Unlike the current method (which uses consume()), this will also adjust the
initial resources, adjusting the semaphore as if it was created with the
reduced amount of resources in the first place. This fixes the confusing
90/100 count resources seen in diagnostics dump outputs.
There's a circular dependency between system_keyspace and database. The
former needs the latter because it needs to execula local requests via
query_processor. The latter needs the former via compaction manager and
large data handler, database depends on both and these too need to
insert their entries into system keyspace.
To cut this loop the compaction manager and large data handler both get
a weak reference on the system keysace. Once system keyspace starts is
activcates this reference via the database call. When system keyspace is
shutdown-ed on stop, it deactivates the reference.
Technically the weak reference is implemented by marking the system_k.s.
object as async_sharded_service, and the "reference" in question is the
shared_from_this() pointer. When compaction manager or large data
handler need to update a system keyspace's table, they both hold an
extra reference on the system keyspace until the entry is committed,
thus making sure that sys._k.s. doesn't stop from under their feet. At
the same time, unplugging the reference on shutdown makes sure that no
new entries update will appear and the system_k.s. will eventually be
released.
It's not a C++ classical reference, because system_keyspace starts after
and stops before database.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
This series adds support for detecting collections that have too many items
and recording them in `system.large_cells`.
A configuration variable was added to db/config: `compaction_collection_items_count_warning_threshold` set by default to 10000.
Collections that have more items than this threshold will be warned about and will be recorded as a large cell in the `system.large_cells` table. Documentation has been updated respectively.
A new column was added to system.large_cells: `collection_items`.
Similar to the `rows` column in system.large_partition, `collection_items` holds the number of items in a collection when the large cell is a collection, or 0 if it isn't. Note that the collection may be recorded in system.large_cells either due to its size, like any other cell, and/or due to the number of items in it, if it cross the said threshold.
Note that #11449 called for a new system.large_collections table, but extending system.large_cells follows the logic of system.large_partitions is a smaller change overall, hence it was preferred.
Since the system keyspace schema is hard coded, the schema version of system.large_cells was bumped, and since the change is not backward compatible, we added a cluster feature - `LARGE_COLLECTION_DETECTION` - to enable using it.
The large_data_handler large cell detection record function will populate the new column only when the new cluster feature is enabled.
In addition, unit tests were added in sstable_3_x_test for testing large cells detection by cell size, and large_collection detection by the number of items.
Closes#11449Closes#11674
* github.com:scylladb/scylladb:
sstables: mx/writer: optimize large data stats members order
sstables: mx/writer: keep large data stats entry as members
db: large_data_handler: dynamically update config thresholds
utils/updateable_value: add transforming_value_updater
db/large_data_handler: cql_table_large_data_handler: record large_collections
db/large_data_handler: pass ref to feature_service to cql_table_large_data_handler
db/large_data_handler: cql_table_large_data_handler: move ctor out of line
docs: large-rows-large-cells-tables: fix typos
db/system_keyspace: add collection_elements column to system.large_cells
gms/feature_service: add large_collection_detection cluster feature
test: sstable_3_x_test: add test_sstable_too_many_collection_elements
test: lib: simple_schema: add support for optional collection column
test: lib: simple_schema: build schema in ctor body
test: lib: simple_schema: cql: define s1 as static only if built this way
db/large_data_handler: maybe_record_large_cells: consider collection_elements
db/large_data_handler: debug cql_table_large_data_handler::delete_large_data_entries
sstables: mx/writer: pass collection_elements to writer::maybe_record_large_cells
sstables: mx/writer: add large_data_type::elements_in_collection
db/large_data_handler: get the collection_elements_count_threshold
db/config: add compaction_collection_elements_count_warning_threshold
test: sstable_3_x_test: add test_sstable_write_large_cell
test: sstable_3_x_test: pass cell_threshold_bytes to large_data_handler
test: sstable_3_x_test: large_data_handler: prepare callback for testing large_cells
test: sstable_3_x_test: large_data tests: use BOOST_REQUIRE_[GL]T
test: sstable_3_x_test: test_sstable_log_too_many_rows: use tests::random
make the various large data thresholds live-updateable
and construct the observers and updaters in
cql_table_large_data_handler to dynamically update
the base large_data_handler class threshold members.
Fixes#11685
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
The "virtual dirty" term is not very informative. "Virtual" means
"not real", but it doesn't say in which way it isn't real.
