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bc1985b8ce
Freezing large mutations synchronously may cause
reactor stalls, as seen in the test_add_many_nodes_under_load
dtest:
```
++[1#1/37 5%] addr=0x15b0bf total=99 count=2 avg=50: ?? ??:0
| ++[2#1/2 67%] addr=0x15a331f total=66 count=1 avg=66:
| | bytes_ostream::write at ././bytes_ostream.hh:248
| | (inlined by) bytes_ostream::write at ././bytes_ostream.hh:263
| | (inlined by) ser::serialize_integral<unsigned int, bytes_ostream> at ././serializer.hh:203
| | (inlined by) ser::integral_serializer<unsigned int>::write<bytes_ostream> at ././serializer.hh:217
| | (inlined by) ser::serialize<unsigned int, bytes_ostream> at ././serializer.hh:254
| | (inlined by) ser::writer_of_column<bytes_ostream>::write_id at ./build/dev/gen/idl/mutation.dist.impl.hh:4680
| | ++[3#1/1 100%] addr=0x159df71 total=132 count=2 avg=66:
| | | (anonymous namespace)::write_row_cells<ser::deletable_row__cells<bytes_ostream> >(ser::deletable_row__cells<bytes_ostream>&&, row const&, schema const&, column_kind)::{lambda(unsigned int, atomic_cell_or_collection const&)#1}::operator() at ./mutation/mutation_partition_serializer.cc:99
| | | (inlined by) row::maybe_invoke_with_hash<(anonymous namespace)::write_row_cells<ser::deletable_row__cells<bytes_ostream> >(ser::deletable_row__cells<bytes_ostream>&&, row const&, schema const&, column_kind)::{lambda(unsigned int, atomic_cell_or_collection const&)#1} const, cell_and_hash const> at ./mutation/mutation_partition.hh:133
| | | (inlined by) row::for_each_cell<(anonymous namespace)::write_row_cells<ser::deletable_row__cells<bytes_ostream> >(ser::deletable_row__cells<bytes_ostream>&&, row const&, schema const&, column_kind)::{lambda(unsigned int, atomic_cell_or_collection const&)#1}>(ser::deletable_row__cells<bytes_ostream>&&) const::{lambda(unsigned int, cell_and_hash const&)#1}::operator() at ./mutation/mutation_partition.hh:152
| | | (inlined by) compact_radix_tree::tree<cell_and_hash, unsigned int>::walking_visitor<row::for_each_cell<(anonymous namespace)::write_row_cells<ser::deletable_row__cells<bytes_ostream> >(ser::deletable_row__cells<bytes_ostream>&&, row const&, schema const&, column_kind)::{lambda(unsigned int, atomic_cell_or_collection const&)#1}>(ser::deletable_row__cells<bytes_ostream>&&) const::{lambda(unsigned int, cell_and_hash const&)#1}, true>::operator() at ././utils/compact-radix-tree.hh:1888
| | | (inlined by) compact_radix_tree::tree<cell_and_hash, unsigned int>::visit_slot<compact_radix_tree::tree<cell_and_hash, unsigned int>::walking_visitor<row::for_each_cell<(anonymous namespace)::write_row_cells<ser::deletable_row__cells<bytes_ostream> >(ser::deletable_row__cells<bytes_ostream>&&, row const&, schema const&, column_kind)::{lambda(unsigned int, atomic_cell_or_collection const&)#1}>(ser::deletable_row__cells<bytes_ostream>&&) const::{lambda(unsigned int, cell_and_hash const&)#1}, true>&> at ././utils/compact-radix-tree.hh:1560
| | ++ - addr=0x159d84d:
| | | compact_radix_tree::tree<cell_and_hash, unsigned int>::indirect_layout<cell_and_hash, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)1, 4u, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)2, 0u, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)0, 0u>::visit<compact_radix_tree::tree<cell_and_hash, unsigned int>::walking_visitor<row::for_each_cell<(anonymous namespace)::write_row_cells<ser::deletable_row__cells<bytes_ostream> >(ser::deletable_row__cells<bytes_ostream>&&, row const&, schema const&, column_kind)::{lambda(unsigned int, atomic_cell_or_collection const&)#1}>(ser::deletable_row__cells<bytes_ostream>&&) const::{lambda(unsigned int, cell_and_hash const&)#1}, true>&> at ././utils/compact-radix-tree.hh:1364
