Add a boolean to short circuit the read path on empty range
hoping for some speedup.
tested in read write with cs using:
cl=QUORUM duration=1m -mode native cql3 -rate threads=700 -node localhost
Will do some additional benchmark.
Fixes#1056
Signed-off-by: Benoît Canet <benoit@scylladb.com>
Message-Id: <20170118194451.16836-1-benoit@scylladb.com>
Currently eviction is performed until occupancy of the whole region
drops below the 85% threshold. This may take a while if region had
high occupancy and is large. We could improve the situation by only
evicting until occupancy of the sparsest segment drops below the
threshold, as is done by this change.
I tested this using a c-s read workload in which the condition
triggers in the cache region, with 1G per shard:
lsa-timing - Reclamation cycle took 12.934 us.
lsa-timing - Reclamation cycle took 47.771 us.
lsa-timing - Reclamation cycle took 125.946 us.
lsa-timing - Reclamation cycle took 144356 us.
lsa-timing - Reclamation cycle took 655.765 us.
lsa-timing - Reclamation cycle took 693.418 us.
lsa-timing - Reclamation cycle took 509.869 us.
lsa-timing - Reclamation cycle took 1139.15 us.
The 144ms pause is when large eviction is necessary.
The change improves worst case latency. Reclamation time statistics
over 30 second period after cache fills up, in microseconds:
Before:
avg = 1524.283148
stdev = 11021.021118
min = 12.934000
max = 144356.000000
sum = 257603.852000
samples = 169
After:
avg = 1317.362414
stdev = 1913.542802
min = 263.935000
max = 19244.600000
sum = 175209.201000
samples = 133
Refs #1634.
Message-Id: <1484730859-11969-1-git-send-email-tgrabiec@scylladb.com>
Since ce083308a1
"random_mutation_generator: Generate RTs by default" random mutation
generator produces range tombstones. However, so far the tests were run
with all features disabled (because of incomplete initialization of all
services) which meant that RANGE_TOMBSTONE feature was not enabled and
the code couldn't handle range tombstones that weren't just prefixes.
This patch solves the problem by forcing all features to be enabled when
tests are run.
Message-Id: <20170116103324.22956-1-pdziepak@scylladb.com>
This patch changes the random_mutation_generator so it generates range
tombstones by default. This fixes a bug where reversibly applying
range tombstones wasn't being tested.
Signed-off-by: Duarte Nunes <duarte@scylladb.com>
Message-Id: <20170110164822.28747-1-duarte@scylladb.com>
"Intended to reduce memory usage when resharding by sharing sstable
components among shards. File descriptors are also shared from now
on, meaning that a much smaller number of file descriptors will be
used during resharding.
Fixes #1951."
branch 'excessive_memory_usage_v4' of github.com:raphaelsc/scylla
* 'excessive_memory_usage_v4' of github.com:raphaelsc/scylla:
db: avoid excessive memory usage during resharding
checked_file_impl: add support to dup
sstables: group sstable components that can be shared among shards
sstables: rename sstable member
After resharding, sstables may be owned by all shards, which
means that file descriptors and memory usage for metadata will
increase by a factor equal to number of shards. That can easily
lead to OOM.
SSTable components are immutable, so they can be stored in one
shard and shared with others that need it. We use the following
formula to decide which shard will open the sstable and share
it with the others: (generation % smp::count), which is the
inverse of how we calculate generation for new sstables.
So if no resharding is performed, everything is shard-local.
With this approach, resource usage due to loaded sstables will
be evenly distributed among shards.
For this approach to work, we now only populate keyspaces from
shard 0. It's now the sole responsible for iterating through
column family dirs. In addition, most of population functions
are now free and take distributed database object as parameter.
Fixes#1951.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
"This patch series adds support for CQL 3.3.1. The changes to CQL are listed
here:
https://github.com/apache/cassandra/blob/cassandra-2.2/doc/cql3/CQL.textile#changes
The following CQL features are already supported by Scylla:
- TRUNCATE TABLE alias
- Double-dollar string literals
- Aggregate functions: MIN, MAX, SUM, and AVG
This series adds the following CQL features:
- New data types: tinyint, smallint, date, and time
- CQL binary protocol v4 (required by the new data types)
- Advertise Cassandra 2.2.8 version from Scylla so that drivers correctly
detect the presence of CQL 3.3.1
The following CQL features are not supported by Scylla:
- Role-based access control (issue #1941)
- JSON data type
- User-defined functions (UDFs)
- User-defined aggregates (UDAs)
The following CQL binary protocol v4 changes are not implemented by this
series:
- Read_failure and Write_failure error codes are not implemented.
