor reports an error (409, "no ancestor")
on a new attempt after successful completion. This makes it troublesome
for storage controller retries. Fix it to respond with `200 OK` as if
the operation had just completed quickly.
Additionally, the returned timeline identifiers in the 200 OK response
are now ordered so that responses between different nodes for error
comparison are done by the storage controller added in #8353.
Design-wise, this PR introduces a new strategy for accessing the latest
uploaded IndexPart:
`RemoteTimelineClient::initialized_upload_queue(&self) ->
Result<UploadQueueAccessor<'_>, NotInitialized>`. It should be a more
scalable way to query the latest uploaded `IndexPart` than to add a
query method for each question directly on `RemoteTimelineClient`.
GC blocking will need to be introduced to make the operation fully
idempotent. However, it is idempotent for the cases demonstrated by
tests.
Cc: #6994
Currently storage controller does not support forwarding timeline detach
ancestor requests to pageservers. Add support for forwarding `PUT
.../:tenant_id/timelines/:timeline_id/detach_ancestor`. Implement the
support mostly as is, because the timeline detach ancestor will be made
(mostly) idempotent in future PR.
Cc: #6994
## Problem
In anticipation of later adding a really nice drain+delete API, I
initially only added an intentionally basic `/drop` API that is just
about usable for deleting nodes in a pinch, but requires some ugly
storage controller restarts to persuade it to restart secondaries.
## Summary of changes
I started making a few tiny fixes, and ended up writing the delete
API...
- Quality of life nit: ordering of node + tenant listings in storcon_cli
- Papercut: Fix the attach_hook using the wrong operation type for
reporting slow locks
- Make Service::spawn tolerate `generation_pageserver` columns that
point to nonexistent node IDs. I started out thinking of this as a
general resilience thing, but when implementing the delete API I
realized it was actually a legitimate end state after the delete API is
called (as that API doesn't wait for all reconciles to succeed).
- Add a `DELETE` API for nodes, which does not gracefully drain, but
does reschedule everything. This becomes safe to use when the system is
in any state, but will incur availability gaps for any tenants that
weren't already live-migrated away. If tenants have already been
drained, this becomes a totally clean + safe way to decom a node.
- Add a test and a storcon_cli wrapper for it
This is meant to be a robust initial API that lets us remove nodes
without doing ugly things like restarting the storage controller -- it's
not quite a totally graceful node-draining routine yet. There's more
work in https://github.com/neondatabase/neon/issues/8333 to get to our
end-end state.
## Problem
Follow up to https://github.com/neondatabase/neon/pull/8335, to improve
observability of how many evict/restores we are doing.
## Summary of changes
- Add `safekeeper_eviction_events_started_total` and
`safekeeper_eviction_events_completed_total`, with a "kind" label of
evict or restore. This gives us rates, and also ability to calculate how
many are in progress.
- Generalize SafekeeperMetrics test type to use the same helpers as
pageserver, and enable querying any metric.
- Read the new metrics at the end of the eviction test.
`trace_read_requests` is a per `Tenant`-object option.
But the `handle_pagerequests` loop doesn't know which
`Tenant` object (i.e., which shard) the request is for.
The remaining use of the `Tenant` object is to check `tenant.cancel`.
That check is incorrect [if the pageserver hosts multiple
shards](https://github.com/neondatabase/neon/issues/7427#issuecomment-2220577518).
I'll fix that in a future PR where I completely eliminate the holding
of `Tenant/Timeline` objects across requests.
See [my code RFC](https://github.com/neondatabase/neon/pull/8286) for
the
high level idea.
Note that we can always bring the tracing functionality if we need it.
But since it's actually about logging the `page_service` wire bytes,
it should be a `page_service`-level config option, not per-Tenant.
And for enabling tracing on a single connection, we can implement
a `set pageserver_trace_connection;` option.
## Problem
- The condition for eviction is not time-based: it is possible for a
timeline to be restored in response to a client, that client times out,
and then as soon as the timeline is restored it is immediately evicted
again.
