This fixes all kinds of problems related to missing params,
like broken timestamps (due to `integer_datetimes`).
This solution is not ideal, but it will help. Meanwhile,
I'm going to dedicate some time to improving connection machinery.
Note that this **does not** fix problems with passing certain parameters
in a reverse direction, i.e. **from client to compute**. This is a
separate matter and will be dealt with in an upcoming PR.
This patch centralize the logic of creating & reading pid files into the
new pid_file module and improves upon / makes explicit a few race conditions
that existed with the previous code.
Starting Processes / Creating Pidfiles
======================================
Before this patch, we had three places that had very similar-looking
match lock_file::create_lock_file { ... }
blocks.
After this change, they can use a straight-forward call provided
by the pid_file:
pid_file::claim_pid_file_for_pid()
Stopping Processes / Reading Pidfiles
=====================================
The new pid_file module provides a function to read a pidfile,
called read_pidfile(), that returns a
pub enum PidFileRead {
NotExist,
NotHeldByAnyProcess(PidFileGuard),
LockedByOtherProcess(Pid),
}
If we get back NotExist, there is nothing to kill.
If we get back NotHeldByAnyProcess, the pid file is stale and we must
ignore its contents.
If it's LockedByOtherProcess, it's either another pidfile reader
or, more likely, the daemon that is still running.
In this case, we can read the pid in the pidfile and kill it.
There's still a small window where this is racy, but it's not a
regression compared to what we have before.
The NotHeldByAnyProcess is an improvement over what we had before
this patch. Before, we would blindly read the pidfile contents
and kill, even if no other process held the flock.
If the pidfile was stale (NotHeldByAnyProcess), then that kill
would either result in ESRCH or hit some other unrelated process
on the system. This patch avoids the latter cacse by grabbing
an exclusive flock before reading the pidfile, and returning the
flock to the caller in the form of a guard object, to avoid
concurrent reads / kills.
It's hopefully irrelevant in practice, but it's a little robustness
that we get for free here.
Maintain flock on Pidfile of ETCD / any InitialPidFile::Create()
================================================================
Pageserver and safekeeper create their pidfiles themselves.
But for etcd, neon_local creates the pidfile (InitialPidFile::Create()).
Before this change, we would unlock the etcd pidfile as soon as
`neon_local start` exits, simply because no-one else kept the FD open.
During `neon_local stop`, that results in a stale pid file,
aka, NotHeldByAnyProcess, and it would henceforth not trust that
the PID stored in the file is still valid.
With this patch, we make the etcd process inherit the pidfile FD,
thereby keeping the flock held until it exits.
Added basic instrumentation to integrate sentry with the proxy, pageserver, and safekeeper processes.
Currently in sentry there are three projects, one for each process. Sentry url is sent to all three processes separately via cli args.
The code in this change was extracted from PR #2595, i.e., Heikki’s draft
PR for on-demand download.
High-Level Changes
- storage_sync module rewrite
- Changes to Tenant Loading
- Changes to Timeline States
- Crash-safe & Resumable Tenant Attach
There are several follow-up work items planned.
Refer to the Epic issue on GitHub:
https://github.com/neondatabase/neon/issues/2029
Metadata:
closes https://github.com/neondatabase/neon/pull/2785
unsquashed history of this patch: archive/pr-2785-storage-sync2/pre-squash
Co-authored-by: Dmitry Rodionov <dmitry@neon.tech>
Co-authored-by: Christian Schwarz <christian@neon.tech>
===============================================================================
storage_sync module rewrite
===========================
The storage_sync code is rewritten. New module name is storage_sync2, mostly to
make a more reasonable git diff.
The updated block comment in storage_sync2.rs describes the changes quite well,
so, we will not reproduce that comment here. TL;DR:
- Global sync queue and RemoteIndex are replaced with per-timeline
`RemoteTimelineClient` structure that contains a queue for UploadOperations
to ensure proper ordering and necessary metadata.
- Before deleting local layer files, wait for ongoing UploadOps to finish
(wait_completion()).
- Download operations are not queued and executed immediately.
Changes to Tenant Loading
=========================
Initial sync part was rewritten as well and represents the other major change
that serves as a foundation for on-demand downloads. Routines for attaching and
loading shifted directly to Tenant struct and now are asynchronous and spawned
into the background.
