33682fd14e
Previously, config_updater used a serialized_action to trigger update_config() when object_storage_endpoints changed. Because serialized_action::trigger() always schedules the action as a new reactor task (via semaphore::wait().then()), there was a window between the config value becoming visible to the REST API and update_config() actually running. This allowed a concurrent CREATE KEYSPACE to see the new endpoint via is_known_endpoint() before storage_manager had registered it in _object_storage_endpoints. Now config observers run synchronously in a reactor turn and must not suspend. Split the previous monolithic async update_config() coroutine into two phases: - Sync (in the observer, never suspends): storage_manager::_object_storage_endpoints is updated in place; for already-instantiated clients, update_config_sync swaps the new config atomically - Async (per-client gate): background fibers finish the work that can't run in the observer — S3 refreshes credentials under _creds_sem; GCS drains and closes the replaced client. Config reloads triggered by SIGHUP are applied on shard 0 and then broadcast to all other shards. An rwlock has been also introduced to make sure that the configuration has been propagated to all cores. This guarantees that a client requesting a config via the REST API will see a consistent snapshot Fixes: https://scylladb.atlassian.net/browse/SCYLLADB-757 Fixes: [28141](https://github.com/scylladb/scylladb/issues/28141) Closes scylladb/scylladb#28950 * github.com:scylladb/scylladb: test/object_store: verify object storage client creation and live reconfiguration sstables/utils/s3: split config update into sync and async parts test_config: improve logging for wait_for_config API db: introduce read-write lock to synchronize config updates with REST API
Scylla
What is Scylla?
Scylla is the real-time big data database that is API-compatible with Apache Cassandra and Amazon DynamoDB. Scylla embraces a shared-nothing approach that increases throughput and storage capacity to realize order-of-magnitude performance improvements and reduce hardware costs.
For more information, please see the ScyllaDB web site.
Build Prerequisites
Scylla is fairly fussy about its build environment, requiring very recent versions of the C++23 compiler and of many libraries to build. The document HACKING.md includes detailed information on building and developing Scylla, but to get Scylla building quickly on (almost) any build machine, Scylla offers a frozen toolchain. This is a pre-configured Docker image which includes recent versions of all the required compilers, libraries and build tools. Using the frozen toolchain allows you to avoid changing anything in your build machine to meet Scylla's requirements - you just need to meet the frozen toolchain's prerequisites (mostly, Docker or Podman being available).
Building Scylla
Building Scylla with the frozen toolchain dbuild is as easy as:
$ git submodule update --init --force --recursive
$ ./tools/toolchain/dbuild ./configure.py
$ ./tools/toolchain/dbuild ninja build/release/scylla
For further information, please see:
- Developer documentation for more information on building Scylla.
- Build documentation on how to build Scylla binaries, tests, and packages.
- Docker image build documentation for information on how to build Docker images.
Running Scylla
To start Scylla server, run:
$ ./tools/toolchain/dbuild ./build/release/scylla --workdir tmp --smp 1 --developer-mode 1
This will start a Scylla node with one CPU core allocated to it and data files stored in the tmp directory.
The --developer-mode is needed to disable the various checks Scylla performs at startup to ensure the machine is configured for maximum performance (not relevant on development workstations).
Please note that you need to run Scylla with dbuild if you built it with the frozen toolchain.
For more run options, run:
$ ./tools/toolchain/dbuild ./build/release/scylla --help
Testing
See test.py manual.
Scylla APIs and compatibility
By default, Scylla is compatible with Apache Cassandra and its API - CQL. There is also support for the API of Amazon DynamoDB™, which needs to be enabled and configured in order to be used. For more information on how to enable the DynamoDB™ API in Scylla, and the current compatibility of this feature as well as Scylla-specific extensions, see Alternator and Getting started with Alternator.
Documentation
Documentation can be found here. Seastar documentation can be found here. User documentation can be found here.
Training
Training material and online courses can be found at Scylla University. The courses are free, self-paced and include hands-on examples. They cover a variety of topics including Scylla data modeling, administration, architecture, basic NoSQL concepts, using drivers for application development, Scylla setup, failover, compactions, multi-datacenters and how Scylla integrates with third-party applications.
Contributing to Scylla
If you want to report a bug or submit a pull request or a patch, please read the contribution guidelines.
If you are a developer working on Scylla, please read the developer guidelines.
Contact
- The community forum and Slack channel are for users to discuss configuration, management, and operations of ScyllaDB.
- The developers mailing list is for developers and people interested in following the development of ScyllaDB to discuss technical topics.