- There is no delay on eviction at startup of the safekeeper, so when it
starts up and sees many idle timelines, it does many evictions which
will likely be immediately restored when someone uses the timeline.
## Summary of changes
- Add `eviction_min_resident` parameter, and use it in
`ready_for_eviction` to avoid evictions if the timeline has been
resident for less than this period.
- This also implicitly delays evictions at startup for
`eviction_min_resident`
- Set this to a very low number for the existing eviction test, which
expects immediate eviction.
The default period is 15 minutes. The general reasoning for that is that
in the worst case where we thrash ~10k timelines on one safekeeper,
downloading 16MB for each one, we should set a period that would not
overwhelm the node's bandwidth.
Allows a process to run without blocking program execution, which can be
useful for certain test scenarios.
Co-authored-by: Sasha Krassovsky <sasha@neon.tech>
## Problem
We want to be able to test how our infrastructure reacts on segfaults in
Postgres (for example, we collect cores, and get some required
logs/metrics, etc)
## Summary of changes
- Add `trigger_segfauls` function to `neon_test_utils` to trigger a
segfault in Postgres
- Add `trigger_panic` function to `neon_test_utils` to trigger SIGABRT
(by using `elog(PANIC, ...))
- Fix cleanup logic in regression tests in endpoint crashed
Part of #7497, closes#8071. (accidentally closed#8208, reopened here)
## Problem
After the changes in #8084, we need synthetic size to also account for
leased LSNs so that users do not get free retention by running a small
ephemeral endpoint for a long time.
## Summary of changes
This PR integrates LSN leases into the synthetic size calculation. We
model leases as read-only branches started at the leased LSN (except it
does not have a timeline id).
Other changes:
- Add new unit tests testing whether a lease behaves like a read-only
branch.
- Change `/size_debug` response to include lease point in the SVG
visualization.
- Fix `/lsn_lease` HTTP API to do proper parsing for POST.
Signed-off-by: Yuchen Liang <yuchen@neon.tech>
Co-authored-by: Joonas Koivunen <joonas@neon.tech>
Co-authored-by: Christian Schwarz <christian@neon.tech>
## Problem
When generations were new, these messages were an important way of
noticing if something unexpected was going on. We found some real issues
when investigating tests that unexpectedly tripped them.
At time has gone on, this code is now pretty battle-tested, and as we do
more live migrations etc, it's fairly normal to see the occasional
message from a node with a stale generation.
At this point the cognitive load on developers to selectively allow-list
these logs outweighs the benefit of having them at warn severity.
Closes: https://github.com/neondatabase/neon/issues/8080
## Summary of changes
- Downgrade "Dropped remote consistent LSN updates" and "Dropping stale
deletions" messages to INFO
- Remove all the allow-list entries for these logs.
## Problem
The metrics we have today aren't convenient for planning around the
impact of timeline archival on costs.
Closes: https://github.com/neondatabase/neon/issues/8108
## Summary of changes
- Add metric `pageserver_archive_size`, which indicates the logical
bytes of data which we would expect to write into an archived branch.
- Add metric `pageserver_pitr_history_size`, which indicates the
distance between last_record_lsn and the PITR cutoff.
These metrics are somewhat temporary: when we implement #8088 and
associated consumption metric changes, these will reach a final form.
For now, an "archived" branch is just any branch outside of its parent's
PITR window: later, archival will become an explicit state (which will
_usually_ correspond to falling outside the parent's PITR window).
The overall volume of timeline metrics is something to watch, but we are
removing many more in https://github.com/neondatabase/neon/pull/8245
than this PR is adding.
Before this PR, `RemoteStorageConfig::from_toml` would support
deserializing an
empty `{}` TOML inline table to a `None`, otherwise try `Some()`.
We can instead let
* in proxy: let clap derive handle the Option
* in PS & SK: assume that if the field is specified, it must be a valid
RemtoeStorageConfig
(This PR started with a much simpler goal of factoring out the
`deserialize_item` function because I need that in another PR).