Since this patch doesn’t introduce on-demand download of layers we fully
synchronize with the remote during pageserver startup. See details in
`Timeline::reconcile_with_remote` and `Timeline::download_missing`.
Changes to Tenant States
========================
The “Active” state has lost its “background_jobs_running: bool” member. That
variable indicated whether the GC & Compaction background loops are spawned or
not. With this patch, they are now always spawned. Unit tests (#[test]) use the
TenantConf::{gc_period,compaction_period} to disable their effect (15db566).
This patch introduces a new tenant state, “Attaching”. A tenant that is being
attached starts in this state and transitions to “Active” once it finishes
download.
The `GET /tenant` endpoints returns `TenantInfo::has_in_progress_downloads`. We
derive the value for that field from the tenant state now, to remain
backwards-compatible with cloud.git. We will remove that field when we switch
to on-demand downloads.
Changes to Timeline States
==========================
The TimelineInfo::awaits_download field is now equivalent to the tenant being
in Attaching state. Previously, download progress was tracked per timeline.
With this change, it’s only tracked per tenant. When on-demand downloads
arrive, the field will be completely obsolete. Deprecation is tracked in
isuse #2930.
Crash-safe & Resumable Tenant Attach
====================================
Previously, the attach operation was not persistent. I.e., when tenant attach
was interrupted by a crash, the pageserver would not continue attaching after
pageserver restart. In fact, the half-finished tenant directory on disk would
simply be skipped by tenant_mgr because it lacked the metadata file (it’s
written last). This patch introduces an “attaching” marker file inside that is
present inside the tenant directory while the tenant is attaching. During
pageserver startup, tenant_mgr will resume attach if that file is present. If
not, it assumes that the local tenant state is consistent and tries to load the
tenant. If that fails, the tenant transitions into Broken state.
* Fix https://github.com/neondatabase/neon/issues/1854
* Never log Safekeeper::conninfo in walproposer as it now contains a secret token
* control_panel, test_runner: generate and pass JWT tokens for Safekeeper to compute and pageserver
* Compute: load JWT token for Safekepeer from the environment variable. Do not reuse the token from
pageserver_connstring because it's embedded in there weirdly.
* Pageserver: load JWT token for Safekeeper from the environment variable.
* Rewrite docs/authentication.md
There will be different scopes for those two, so authorization code should be different.
The `check_permission` function is now not in the shared library. Its implementation
is very similar to the one which will be added for Safekeeper. In fact, we may reuse
the same existing root-like 'PageServerApi' scope, but I would prefer to have separate
root-like scopes for services.
Also, generate_management_token in tests is generate_pageserver_token now.
Which ought to replace etcd. This patch only adds the binary and adjusts
Dockerfile to include it; subsequent ones will add deploy of helm chart and the
actual replacement.
It is a simple and fast pub-sub message bus. In this patch only safekeeper
message is supported, but others can be easily added.
Compilation now requires protoc to be installed. Installing protobuf-compiler
package is fine for Debian/Ubuntu.
ref
https://github.com/neondatabase/neon/pull/2733https://github.com/neondatabase/neon/issues/2394
Tenant size information is gathered by using existing parts of
`Tenant::gc_iteration` which are now separated as
`Tenant::refresh_gc_info`. `Tenant::refresh_gc_info` collects branch
points, and invokes `Timeline::update_gc_info`; nothing was supposed to
be changed there. The gathered branch points (through Timeline's
`GcInfo::retain_lsns`), `GcInfo::horizon_cutoff`, and
`GcInfo::pitr_cutoff` are used to build up a Vec of updates fed into the
`libs/tenant_size_model` to calculate the history size.
The gathered information is now exposed using `GET
/v1/tenant/{tenant_id}/size`, which which will respond with the actual
calculated size. Initially the idea was to have this delivered as tenant
background task and exported via metric, but it might be too
computationally expensive to run it periodically as we don't yet know if
the returned values are any good.
Adds one new metric:
- pageserver_storage_operations_seconds with label `logical_size`
- separating from original `init_logical_size`
Adds a pageserver wide configuration variable:
- `concurrent_tenant_size_logical_size_queries` with default 1
This leaves a lot of TODO's, tracked on issue #2748.