In this case, virtual dirty refers to real dirty memory, minus
the portion of memtables that has been written to disk (but not
yet sealed - in that case it would not be dirty in the first
place).
I chose to call "the portion of memtables that has been written
to disk" as "spooled memory". At least the unique term will cause
people to look it up and may be easier to remember. From that
we have "unspooled memory".
I plan to further change the accounting to account for spooled memory
rather than unspooled, as that is a more natural term, but that is left
for later.
The documentation, config item, and metrics are adjusted. The config
item is practically unused so it isn't worth keeping compatibility here.
Before 95f31f37c1 ("Merge 'dirty_memory_manager: simplify
region_group' from Avi Kivity"), we had two region_group
objects, one _real_region_group and another _virtual_region_group,
each with a set of "soft" and "hard" limits and related functions
and members.
In 95f31f37c1, we merged _real_region_group into _virtual_region_group,
but unfortunately the _real_region_group members received the "hard"
prefix when they got merged. This overloads the meaning of "hard" -
is it related to soft/hard limit or is it related to the real/virtual
distinction?
This patch applied some renaming to restore consistency. Anything
that came from _virtual_region_group now has "virtual" in its name.
Anything that came from _real_region_group now has "real" in its name.
The terms are still pretty bad but at least they are consistent.
For recording collection_elements of large_collections when
the large_collection_detection feature is enabled.
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
region_group evolved as a tree, each node of which contains some
regions (memtables). Each node has some constraints on memory, and
can start flushing and/or stop allocation into its memtables and those
below it when those constraints are violated.
Today, the tree has exactly two nodes, only one of which can hold memtables.
However, all the complexity of the tree remains.
This series applies some mechanical code transformations that remove
the tree structure and all the excess functionality, leaving a much simpler
structure behind.
Before:
- a tree of region_group objects
- each with two parameters: soft limit and hard limit
- but only two instances ever instantiated
After:
- a single region_group object
- with three parameters - two from the bottom instance, one from the top instance
Closes#11570
* github.com:scylladb/scylladb:
dirty_memory_manager: move third memory threshold parameter of region_group constructor to reclaim_config
dirty_memory_manager: simplify region_group::update()
dirty_memory_manager: fold region_group::notify_hard_pressure_relieved into its callers
dirty_memory_manager: clean up region_group::do_update_hard_and_check_relief()
dirty_memory_manager: make do_update_hard_and_check_relief() a member of region_group
dirty_memory_manager: remove accessors around region_group::_under_hard_pressure
dirty_memory_manager: merge memory_hard_limit into region_group
dirty_memory_manager: rename members in memory_hard_limit
dirty_memory_manager: fold do_update() into region_group::update()
dirty_memory_manager: simplify memory_hard_limit's do_update
dirty_memory_manager: drop soft limit / soft pressure members in memory_hard_limit
dirty_memory_manager: de-template do_update(region_group_or_memory_hard_limit)
dirty_memory_manager: adjust soft_limit threshold check
dirty_memory_manager: drop memory_hard_limit::_name
dirty_memory_manager: simplify memory_hard_limit configuration
dirty_memory_manager: fold region_group_reclaimer into {memory_hard_limit,region_group}
dirty_memory_manager: stop inheriting from region_group_reclaimer
dirty_memory_manager: test: unwrap region_group_reclaimer
dirty_memory_manager: change region_group_reclaimer configuration to a struct
dirty_memory_manager: convert region_group_reclaimer to callbacks
dirty_memory_manager: consolidate region_group_reclaimer constructors
dirty_memory_manager: rename {memory_hard_limit,region_group}::notify_relief
dirty_memory_manager: drop unused parameter to memory_hard_limit constructor
dirty_memory_manager: drop memory_hard_limit::shutdown()
dirty_memory_manager: split region_group hierarchy into separate classes
dirty_memory_manager: extract code block from region_group::update
dirty_memory_manager: move more allocation_queue functions out of region_group
dirty_memory_manager: move some allocation queue related function definitions outside class scope
dirty_memory_manager: move region_group::allocating_function and related classes to new class allocation_queue
dirty_memory_manager: remove support for multiple subgroups
The two classes always have a 1:1 or 0:1 relationship, and
so we can just move all the members of memory_hard_limit
into region_group, with the functions that track the relationship
(memory_hard_limit::{add,del}()) removed.
The 0:1 relationship is maintained by initializing the
hard limit parameter with std::numeric_limits<size_t>::max().