We have one pretty serious MVCC visibility bug with hot standby
replicas. We incorrectly treat any transactions that are in progress
in the primary, when the standby is started, as aborted. That can
break MVCC for queries running concurrently in the standby. It can
also lead to hint bits being set incorrectly, and that damage can last
until the replica is restarted.
The fundamental bug was that we treated any replica start as starting
from a shut down server. The fix for that is straightforward: we need
to set 'wasShutdown = false' in InitWalRecovery() (see changes in the
postgres repo).
However, that introduces a new problem: with wasShutdown = false, the
standby will not open up for queries until it receives a running-xacts
WAL record from the primary. That's correct, and that's how Postgres
hot standby always works. But it's a problem for Neon, because:
* It changes the historical behavior for existing users. Currently,
the standby immediately opens up for queries, so if they now need to
wait, we can breka existing use cases that were working fine
(assuming you don't hit the MVCC issues).
* The problem is much worse for Neon than it is for standalone
PostgreSQL, because in Neon, we can start a replica from an
arbitrary LSN. In standalone PostgreSQL, the replica always starts
WAL replay from a checkpoint record, and the primary arranges things
so that there is always a running-xacts record soon after each
checkpoint record. You can still hit this issue with PostgreSQL if
you have a transaction with lots of subtransactions running in the
primary, but it's pretty rare in practice.
To mitigate that, we introduce another way to collect the
running-xacts information at startup, without waiting for the
running-xacts WAL record: We can the CLOG for XIDs that haven't been
marked as committed or aborted. It has limitations with
subtransactions too, but should mitigate the problem for most users.
See https://github.com/neondatabase/neon/issues/7236.
Co-authored-by: Konstantin Knizhnik <knizhnik@neon.tech>
The 'running' boolean was replaced with a semaphore in commit
f0e2bb79b2, but this initialization was missed. Remove it so that if a
test tries to access it, you get an error rather than always claiming
that the endpoint is not running.
Spotted by Arseny at
https://github.com/neondatabase/neon/pull/7288#discussion_r1660068657
## Problem
For some time, we have created tenants with calls to location_conf. The
legacy "POST /v1/tenant" path was only used in some tests.
## Summary of changes
- Remove the API
- Relocate TenantCreateRequest to the controller API file (this used to
be used in both pageserver and controller APIs)
- Rewrite tenant_create test helper to use location_config API, as
control plane and storage controller do
- Update docker-compose test script to create tenants with
location_config API (this small commit is also present in
https://github.com/neondatabase/neon/pull/7947)
- Add --safekeepers option to neon_local reconfigure
- Add it to python Endpoint reconfigure
- Implement config reload in walproposer by restarting the whole bgw when
safekeeper list changes.
ref https://github.com/neondatabase/neon/issues/6341
Also, modify the "neon_local timeline import" command so that it
doesn't create the endpoint any more. I don't see any reason to bundle
that in the same command, the "timeline create" and "timeline branch"
commands don't do that either.
I plan to add more tests similar to 'test_import_at_2bil', this will
help to reduce the copy-pasting.
Fixes https://github.com/neondatabase/neon/issues/6337
Add safekeeper support to switch between `Present` and
`Offloaded(flush_lsn)` states. The offloading is disabled by default,
but can be controlled using new cmdline arguments:
```
--enable-offload
Enable automatic switching to offloaded state
--delete-offloaded-wal
Delete local WAL files after offloading. When disabled, they will be left on disk
--control-file-save-interval <CONTROL_FILE_SAVE_INTERVAL>
Pending updates to control file will be automatically saved after this interval [default: 300s]
```
Manager watches state updates and detects when there are no actvity on
the timeline and actual partial backup upload in remote storage. When
all conditions are met, the state can be switched to offloaded.
In `timeline.rs` there is `StateSK` enum to support switching between
states. When offloaded, code can access only control file structure and
cannot use `SafeKeeper` to accept new WAL.