* Support configuring the log format as json or plain.
Separately test json and plain logger. They would be competing on the
same global subscriber otherwise.
* Implement log_format for pageserver config
* Implement configurable log format for safekeeper.
This API is rather pointless, as sane choice anyway requires knowledge of peers
status and leaders lifetime in any case can intersect, which is fine for us --
so manual elections are straightforward. Here, we deterministically choose among
the reasonably caught up safekeepers, shifting by timeline id to spread the
load.
A step towards custom broker https://github.com/neondatabase/neon/issues/2394
Part of https://github.com/neondatabase/neon/pull/2239
Regular, from scratch, timeline creation involves initdb to be run in a separate directory, data from this directory to be imported into pageserver and, finally, timeline-related background tasks to start.
This PR ensures we don't leave behind any directories that are not marked as temporary and that pageserver removes such directories on restart, allowing timeline creation to be retried with the same IDs, if needed.
It would be good to later rewrite the logic to use a temporary directory, similar what tenant creation does.
Yet currently it's harder than this change, so not done.
* etcd-client is not updated, since we plan to replace it with another client and the new version errors with some missing prost library error
* clap had released another major update that requires changing every CLI declaration again, deserves a separate PR
With the ability to pass commit_lsn. This allows to perform project WAL recovery
through different (from the original) set of safekeepers (or under different
ttid) by
1) moving WAL files to s3 under proper ttid;
2) explicitly creating timeline on safekeepers, setting commit_lsn to the
latest point;
3) putting the lastest .parital file to the timeline directory on safekeepers, if
desired.
Extend test_s3_wal_replay to exersise this behaviour.
Also extends timeline_status endpoint to return postgres information.
We had a problem where almost all of the threads were waiting on a futex syscall. More specifically:
- `/metrics` handler was inside `TimelineCollector::collect()`, waiting on a mutex for a single Timeline
- This exact timeline was inside `control_file::FileStorage::persist()`, waiting on a mutex for Lazy initialization of `PERSIST_CONTROL_FILE_SECONDS`
- `PERSIST_CONTROL_FILE_SECONDS: Lazy<Histogram>` was blocked on `prometheus::register`
- `prometheus::register` calls `DEFAULT_REGISTRY.write().register()` to take a write lock on Registry and add a new metric
- `DEFAULT_REGISTRY` lock was already taken inside `DEFAULT_REGISTRY.gather()`, which was called by `/metrics` handler to collect all metrics
This commit creates another Registry with a separate lock, to avoid deadlock in a case where `TimelineCollector` triggers registration of new metrics inside default registry.
Part of the general work on improving pageserver logs.
Brief summary of changes:
* Remove `ApiError::from_err`
* Remove `impl From<anyhow::Error> for ApiError`
* Convert `ApiError::{BadRequest, NotFound}` to use `anyhow::Error`
* Note: `NotFound` has more verbose formatting because it's more
likely to have useful information for the receiving "user"
* Explicitly convert from `tokio::task::JoinError`s into
`InternalServerError`s where appropriate
Also note: many of the places where errors were implicitly converted to
500s have now been updated to return a more appropriate error. Some
places where it's not yet possible to distinguish the error types have
been left as 500s.
Follow-up to PR #2433 (b8eb908a). There's still a few more unresolved
locations that have been left as-is for the same compatibility reasons
in the original PR.
Instead of spawning helper threads, we now use Tokio tasks. There
are multiple Tokio runtimes, for different kinds of tasks. One for
serving libpq client connections, another for background operations
like GC and compaction, and so on. That's not strictly required, we
could use just one runtime, but with this you can still get an
overview of what's happening with "top -H".
There's one subtle behavior in how TenantState is updated. Before this
patch, if you deleted all timelines from a tenant, its GC and
compaction loops were stopped, and the tenant went back to Idle
state. We no longer do that. The empty tenant stays Active. The
changes to test_tenant_tasks.py are related to that.
There's still plenty of synchronous code and blocking. For example, we
still use blocking std::io functions for all file I/O, and the
communication with WAL redo processes is still uses low-level unix
poll(). We might want to rewrite those later, but this will do for
now. The model is that local file I/O is considered to be fast enough
that blocking - and preventing other tasks running in the same thread -
is acceptable.