They error codes not used by the smart drivers but as they are
propagated to application code, we eventually need to wire them up
to our storage proxy implementation.
- Function_failure error code is only used by user-defined functions
and the fromJson function, which are not implemented by Scylla.
Fixes #1284."
* 'penberg/cql-3.3.1/v5' of github.com:cloudius-systems/seastar-dev:
version: Bump Cassandra version to 2.2.8
db/schema_tables: Add schema_functions and schema_aggregates tables
tests/type_tests: TIME type test cases
tests/cql_query_test: TIME type test cases
cql3: TIME data type support
tests/type_tests: DATE type test cases
tests/cql_query_test: DATE type test cases
cql3: DATE type support
date.h: 64-bit year and days representation
licenses: Add utils/date.h license
utils/date.h: Import date and time library sources
tests/type_tests: TINYINT and SMALLINT type test cases
tests/cql_query_test: TINYINT and SMALLINT type test cases
cql3: TINYINT and SMALLINT data type support
types: Fix integer_type_impl::parse_int() for bytes
We intend to share immutable sstable components among shards to
reduce excessive memory usage when resharding shared sstables.
This change is about grouping those components into a structure,
and using foreign ptr to make sure that the structure will be
deleted by whichever shard created it.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
Rename _components to _recognized_components because _components
will be used to name a field with shareable components.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
"Reduce the size of mutation_partition by implementing intrusive set using
bi::rbtree_algorithms directly and using tree nodes optimized for size.
This will reduce the size of mutation_partition by:
24 bytes + <number of cql rows> * 8 bytes
This should have a positive impact on performance because mutation_partitions
are stored both in memtable and cache.
Fixes #742."
* 'haaawk/742' of github.com:cloudius-systems/seastar-dev:
intrusive_set: rename size() to calculate_size()
Make intrusive_set_external_comparator::_value_traits static
Implement intrusive set using rbtree_algorithms
mutation_partition: make apply_reversibly_intrusive_set nongeneric
mutation_partition: take schema in find_row and clustered_row
mutation_partition: Extract intrusive set logic to a class.
mutation_partition: Replace value_comp with key_comp calls
This hopefully will make it more apparent that
the time complexity of this method is O(N) not O(1).
Signed-off-by: Piotr Jastrzebski <piotr@scylladb.com>
The test case is interested in the upper boundary of 32-bit integer
because we already test the lower boundary in assertions below. The old
test passed, of course, but it wasn't very interesting.
Message-Id: <1483522773-6008-1-git-send-email-penberg@scylladb.com>
"This patchset contains fixes for the changes introduced in "Query result
size limiting". It also improves handling of short data reads.
I order to minimise chances of digest mismatch during data queries replicas
that were asked just to return a digest also keep track of the size of the
data (in the IDL representation) so that they would stop at the same point
nodes doing full data queries would. Moreover, data queries are not
affected by per-shard memory limit and the coordinator sends individual
result size limits to replicas in order not to depend on hardcoded values.
It is still possible to get digest mismatches if the IDL changes (e.g. a
new field is added), but, hopefully, that won't be a serious problem."
* 'pdziepak/short-read-fixes/v4' of github.com:cloudius-systems/seastar-dev:
query: introduce result_memory_accounter::foreign_state
storage_proxy: fix short reads in parallel range queries
storage_proxy: pass maximum result size to replicas
mutation_partition: use result limiter for digest reads
query: make result_memory_limiter constants available for linker
result_memory_limiter: add accounter for digest reads
idl: allow writers to use any output stream
result_memory_limiter: split new_read() to new_{data, mutation}_read()
idl: is_short_read() was added in 1.6
mutation_partition: honour allowed_short_read for static rows
storage_proxy: fix _is_short_read computation
storage_proxy: disallow short reads if got no live rows
storage_proxy: don't stop after result with no live rows
This reverts commit aa392810ff, reversing
changes made to a24ff47c637e6a5fd158099b8a65f1191fc2d023; it uses
boost::intrusive::detail directly, which it must not, and doesn't compile on
all boost versions as a consequence.
