4018dc7f0d
File based stream is a new feature that optimizes tablet movement
significantly. It streams the entire SSTable files without deserializing
SSTable files into mutation fragments and re-serializing them back into
SSTables on receiving nodes. As a result, less data is streamed over the
network, and less CPU is consumed, especially for data models that
contain small cells.
The following patches are imported from the scylla enterprise:
*) Merge 'Introduce file stream for tablet' from Asias He
This patch uses Seastar RPC stream interface to stream sstable files on
network for tablet migration.
It streams sstables instead of mutation fragments. The file based
stream has multiple advantages over the mutation streaming.
- No serialization or deserialization for mutation fragments
- No need to read and process each mutation fragments
- On wire data is more compact and smaller
In the test below, a significant speed up is observed.
Two nodes, 1 shard per node, 1 initial_tablets:
- Start node 1
- Insert 10M rows of data with c-s
- Bootstrap node 2
Node 1 will migration data to node2 with the file stream.
Test results:
1) File stream: bytes on wire = 1132006250 bytes, bw = 836MB/s
[shard 0:stre] stream_blob - stream_sstables[eadaa8e0-a4f2-4cc6-bf10-39ad1ce106b0]
Finished sending sstable_nr=2 files_nr=18 files={} range=(-1,9223372036854775807] bytes_sent=1132006250 stream_bw=836MB/s
[shard 0:stre] storage_service - Streaming for tablet migration of a4f68900-568a-11ee-b7b9-c2b13945eed2:1 took 1.08004s seconds
2) Mutation stream: bytes on wire = 3030004736 bytes, bw = 125410.87 KiB/s = 128MB/s
[shard 0:stre] stream_session - [Stream #406dc8b0-56b5-11ee-bc2d-000bf4871058]
Streaming plan for Tablet migration-ks1-index-0 succeeded, peers={127.0.0.1}, tx=0 KiB, 0.00 KiB/s, rx=2958989 KiB, 125410.87 KiB/s
[shard 0:stre] storage_service - Streaming for tablet migration of a4f68900-568a-11ee-b7b9-c2b13945eed2:1 took 23.5992s seconds
Test Summary:
File stream v.s. Mutation stream improvements
- Stream bandwidth = 836 / 128 (MB/s) = 6.53X
- Stream time = 23.60 / 1.08 (Seconds) = 21.85X
- Stream bytes on wire = 3030004736 / 1132006250 (Bytes)= 2.67X
Closes scylladb/scylla-enterprise#3438
* github.com:scylladb/scylla-enterprise:
tests: Add file_stream_test
streaming: Implement file stream for tablet
*) streaming: Use new take_storage_snapshot interface
The new take_storage_snapshot returns a file object instead of a file
name. This allows the file stream sender to read from the file even if
the file is deleted by compaction.
Closes scylladb/scylla-enterprise#3728
*) streaming: Protect unsupported file types for file stream
Currently, we assume the file streamed over the stream_blob rpc verb is
a sstable file. This patch rejects the unsupported file types on the
receiver side. This allows us to stream more file types later using the
current file stream infrastructure without worrying about old nodes
processing the new file types in the wrong way.
- The file_ops::noop is renamed to file_ops::stream_sstables to be
explicit about the file types
- A missing test_file_stream_error_injection is added to the idl
Fixes: #3846
Tests: test_unsupported_file_ops
Closes scylladb/scylla-enterprise#3847
*) idl: Add service::session_id id to idl
It will be used in the next patch.
Refs #3907
*) streaming: Protect file stream with topology_guard
Similar to "storage_service, tablets: Use session to guard tablet
streaming", this patch protects file stream with topology_guard.
Fixes #3907
*) streaming: Take service topology_guard under the try block
Taking the service::topology_guard could throw. Currently, it throws
outside the try block, so the rpc sink will not be closed, causing the
following assertion:
```
scylla: seastar/include/seastar/rpc/rpc_impl.hh:815: virtual
seastar::rpc::sink_impl<netw::serializer,
streaming::stream_blob_cmd_data>::~sink_impl() [Serializer =
netw::serializer, Out = <streaming::stream_blob_cmd_data>]: Assertion
`this->_con->get()->sink_closed()' failed.
```
To fix, move more code including the topology_guard taking code to the
try block.
Fixes https://github.com/scylladb/scylla-enterprise/issues/4106
Closes scylladb/scylla-enterprise#4110
*) Merge 'Preserve original SSTable state with file based tablet migration' from Raphael "Raph" Carvalho
We're not preserving the SSTable state across file based migration, so
staging SSTables for example are being placed into main directory, and
consequently, we're mixing staging and non-staging data, losing the
ability to continue from where the old replica left off.
It's expected that the view update backlog is transferred from old
into new replica, as migration doesn't wait for leaving replica to
complete view update work (which can take long). Elasticity is preferred.
So this fix guarantees that the state of the SSTable will be preserved
by propagating it in form of subdirectory (each subdirectory is
statically mapped with a particular state).
The staging sstables aren't being registered into view update generator
yet, as that's supposed to be fixed in OSS (more details can be found
at https://github.com/scylladb/scylladb/issues/19149).
Fixes #4265.
Closes scylladb/scylla-enterprise#4267
* github.com:scylladb/scylla-enterprise:
tablet: Preserve original SSTable state with file based tablet migration
sstables: Add get method for sstable state
*) sstable: (Re-)add shareabled_components getter
*) Merge 'File streaming sstables: Use sstable source/sink to transfer snapshots' from Calle Wilund
Fixes #4246
Alternative approach/better separation of concern, transport vs. sstable layer. Builds on #4472, but fancier.
