e1845ef5f8
Populate the local state during gossiper initialization in start_gossiping, preventing an empty state from being added to _endpoint_state_map and returned in get_endpoint_states responses, that was causing an 'empty host id issue' on the other nodes during nodes restart. Check for a race condition in do_apply_state_locally In do_apply_state_locally, a race condition can occur if a task is suspended at a preemption point while the node entry is not locked. During this time, the host may be removed from _endpoint_state_map. When the task resumes, this can lead to inserting an entry with an empty host ID into the map, causing various errors, including a node crash. This change adds a check after locking the map entry: if a gossip ACK update does not contain a host ID, we verify that an entry with that host ID still exists in the gossiper’s _endpoint_state_map. Fixes https://github.com/scylladb/scylladb/issues/25831 Fixes https://github.com/scylladb/scylladb/issues/25803 Fixes https://github.com/scylladb/scylladb/issues/25702 Fixes https://github.com/scylladb/scylladb/issues/25621 Ref https://github.com/scylladb/scylla-enterprise/issues/5613 Backport: The issue affects all current releases(2025.x), therefore this PR needs to be backported to all 2025.1-2025.3. - (cherry picked from commit28e0f42a83) - (cherry picked from commitf08df7c9d7) - (cherry picked from commit775642ea23) - (cherry picked from commitb34d543f30) Parent PR: #25849 Closes scylladb/scylladb#25897 * https://github.com/scylladb/scylladb: gossiper: fix empty initial local node state gossiper: add test for a race condition in start_gossiping gossiper: check for a race condition in `do_apply_state_locally` test/gossiper: add reproducible test for race condition during node decommission
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.