The _hard_total_memory variable is always checked if it is
greater than this parameter in order to do anything, and
with this default it can never be.
The logic to reject explicit snapshot of views/indexes
was improved in aa127a2dbb.
However, we never implemented auto-snapshot of
view/indexes when taking a snapshot of the base table.
This is implemented in this patch.
The implementation is built on top of
ba42852b0e
so it would be hard to backport to 5.1 or earlier
releases.
Fixes#11612
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
When querier read page with tombstones more than `tombstone_warn_threshold` limit - warning message appeared in logs.
If `tombstone_warn_threshold:0` feature disabled.
Refs scylladb#11410
We observe that memory_hard_limit's reclaim_config is only ever
initialized as default, or with just the hard_limit parameter.
Since soft_limit defaults to hard_limit, we can collapse the two
into a limit. The reclaim callbacks are always left as the default
no-op functions, so we can eliminate them too.
This fits with memory_hard_limit only being responsible for the hard
limit, and for it not having any memtables to reclaim on its own.
region_group_reclaimer is used to initialize (by reference) instances of
memory_hard_limit and region_group. Now that it is a final class, we
can fold it into its users by pasting its contents into those users,
and using the initializer (reclaim_config) to initialize the users. Note
there is a 1:1 relationship between a region_group_reclaimer instance
and a {memory_hard_limit,region_group} instance.
It may seem like code duplication to paste the contents of one class into
two, but the two classes use region_group_reclaimer differently, and most
of the code is just used to glue different classes together, so the
next patches will be able to get rid of much of it.
Some notes:
- no_reclaimer was replaced by a default reclaim_config, as that's how
no_reclaimer was initialized
- all members were added as private, except when a caller required one
to be public
- an under_presssure() member already existed, forwarding to the reclaimer;
this was just removed.
This inheritance makes it harder to get rid of the class. Since
there are no longer any virtual functions in the class (apart from
the destructor), we can just convert it to a data member. In a few
places, we need forwarding functions to make formerly-inherited functions
visible to outside callers.
The virtual destructor is removed and the class is marked final to
verify it is no longer a base class anywhere.
It's just so much nicer.
The "threshold" limit was renamed to "hard_limit" to contrast it with
"soft_limit" (in fact threshold is a good name for soft_limit, since
it's a point where the behavior begins to change, but that's too much
of a change).
region_group_reclaimer is partially policy (deciding when to reclaim)
and partially mechanism (implementing reclaim via virtual functions).
Move the mechanism to callbacks. This will make it easy to fold the
policy part into region_group and memory_hard_limit. This folding is
expected to simplify things since most of region_group_reclaimer is
cross-class communication.
Introduces support to split large partitions during compaction. Today, compaction can only split input data at partition boundary, so a large partition is stored in a single file. But that can cause many problems, like memory pressure (e.g.: https://github.com/scylladb/scylladb/issues/4217), and incremental compaction can also not fulfill its promise as the file storing the large partition can only be released once exhausted.
The first step was to add clustering range metadata for first and last partition keys (retrieved from promoted index), which is crucial to determine disjointness at clustering level, and also the order at which the disjoint files should be opened for incremental reading.
The second step was to extend sstable_run to look at clustering dimension, so a set of files storing disjoint ranges for the same partition can live in the same sstable run.
The final step was to introduce the option for compaction to split large partition being written if it has exceeded the size threshold.
What's next? Following this series, a reader will be implemented for sstable_run that will incrementally open the readers. It can be safely built on the assumption of the disjoint invariant after the second step aforementioned.
Closes#11233
* github.com:scylladb/scylladb:
test: Add test for large partition splitting on compaction
compaction: Add support to split large partitions
sstable: Extend sstable_run to allow disjointness on the clustering level
sstables: simplify will_introduce_overlapping()
test: move sstable_run_disjoint_invariant_test into sstable_datafile_test
test: lib: Fix inefficient merging of mutations in make_sstable_containing()
sstables: Keep track of first partition's first pos and last partition's last pos
sstables: Rename min/max position_range to a descriptive name
sstables_manager: Add sstable metadata reader concurrency semaphore
sstables: Add ability to find first or last position in a partition
Let's introduce a reader_concurrency_semaphore for reading sstable
metadata, to avoid an OOM due to unlimited concurrency.
The concurrency on startup is not controlled, so it's important
to enforce a limit on the amount of memory used by the parallel
readers.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
The intention was for these logs to be printed during the
database shutdown sequence, but it was overlooked that it's not
the only place where commitlog::shutdown is called.