Ensures we transfer and pre-process scylla metadata for streamed
file blobs first, then properly apply receiving nodes local config
by using a source and sink layer exported from sstables, which
handles things like ordering, metadata filtering (on source) as well
as handling metadata and proper IO paths when writing data on
receiver node (sink).
This implementation maintains the statelessness of the current
design, and the delegated sink side will re-read and re-write the
metadata for each component processed. This is a little wasteful,
but the meta is small, and it is less error prone than trying to do
caching cross-shards etc. The transport is isolated from the
knowledge.
This is an alternative/complement to #4436 and #4472, fixing the
underlying issue. Note that while the layers/API:s here allows easy
fixing of other fundamental problems in the feature (such as
destination location etc), these are not included in the PR, to keep
it as close to the current behaviour as possible.
Closes scylladb/scylla-enterprise#4646
* github.com:scylladb/scylla-enterprise:
raft_tests: Copy/add a topology test with encryption
file streaming: Use sstable source/sink to transfer snapshots
sstables: Add source and sink objects + producers for transfering a snapshot
sstable::types: Add remove accessor for extension info in metadata
*) The change for error injection in merge commit 966ea5955dd8760:
File streaming now has "stream_mutation_fragments" error injection points
so test_table_dropped_during_streaming works with file streaming.
*) doc: document file-based streaming
This commit adds a description of the file-based streaming feature to the documentation.
It will be displayed in the docs using the scylladb_include_flag directive after
https://github.com/scylladb/scylladb/pull/20182 is merged, backported to branch-6.0,
and, in turn, branch-2024.2.
Refs https://github.com/scylladb/scylla-enterprise/issues/4585
Refs https://github.com/scylladb/scylla-enterprise/issues/4254
Closes scylladb/scylla-enterprise#4587
*) doc: move File-based streaming to the Tablets source file-based-streaming
This commit moves the description of file-based streaming from a common include file
to the regular doc source file where tablets are described.
Closes scylladb/scylla-enterprise#4652
*) streaming: sstable_stream_sink_impl: abort: prevent null pointer dereference
Closes scylladb/scylladb#22467
Scylla unit tests using C++ and the Boost test framework
The source files in this directory are Scylla unit tests written in C++ using the Boost.Test framework. These unit tests come in three flavors:
-
Some simple tests that check stand-alone C++ functions or classes use Boost's
BOOST_AUTO_TEST_CASE. -
Some tests require Seastar features, and need to be declared with Seastar's extensions to Boost.Test, namely
SEASTAR_TEST_CASE. -
Even more elaborate tests require not just a functioning Seastar environment but also a complete (or partial) Scylla environment. Those tests use the
do_with_cql_env()ordo_with_cql_env_thread()function to set up a mostly-functioning environment behaving like a single-node Scylla, in which the test can run.
While we have many tests of the third flavor, writing new tests of this type should be reserved to white box tests - tests where it is necessary to inspect or control Scylla internals that do not have user-facing APIs such as CQL. In contrast, black-box tests - tests that can be written only using user-facing APIs, should be written in one of newer test frameworks that we offer - such as test/cqlpy or test/alternator (in Python, using the CQL or DynamoDB APIs respectively) or test/cql (using textual CQL commands), or - if more than one Scylla node is needed for a test - using the test/topology* framework.
Running tests
Because these are C++ tests, they need to be compiled before running.
To compile a single test executable row_cache_test, use a command like
ninja build/dev/test/boost/row_cache_test
You can also use ninja dev-test to build all C++ tests, or use
ninja deb-build to build the C++ tests and also the full Scylla executable
(however, note that full Scylla executable isn't needed to run Boost tests).
Replace "dev" by "debug" or "release" in the examples above and below to use the "debug" build mode (which, importantly, compiles the test with ASAN and UBSAN enabling on and helps catch difficult-to-catch use-after-free bugs) or the "release" build mode (optimized for run speed).
To run an entire test file row_cache_test, including all its test
functions, use a command like:
build/dev/test/boost/row_cache_test -- -c1 -m1G
to run a single test function test_reproduce_18045() from the longer test
file, use a command like:
build/dev/test/boost/row_cache_test -t test_reproduce_18045 -- -c1 -m1G
In these command lines, the parameters before the -- are passed to
Boost.Test, while the parameters after the -- are passed to the test code,
and in particular to Seastar. In this example Seastar is asked to run on one
CPU (-c1) and use 1G of memory (-m1G) instead of hogging the entire
machine. The Boost.Test option -t test_reproduce_18045 asks it to run just
this one test function instead of all the test functions in the executable.
Unfortunately, interrupting a running test with control-C while doesn't
work. This is a known bug (#5696). Kill a test with SIGKILL (-9) if you
need to kill it while it's running.
Boost tests can also be run using test.py - which is a script that provides a uniform way to run all tests in scylladb.git - C++ tests, Python tests, etc.
Writing tests
Because of the large build time and build size of each separate test executable, it is recommended to put test functions into relatively large source files. But not too large - to keep compilation time of a single source file (during development) at reasonable levels.
When adding new source files in test/boost, don't forget to list the new source file in configure.py and also in CMakeLists.txt. The former is needed by our CI, but the latter is preferred by some developers.