54bddeb3b5
With the goal of avoiding stalls on writing large collections, like
below:
++[0#1/1 100%] addr=0x5422d1e total=32 count=1 avg=32:
| seastar::backtrace<seastar::backtrace_buffer::append_backtrace_oneline()::{lambda(seastar::frame)#1}> at ./build/release/seastar/./seastar/include/seastar/util/backtrace.hh:85
++ - addr=0x541b6d4:
| seastar::backtrace_buffer::append_backtrace_oneline at ./build/release/seastar/./seastar/src/core/reactor.cc:811
| (inlined by) seastar::print_with_backtrace at ./build/release/seastar/./seastar/src/core/reactor.cc:838
++ - addr=0x541afb7:
| seastar::internal::cpu_stall_detector::generate_trace at ./build/release/seastar/./seastar/src/core/reactor.cc:1479
++ - addr=0x541b86c:
| seastar::internal::cpu_stall_detector::maybe_report at ./build/release/seastar/./seastar/src/core/reactor.cc:1214
| (inlined by) seastar::internal::cpu_stall_detector::on_signal at ./build/release/seastar/./seastar/src/core/reactor.cc:1234
| (inlined by) seastar::reactor::block_notifier at ./build/release/seastar/./seastar/src/core/reactor.cc:1548
/opt/scylladb/libreloc/libc.so.6: ELF 64-bit LSB shared object, x86-64, version 1 (GNU/Linux), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, BuildID[sha1]=f83d43b9b4b0ed5c2bd0a1613bf33e08ee054c93, for GNU/Linux 3.2.0, not stripped
++ - addr=/opt/scylladb/libreloc/libc.so.6+0x1a28f:
| sigpending at ??:0
++ - addr=0x1760bf6:
| std::basic_string_view<signed char, std::char_traits<signed char> >::remove_prefix at /usr/lib/gcc/x86_64-redhat-linux/15/../../../../include/c++/15/string_view:302
| (inlined by) managed_bytes_basic_view<(mutable_view)0>::remove_prefix at ././utils/managed_bytes.hh:421
| (inlined by) _Z11read_simpleIlTk14FragmentedView24managed_bytes_basic_viewIL12mutable_view0EEET_RT0_ at ././utils/fragment_range.hh:365
| (inlined by) _ZL9get_fieldIlTk14FragmentedView24managed_bytes_basic_viewIL12mutable_view0EEQsr3stdE12is_trivial_vIT_EES3_T0_j at ././mutation/atomic_cell.hh:62
| (inlined by) atomic_cell_type::timestamp at ././mutation/atomic_cell.hh:103
| (inlined by) basic_atomic_cell_view<(mutable_view)0>::timestamp at ././mutation/atomic_cell.hh:232
| (inlined by) sstables::mc::writer::write_cell at ./sstables/mx/writer.cc:1101
| (inlined by) sstables::mc::writer::write_collection(bytes_ostream&, clustering_key_prefix const*, column_definition const&, collection_mutation_view, sstables::mc::writer::row_time_properties const&, bool)::$_0::operator() at ./sstables/mx/writer.cc:1233
| (inlined by) collection_mutation_view::with_deserialized<sstables::mc::writer::write_collection(bytes_ostream&, clustering_key_prefix const*, column_definition const&, collection_mutation_view, sstables::mc::writer::row_time_properties const&, bool)::$_0> at ././mutation/collection_mutation.hh:97
| (inlined by) sstables::mc::writer::write_collection at ./sstables/mx/writer.cc:1221
++ - addr=0x1677af3:
| sstables::mc::writer::write_cells at ./sstables/mx/writer.cc:1261
| (inlined by) sstables::mc::writer::write_row_body at ./sstables/mx/writer.cc:1287
| (inlined by) sstables::mc::writer::write_clustered at ./sstables/mx/writer.cc:1377
| (inlined by) _ZN8sstables2mc6writer15write_clusteredI14clustering_rowQ9ClusteredIT_EEEvRKS4_9tombstone at ./sstables/mx/writer.cc:766
| (inlined by) sstables::mc::writer::consume at ./sstables/mx/writer.cc:1425
Putting the yield in write_cell() instead of in write_collection() means
that writing any row benefits from the added yield point in the middle.
Refs: SCYLLADB-964
Closes scylladb/scylladb#28948
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.