| | | (inlined by) compact_radix_tree::tree<cell_and_hash, unsigned int>::node_base<cell_and_hash, compact_radix_tree::tree<cell_and_hash, unsigned int>::indirect_layout<cell_and_hash, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)1, 4u, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)2, 0u, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)0, 0u>, compact_radix_tree::tree<cell_and_hash, unsigned int>::indirect_layout<cell_and_hash, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)2, 8u, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)3, 0u, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)1, 4u>, compact_radix_tree::tree<cell_and_hash, unsigned int>::indirect_layout<cell_and_hash, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)3, 16u, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)4, 0u, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)2, 8u>, compact_radix_tree::tree<cell_and_hash, unsigned int>::indirect_layout<cell_and_hash, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)4, 32u, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)6, 0u, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)3, 16u>, compact_radix_tree::tree<cell_and_hash, unsigned int>::direct_layout<cell_and_hash, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)6, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)0, 0u, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)4, 32u> >::visit<compact_radix_tree::tree<cell_and_hash, unsigned int>::walking_visitor<row::for_each_cell<(anonymous namespace)::write_row_cells<ser::deletable_row__cells<bytes_ostream> >(ser::deletable_row__cells<bytes_ostream>&&, row const&, schema const&, column_kind)::{lambda(unsigned int, atomic_cell_or_collection const&)#1}>(ser::deletable_row__cells<bytes_ostream>&&) const::{lambda(unsigned int, cell_and_hash const&)#1}, true>&, compact_radix_tree::tree<cell_and_hash, unsigned int>::indirect_layout<cell_and_hash, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)1, 4u, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)2, 0u, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)0, 0u>, compact_radix_tree::tree<cell_and_hash, unsigned int>::indirect_layout<cell_and_hash, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)2, 8u, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)3, 0u, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)1, 4u>, compact_radix_tree::tree<cell_and_hash, unsigned int>::indirect_layout<cell_and_hash, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)3, 16u, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)4, 0u, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)2, 8u>, compact_radix_tree::tree<cell_and_hash, unsigned int>::indirect_layout<cell_and_hash, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)4, 32u, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)6, 0u, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)3, 16u>, compact_radix_tree::tree<cell_and_hash, unsigned int>::direct_layout<cell_and_hash, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)6, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)0, 0u, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)4, 32u> > at ././utils/compact-radix-tree.hh:799
| | | (inlined by) compact_radix_tree::tree<cell_and_hash, unsigned int>::node_base<cell_and_hash, compact_radix_tree::tree<cell_and_hash, unsigned int>::indirect_layout<cell_and_hash, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)1, 4u, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)2, 0u, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)0, 0u>, compact_radix_tree::tree<cell_and_hash, unsigned int>::indirect_layout<cell_and_hash, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)2, 8u, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)3, 0u, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)1, 4u>, compact_radix_tree::tree<cell_and_hash, unsigned int>::indirect_layout<cell_and_hash, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)3, 16u, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)4, 0u, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)2, 8u>, compact_radix_tree::tree<cell_and_hash, unsigned int>::indirect_layout<cell_and_hash, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)4, 32u, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)6, 0u, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)3, 16u>, compact_radix_tree::tree<cell_and_hash, unsigned int>::direct_layout<cell_and_hash, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)6, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)0, 0u, (compact_radix_tree::tree<cell_and_hash, unsigned int>::layout)4, 32u> >::visit<compact_radix_tree::tree<cell_and_hash, unsigned int>::walking_visitor<row::for_each_cell<(anonymous namespace)::write_row_cells<ser::deletable_row__cells<bytes_ostream> >(ser::deletable_row__cells<bytes_ostream>&&, row const&, schema const&, column_kind)::{lambda(unsigned int, atomic_cell_or_collection const&)#1}>(ser::deletable_row__cells<bytes_ostream>&&) const::{lambda(unsigned int, cell_and_hash const&)#1}, true>&> at ././utils/compact-radix-tree.hh:807