`FullAccessTimeline` is now renamed to `WalResidentTimeline`. This
struct contains guard to notify manager about active tasks requiring
on-disk WAL access. All guards are issued by the manager, all requests
are sent via channel using `ManagerCtl`. When manager receives request
to issue a guard, it unevicts timeline if it's currently evicted.
Fixed a bug in partial WAL backup, it used `term` instead of
`last_log_term` previously.
After this commit is merged, next step is to roll this change out, as in
issue #6338.
## Problem
We install Postgres 14 in `build-tools` image, but we don't need
it. We use Postgres binaries, which we build ourselves.
## Summary of changes
- Remove Postgresql 14 installation from `build-tools` image
This was a half-finished mechanism to allow a replica to enter hot
standby mode sooner, without waiting for a running-xacts record. It had
issues, and we are working on a better mechanism to replace it.
The control plane might still set the flag in the spec file, but
compute_ctl will simply ignore it.
Adds manual compaction trigger; add gc compaction to test_gc_feedback
Part of https://github.com/neondatabase/neon/issues/8002
```
test_gc_feedback[debug-pg15].logical_size: 50 Mb
test_gc_feedback[debug-pg15].physical_size: 2269 Mb
test_gc_feedback[debug-pg15].physical/logical ratio: 44.5302
test_gc_feedback[debug-pg15].max_total_num_of_deltas: 7
test_gc_feedback[debug-pg15].max_num_of_deltas_above_image: 2
test_gc_feedback[debug-pg15].logical_size_after_bottom_most_compaction: 50 Mb
test_gc_feedback[debug-pg15].physical_size_after_bottom_most_compaction: 287 Mb
test_gc_feedback[debug-pg15].physical/logical ratio after bottom_most_compaction: 5.6312
test_gc_feedback[debug-pg15].max_total_num_of_deltas_after_bottom_most_compaction: 4
test_gc_feedback[debug-pg15].max_num_of_deltas_above_image_after_bottom_most_compaction: 1
```
## Summary of changes
* Add the manual compaction trigger
* Use in test_gc_feedback
* Add a guard to avoid running it with retain_lsns
* Fix: Do `schedule_compaction_update` after compaction
* Fix: Supply deltas in the correct order to reconstruct value
---------
Signed-off-by: Alex Chi Z <chi@neon.tech>
## Problem
These APIs have been deprecated for some time, but were still used from
test code.
Closes: https://github.com/neondatabase/neon/issues/4282
## Summary of changes
- It is still convenient to do a "tenant_attach" from a test without
having to write out a location_conf body, so those test methods have
been retained with implementations that call through to their
location_conf equivalent.
Part of #7497, closes#8120.
## Summary of changes
This PR adds a metric to track the number of valid leases after `GCInfo`
gets refreshed each time.
Besides this metric, we should also track disk space and synthetic size
(after #8071 is closed) to make sure leases are used properly.
Signed-off-by: Yuchen Liang <yuchen@neon.tech>
Part of #7497, closes#8072.
## Problem
Currently the `get_lsn_by_timestamp` and branch creation pageserver APIs do not provide a pleasant client experience where the looked-up LSN might be GC-ed between the two API calls.
This PR attempts to prevent common races between GC and branch creation by making use of LSN leases provided in #8084. A lease can be optionally granted to a looked-up LSN. With the lease, GC will not touch layers needed to reconstruct all pages at this LSN for the duration of the lease.
Signed-off-by: Yuchen Liang <yuchen@neon.tech>
## Problem
For testing, the storage controller has a built-in hack that loads
neon_local endpoint config from disk, and uses it to reconfigure
endpoints when the attached pageserver changes.
Some tests that stop an endpoint while the storage controller is running
could occasionally fail on log errors from the controller trying to use
its special test-mode calls into neon local Endpoint.
Example:
https://neon-github-public-dev.s3.amazonaws.com/reports/pr-8117/9592392425/index.html#/testresult/9d2bb8623d0d53f8
## Summary of changes
- Give NotifyError an explicit NeonLocal variant, to avoid munging these
into generic 500s (I don't want to ignore 500s in general)
- Allow-list errors related to the local notification hook.