Commitlogs are started and shut down periodically by hinted handoff.
When that happens, these messages spam the log.
Fix that by adding INFO commitlog shutdown logs to database::stop,
and change the level of the commitlog::shutdown log call to DEBUG.
Fixes#11508Closes#11536
and use it to access the repair history maps.
At this introductory patch, we use default-constructed
tombstone_gc_state to access the thread-local maps
temporarily and those use sites will be replaced
in following patches that will gradually pass
the tombstone_gc_state down from the compaction_manager
to where it's used.
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
drop_repair_history_map_for_table is called on each shard
when database::truncate is done, and the table is stopped.
dropping it before the table is stopped is too early.
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
These are pretend free functions, accessing globals in the background,
make them a member of the tracker instead, which everything needed
locally to compute them. Callers still have to access these stats
through the global tracker instance, but this can be changed to happen
through a local instance. Soon....
Instead of querier_cache::evict_all_for_table(). The new method cover
all queriers and in addition any other inactive reads registered on the
semaphore. In theory by the time we detach a table, no regular inactive
reads should be in the semaphore anymore, but if there is any still, we
better evict them before the table is destroyed, they might attempt to
access it in when destroyed later.
Many tombstones in a partition is a problem that has been plaguing queries since the inception of Scylla (and even before that as they are a pain in Apache Cassandra too). Tombstones don't count towards the query's page limit, neither the size nor the row number one. Hence, large spans of tombstones (be that row- or range-tombstones) are problematic: the query can time out while processing this span of tombstones, as it waits for more live rows to fill the page. In the extreme case a partition becomes entirely unreadable, all read attempts timing out, until compaction manages to purge the tombstones.
The solution proposed in this PR is to pass down a tombstone limit to replicas: when this limit is reached, the replica cuts the page and marks it as short one, even if the page is empty currently. To make this work, we use the last-position infrastructure added recently by 3131cbea62, so that replicas can provide the position of the last processed item to continue the next page from. Without this no forward progress could be made in the case of an empty page: the query would continue from the same position on the next page, having to process the same span of tombstones.
The limit can be configured with the newly added `query_tombstone_limit` configuration item, defaulted to 10000. The coordinator will pass this to the newly added `tombstone_limit` field of `read_command`, if the `replica_empty_pages` cluster feature is set.
Upgrade sanity test was conducted as following:
* Created cluster of 3 nodes with RF=3 with master version
* Wrote small dataset of 1000 rows.
* Deleted prefix of 980 rows.
* Started read workload: `scylla-bench -mode=read -workload=uniform -replication-factor=3 -nodes 127.0.0.1,127.0.0.2,127.0.0.3 -clustering-row-count=10000 -duration=10m -rows-per-request=9000 -page-size=100`
* Also did some manual queries via `cqlsh` with smaller page size and tracing on.
* Stopped and upgraded each node one-by-one. New nodes were started by `--query-tombstone-page-limit=10`.
* Confirmed there are no errors or read-repairs.
Perf regression test:
```
build/release/test/perf/perf_simple_query_g -c1 -m2G --concurrency=1000 --task-quota-ms 10 --duration=60
```
Before:
```
median 133665.96 tps ( 62.0 allocs/op, 12.0 tasks/op, 43007 insns/op, 0 errors)
median absolute deviation: 973.40
maximum: 135511.63
minimum: 104978.74
```
After:
```
median 129984.90 tps ( 62.0 allocs/op, 12.0 tasks/op, 43181 insns/op, 0 errors)
median absolute deviation: 2979.13
maximum: 134538.13
minimum: 114688.07
```
Diff: +~200 instruction/op.
Fixes: https://github.com/scylladb/scylla/issues/7689
Fixes: https://github.com/scylladb/scylla/issues/3914
Fixes: https://github.com/scylladb/scylla/issues/7933
Refs: https://github.com/scylladb/scylla/issues/3672Closes#11053
* github.com:scylladb/scylladb:
test/cql-pytest: add test for query tombstone page limit
query-result-writer: stop when tombstone-limit is reached
service/pager: prepare for empty pages
service/storage_proxy: set smallest continue pos as query's continue pos
service/storage_proxy: propagate last position on digest reads
query: result_merger::get() don't reset last-pos on short-reads and last pages
query: add tombstone-limit to read-command
service/storage_proxy: add get_tombstone_limit()
query: add tombstone_limit type
db/config: add config item for query tombstone limit
gms: add cluster feature for empty replica pages
tree: don't use query::read_command's IDL constructor
This series converts the synchronous `effective_replication_map::get_range_addresses` to async
by calling the replication strategy async entry point with the same name, as its callers are already async
or can be made so easily.