Previously, proxy didn't forward auxiliary `options` parameter
and other ones to the client's compute node, e.g.
```
$ psql "user=john host=localhost dbname=postgres options='-cgeqo=off'"
postgres=# show geqo;
┌──────┐
│ geqo │
├──────┤
│ on │
└──────┘
(1 row)
```
With this patch we now forward `options`, `application_name` and `replication`.
Further reading: https://www.postgresql.org/docs/current/libpq-connect.htmlFixes#1287.
`latest_gc_cutoff_lsn` tracks the cutoff point where GC has been
performed. Anything older than the cutoff might already have been GC'd
away, and cannot be queried by get_page_at_lsn requests. It's
protected by an RWLock. Whenever a get_page_at_lsn requests comes in,
it first grabs the lock and reads the current `latest_gc_cutoff`, and
holds the lock it until the request has been served. The lock ensures
that GC doesn't start concurrently and remove page versions that we
still need to satisfy the request.
With the lock, get_page_at_lsn request could potentially be blocked
for a long time. GC only holds the lock in exclusive mode for a short
duration, but depending on how whether the RWLock is "fair", a read
request might be queued behind the GC's exclusive request, which in
turn might be queued behind a long-running read operation, like a
basebackup. If the lock implementation is not fair, i.e. if a reader
can always jump the queue if the lock is already held in read mode,
then another problem arises: GC might be starved if a constant stream
of GetPage requests comes in.
To avoid the long wait or starvation, introduce a Read-Copy-Update
mechanism to replace the lock on `latest_gc_cutoff_lsn`. With the RCU,
reader can always read the latest value without blocking (except for a
very short duration if the lock protecting the RCU is contended;
that's comparable to a spinlock). And a writer can always write a new
value without waiting for readers to finish using the old value. The
old readers will continue to see the old value through their guard
object, while new readers will see the new value.
This is purely theoretical ATM, we don't have any reports of either
starvation or blocking behind GC happening in practice. But it's
simple to fix, so let's nip that problem in the bud.
`///` is used for comments on the *next* code that follows, so the comment
actually applied to the `use std::collections::BTreeMap;` line that follows.
rustfmt complained about that:
error: an inner attribute is not permitted following an outer doc comment
--> /home/heikki/git-sandbox/neon/libs/utils/src/seqwait_async.rs:7:1
|
5 | ///
| --- previous doc comment
6 |
7 | #![warn(missing_docs)]
| ^^^^^^^^^^^^^^^^^^^^^^ not permitted following an outer attribute
8 |
9 | use std::collections::BTreeMap;
| ------------------------------- the inner attribute doesn't annotate this `use` import
|
= note: inner attributes, like `#![no_std]`, annotate the item enclosing them, and are usually found at the beginning of source files
help: to annotate the `use` import, change the attribute from inner to outer style
|
7 - #![warn(missing_docs)]
7 + #[warn(missing_docs)]
|
`//!` is the correct syntax for comments that apply to the whole file.
[proxy] Add the `password hack` authentication flow
This lets us authenticate users which can use neither
SNI (due to old libpq) nor connection string `options`
(due to restrictions in other client libraries).
Note: `PasswordHack` will accept passwords which are not
encoded in base64 via the "password" field. The assumption
is that most user passwords will be valid utf-8 strings,
and the rest may still be passed via "password_".
* Added project option in case SNI data is missing. Resolving issue #1745.
* Added invariant checking for project name: if both sni_data and project_name are available then they should match.
- Uncomment accidently `self.keep_alive.abort()` commented line, due to this
task never finished, which blocked launcher.
- Mess up with initialization one more time, to fix offloader trying to back up
segment 0. Now we initialize all required LSNs in handle_elected,
where we learn start LSN for the first time.
- Fix blind attempt to provide safekeeper service file with remote storage
params.
Separate task is launched for each timeline and stopped when timeline doesn't
need offloading. Decision who offloads is done through etcd leader election;
currently there is no pre condition for participating, that's a TODO.
neon_local and tests infrastructure for remote storage in safekeepers added,
along with the test itself.
ref #1009
Co-authored-by: Anton Shyrabokau <ahtoxa@Antons-MacBook-Pro.local>