| | ++[4#1/1 100%] addr=0x1596f4a total=329 count=5 avg=66:
| | | compact_radix_tree::tree<cell_and_hash, unsigned int>::node_head::visit<compact_radix_tree::tree<cell_and_hash, unsigned int>::walking_visitor<row::for_each_cell<(anonymous namespace)::write_row_cells<ser::deletable_row__cells<bytes_ostream> >(ser::deletable_row__cells<bytes_ostream>&&, row const&, schema const&, column_kind)::{lambda(unsigned int, atomic_cell_or_collection const&)#1}>(ser::deletable_row__cells<bytes_ostream>&&) const::{lambda(unsigned int, cell_and_hash const&)#1}, true> > at ././utils/compact-radix-tree.hh:473
| | | (inlined by) compact_radix_tree::tree<cell_and_hash, unsigned int>::visit<compact_radix_tree::tree<cell_and_hash, unsigned int>::walking_visitor<row::for_each_cell<(anonymous namespace)::write_row_cells<ser::deletable_row__cells<bytes_ostream> >(ser::deletable_row__cells<bytes_ostream>&&, row const&, schema const&, column_kind)::{lambda(unsigned int, atomic_cell_or_collection const&)#1}>(ser::deletable_row__cells<bytes_ostream>&&) const::{lambda(unsigned int, cell_and_hash const&)#1}, true> > at ././utils/compact-radix-tree.hh:1626
| | | (inlined by) compact_radix_tree::tree<cell_and_hash, unsigned int>::walk<row::for_each_cell<(anonymous namespace)::write_row_cells<ser::deletable_row__cells<bytes_ostream> >(ser::deletable_row__cells<bytes_ostream>&&, row const&, schema const&, column_kind)::{lambda(unsigned int, atomic_cell_or_collection const&)#1}>(ser::deletable_row__cells<bytes_ostream>&&) const::{lambda(unsigned int, cell_and_hash const&)#1}> at ././utils/compact-radix-tree.hh:1909
| | | (inlined by) row::for_each_cell<(anonymous namespace)::write_row_cells<ser::deletable_row__cells<bytes_ostream> >(ser::deletable_row__cells<bytes_ostream>&&, row const&, schema const&, column_kind)::{lambda(unsigned int, atomic_cell_or_collection const&)#1}> at ./mutation/mutation_partition.hh:151
| | | (inlined by) (anonymous namespace)::write_row_cells<ser::deletable_row__cells<bytes_ostream> > at ./mutation/mutation_partition_serializer.cc:97
| | | (inlined by) write_row<ser::writer_of_deletable_row<bytes_ostream> > at ./mutation/mutation_partition_serializer.cc:168
| | ++[5#1/2 80%] addr=0x15a310c total=263 count=4 avg=66:
| | | mutation_partition_serializer::write_serialized<ser::writer_of_mutation_partition<bytes_ostream> > at ./mutation/mutation_partition_serializer.cc:180
| | | ++[6#1/2 62%] addr=0x14eb60a total=428 count=7 avg=61:
| | | | frozen_mutation::frozen_mutation(mutation const&)::$_0::operator()<ser::writer_of_mutation_partition<bytes_ostream> > at ./mutation/frozen_mutation.cc:85
| | | | (inlined by) ser::after_mutation__key<bytes_ostream>::partition<frozen_mutation::frozen_mutation(mutation const&)::$_0> at ./build/dev/gen/idl/mutation.dist.impl.hh:7058
| | | | (inlined by) frozen_mutation::frozen_mutation at ./mutation/frozen_mutation.cc:84
| | | | ++[7#1/1 100%] addr=0x14ed388 total=532 count=9 avg=59:
| | | | | freeze at ./mutation/frozen_mutation.cc:143
| | | | ++[8#1/2 74%] addr=0x252cf55 total=394 count=6 avg=66:
| | | | | service::storage_service::merge_topology_snapshot at ./service/storage_service.cc:763
```
This change uses freeze_gently to freeze
the cdc_generations_v2 mutations one at a time
to prevent the stalls reported above.
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
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++20 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 APIs - CQL and Thrift. 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 the ScyllaDB open source.
- The developers mailing list is for developers and people interested in following the development of ScyllaDB to discuss technical topics.