The expectation is that tests using endpoints/workloads should be
independently checking that those endpoints work: if neon_local
generates an error inside the storage controller, that's ignorable.
## Problem
There's no way to cancel drain and fill operations.
## Summary of changes
Implement HTTP endpoints to allow cancelling of background operations.
When the operationis cancelled successfully, the node scheduling policy will revert to
`Active`.
In #7957 we enabled deletion without attachment, but retained the
old-style deletion (return 202, delete in background) for attached
tenants. In this PR, we remove the old-style deletion path, such that if
the tenant delete API is invoked while a tenant is detached, it is
simply detached before completing the deletion.
This intentionally doesn't rip out all the old deletion code: in case a
deletion was in progress at time of upgrade, we keep around the code for
finishing it for one release cycle. The rest of the code removal happens
in https://github.com/neondatabase/neon/pull/8091
Now that deletion will always be via the new path, the new path is also
updated to use some retries around remote storage operations, to
tripping up the control plane with 500s if S3 has an intermittent issue.
## Problem
see https://github.com/neondatabase/neon/issues/8070
## Summary of changes
the neon_local subcommands to
- start neon
- start pageserver
- start safekeeper
- start storage controller
get a new option -t=xx or --start-timeout=xx which allows to specify a
longer timeout in seconds we wait for the process start.
This is useful in test cases where the pageserver has to read a lot of
layer data, like in pagebench test cases.
In addition we exploit the new timeout option in the python test
infrastructure (python fixtures) and modify the flaky testcase to
increase the timeout from 10 seconds to 1 minute.
Example from the test execution
```bash
RUST_BACKTRACE=1 NEON_ENV_BUILDER_USE_OVERLAYFS_FOR_SNAPSHOTS=1 DEFAULT_PG_VERSION=15 BUILD_TYPE=release ./scripts/pytest test_runner/performance/pageserver/pagebench/test_pageserver_max_throughput_getpage_at_latest_lsn.py
...
2024-06-19 09:29:34.590 INFO [neon_fixtures.py:1513] Running command "/instance_store/neon/target/release/neon_local storage_controller start --start-timeout=60s"
2024-06-19 09:29:36.365 INFO [broker.py:34] starting storage_broker to listen incoming connections at "127.0.0.1:15001"
2024-06-19 09:29:36.365 INFO [neon_fixtures.py:1513] Running command "/instance_store/neon/target/release/neon_local pageserver start --id=1 --start-timeout=60s"
2024-06-19 09:29:36.366 INFO [neon_fixtures.py:1513] Running command "/instance_store/neon/target/release/neon_local safekeeper start 1 --start-timeout=60s"
```
## Problem
These APIs have be unused for some time. They were superseded by
/location_conf: the equivalent of ignoring a tenant is now to put it in
secondary mode.
## Summary of changes
- Remove APIs
- Remove tests & helpers that used them
- Remove error variants that are no longer needed.
part of Epic https://github.com/neondatabase/neon/issues/7386
# Motivation
The materialized page cache adds complexity to the code base, which
increases the maintenance burden and risk for subtle and hard to
reproduce bugs such as #8050.
Further, the best hit rate that we currently achieve in production is ca
1% of materialized page cache lookups for
`task_kind=PageRequestHandler`. Other task kinds have hit rates <0.2%.
Last, caching page images in Pageserver rewards under-sized caches in
Computes because reading from Pageserver's materialized page cache over
the network is often sufficiently fast (low hundreds of microseconds).
Such Computes should upscale their local caches to fit their working
set, rather than repeatedly requesting the same page from Pageserver.
Some more discussion and context in internal thread
https://neondb.slack.com/archives/C033RQ5SPDH/p1718714037708459
# Changes
This PR removes the materialized page cache code & metrics.
The infrastructure for different key kinds in `PageCache` is left in
place, even though the "Immutable" key kind is the only remaining one.