To allow it to yield and work on a coherent view of the token_metadata / topology / replication_map,
let the callers of this patch hold a effective_replication_map per keyspace and pass it down
to the (now asynchronous) functions that use it (making affected storage_service methods static where possible
if they no longer depend on the storage_service instance).
Also, the repeated calls to everywhere_replication_strategy::calculate_natural_endpoints
are optimized in this series by introducing a virtual abstract_replication_strategy::has_static_natural_endpoints predicate
that is true for local_strategy and everywhere_replication_strategy, and is false otherwise.
With it, functions repeatedly calling calculate_natural_endpoints in a loop, for every token, will call it only once since it will return the same result every time anyhow.
Refs #11005
Doesn't fix the issue as the large allocation still remains until we make change dht::token_range_vector chunked (chunked_vector cannot be used as is at the moment since we require the ability to push also to the front when unwrapping)
Closes#11009
* github.com:scylladb/scylladb:
effective_replication_map: make get_range_addresses asynchronous
range_streamer: add_ranges and friends: get erm as param
storage_service: get_new_source_ranges: get erm as param
storage_service: get_changed_ranges_for_leaving: get erm as param
storage_service: get_ranges_for_endpoint: get erm as param
repair: use get_non_local_strategy_keyspaces_erms
database: add get_non_local_strategy_keyspaces_erms
database: add get_non_local_strategy_keyspaces
storage_service: coroutinize update_pending_ranges
effective_replication_map: add get_replication_strategy
effective_replication_map: get_range_addresses: use the precalculated replication_map
abstract_replication_strategy: get_pending_address_ranges: prevent extra vector copies
abstract_replication_strategy: reindent
utils: sequenced_set: expose set and `contains` method
abstract_replication_strategy: calculate_natural_endpoints: return endpoint_set
utils: sequenced_set: templatize VectorType
utils: sanitize sequenced_set
utils: sequenced_set: delete mutable get_vector method
To be used by coordinator side code to determine the correct tombstone
limit to pass to read-command (tombstone limit field added in the next
commit). When this limit is non-zero, the replica will start cutting
pages after the tombstone limit is surpassed.
This getter works similarly to `get_max_result_size()`: if the cluster
feature for empty replica pages is set, it will return the value
configured via db::config::query_tombstone_limit. System queries always
use a limit of 0 (unlimited tombstones).
To be used for getting a coheret set of all keyspaces
with non-local replication strategy and their respective
effective_replication_map.
As an example, use it in this patch in
storage_service::update_pending_ranges.
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
For node operations, we currently call get_non_system_keyspaces
but really want to work on all keyspace that have non-local
replication strategy as they are replicated on other nodes.
Reflect that in the replica::database function name.
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
Define table_schema_version as a distinct tagged_uuid class,
So it can be differentiated from other uuid-class types,
in particular table_id.
Added reversed(table_schema_version) for convenience
and uniformity since the same logic is currently open coded
in several places.
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
Define table_id as a distinct utils::tagged_uuid modeled after raft
tagged_id, so it can be differentiated from other uuid-class types,
in particular from table_schema_version.
Fixes#11207
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
Pass an optional truncated_at time_point to
truncate_table_on_all_shards instead of the over-complicated
timestamp_func that returns the same time_point on all shards
anyhow, and was only used for coordination across shards.
Since now we synchronize the internal execution phase in
truncate_table_on_all_shards, there is no longer need
for this timestamp_func.
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
With that the database layer does no longer
need to invoke the private table::snapshot function,
so it can be defriended from class table.
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
Start moving the per-shard state establishment logic
to truncate_table_on_all_shards, so that we would evetually
do only the truncate logic per-se in the per-shard truncate function.
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
Now that the per-shard truncate function is called
only from truncate_table_on_all_shards, we can reject the schema_tables
keyspace in the upper layer. There's no need to check that on each shard.
While at it, reuse `is_system_keyspace`.
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
Called from the respective database entry points.
Will be called also from the database drop / truncate path
and will be used for central coordination of per-shard
table::snapshot so we don't have to depend on the snapshot_manager
mechanism that is fragile and currently causes abort if we fail
to allocate it.
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