This can be further simplified in a future commit.
Some tests started failing because their total runtime was dependent on
high materialized page cache hit rates. This test makes them
fixed-runtime or raises pytest timeouts:
* test_local_file_cache_unlink
* test_physical_replication
* test_pg_regress
# Performance
I focussed on ensuring that this PR will not result in a performance
regression in prod.
* **getpage** requests: our production metrics have shown the
materialized page cache to be irrelevant (low hit rate). Also,
Pageserver is the wrong place to cache page images, it should happen in
compute.
* **ingest** (`task_kind=WalReceiverConnectionHandler`): prod metrics
show 0 percent hit rate, so, removing will not be a regression.
* **get_lsn_by_timestamp**: important API for branch creation, used by
control pane. The clog pages that this code uses are not
materialize-page-cached because they're not 8k. No risk of introducing a
regression here.
We will watch the various nightly benchmarks closely for more results
before shipping to prod.
## Problem
Ahem, let's try this again.
https://github.com/neondatabase/neon/pull/8110 had a spooky failure in
test_multi_attach where a call to Endpoint.stop() timed out waiting for
a lock, even though we can see an earlier call completing and releasing
the lock. I suspect something weird is going on with the way pytest runs
tests across processes, or use of asyncio perhaps.
Anyway: the simplest fix is to just use a semaphore instead: if we don't
lock we can't deadlock.
## Summary of changes
- Make Endpoint.running a semaphore, where we add a unit to its counter
when starting the process and atomically decrement it when stopping.
## Problem
Tests using the `Workload` helper would occasionally fail in a strange
way, where the endpoint appears to try and stop twice concurrently, and
the second stop fails because the pidfile is already gone.
`test_multi_attach` suffered from this.
Workload has a `__del__` that stops the endpoint, and python is
destroying this object in a different thread than NeonEnv.stop is
called, resulting in racing stop() calls. Endpoint has a `running`
attribute that avoids calling neon_local's stop twice, but that doesn't
help in the concurrent case.
## Summary of changes
- Make `Endpoint.stop` thread safe with a simple lock held across the
updates to `running` and the actual act of stopping it.
One could also work around this by letting Workload.endpoint outlive the
Workload, or making Workload a context manager, but this change feels
most robust, as it avoids all test code having to know that it must not
try and stop an endpoint from a destructor.
## Problem
We have this set of test utilities which duplicate a tenant by copying
everything that's in remote storage and then attaching a tenant to the
pageserver and storage controller. When the "copied tenants" are created
on the storage controller, they start off from generation number 0. This
means that they can't see anything past that generation.
This issues has existed ever since generation numbers have been
introduced, but we've largely been lucky
for the generation to stay stable during the template tenant creation.
## Summary of Changes
Extend the storage controller debug attach hook to accept a generation
override. Use that in the tenant duplication logic to set the generation
number to something greater than the naturally reached generation. This
allows the tenants to see all layer files.
## Problem
Pageserver restarts cause read availablity downtime for tenants. See
`Motivation` section in the
[RFC](https://github.com/neondatabase/neon/pull/7704).
## Summary of changes
* Introduce a new `NodeSchedulingPolicy`: `PauseForRestart`
* Implement the first take of drain and fill algorithms
* Add a node status endpoint which can be polled to figure out when an
operation is done
The implementation follows the RFC, so it might be useful to peek at it
as you're reviewing.
Since the PR is rather chunky, I've made sure all commits build (with
warnings), so you can
review by commit if you prefer that.
RFC: https://github.com/neondatabase/neon/pull/7704
Related https://github.com/neondatabase/neon/issues/7387
- Make safekeeper read SAFEKEEPER_AUTH_TOKEN env variable with JWT
token to connect to other safekeepers.
- Set it in neon_local when auth is enabled.
- Create simple rust http client supporting it, and use it in pull_timeline
implementation.
- Enable auth in all pull_timeline tests.
- Make sk http_client() by default generate safekeeper wide token, it makes
easier enabling auth in all tests by default.