"Reduce the size of mutation_partition by implementing intrusive set using
bi::rbtree_algorithms directly and using tree nodes optimized for size.
This will reduce the size of mutation_partition by:
24 bytes + <number of cql rows> * 8 bytes
This should have a positive impact on performance because mutation_partitions
are stored both in memtable and cache.
Fixes #742."
* 'haaawk/742' of github.com:cloudius-systems/seastar-dev:
intrusive_set: rename size() to calculate_size()
Make intrusive_set_external_comparator::_value_traits static
Implement intrusive set using rbtree_algorithms
mutation_partition: make apply_reversibly_intrusive_set nongeneric
mutation_partition: take schema in find_row and clustered_row
mutation_partition: Extract intrusive set logic to a class.
mutation_partition: Replace value_comp with key_comp calls
This hopefully will make it more apparent that
the time complexity of this method is O(N) not O(1).
Signed-off-by: Piotr Jastrzebski <piotr@scylladb.com>
We may want to change the default individual result size limit in the
future. If it is provided by the coordinator and not hardcoded in the
replicas this can be done without causing data query digest mismatches
or wasteful mutation query results.
Original IDL generated code was hardcoded to always use bytes_ostream.
This patch makes the output stream a template parameter so that any
valid output stream can be used.
Unfortunately, making IDL writers generic requires updates in the code
that uses them, this is fixed in C++17 which would be able to deduce the
parameter in most cases.
- moved to seastar thread
- extracted sstable creation and validation logic
- reduced code duplication
- switched to mutation_reader assertions
- used result of compact_sstable() to locate the new sstable
- rather than setting gc timestamp in the past, bump the clock
before compacting
Refs #1943.
* 'tgrabiec/optimize-bloom-filter' of github.com:cloudius-systems/seastar-dev:
db: Compute key hash once in partition_presence_checker
bloom_filter: Allow checking presence using pre-hashed key
db: Use incremental selector in partition_presence_checker
This patch adds a set of tests for materialized view schema
handling, complementing the dtests for the same feature.
Signed-off-by: Duarte Nunes <duarte@scylladb.com>
This patch introduces the do_with_cql_env_thread() function, which
behaves like do_with_cql_env() except that it executes the
user-specified function in the context of a Seastar thread.
Signed-off-by: Duarte Nunes <duarte@scylladb.com>
This reduces the number of sstables we need to check to only those
whose token range overlaps with the key. Reduces cache update
time. Especially effective with leveled compaction strategy.
Refs #1943.
Incremental selector works with an immutable sstable set, so cache
updates need to be serialized. Otherwise we could mispopulate due to
stale presence information.
Presence checker interface was changed to accept decorated key in
order to gain easy access to the token, which is required by
the incremental selector.
The test assumed that mutations added to the commitlog are visible to
reads as soon as a new segment is opened. That's not true because
buffers are written back in the background, and new segment may be
active while the previous one is still being written or not yet
synced.
Fix the test so that it expectes that the number of mutations read
this way is <= the number of mutations read, and that after all
segments are synced, the number of mutations read is equal.
Message-Id: <1481630481-19395-1-git-send-email-tgrabiec@scylladb.com>
Issue #1918 describes a problem, in which we are generating smaller
memtables than we could, and therefore not respecting the flush
criteria.
That happens because group sizes (and limits) for pressure purposes, and
the the soft threshold is currently at 40 %. This causes system group's
soft threshold to be way below regular's virtual dirty limit and close
to regular group's soft threshold. The system group was very likely to
become under soft pressure when regular was because writes to regular
group are not yet throttled when they cross both soft thresholds.
This is a direct consequence of the linear hierarchy between the regions
and to guarantee that it won't happen we would have acqire the semaphore
of all ancestor regions when flushing from a child region. While that
works, it can lead to problems on its own, like priority inversion if
the regions have different priorities - like streaming and regular, and
groups lower in the hierarchy, like user, blocking explicit flushes
from their ancestors
To fix that, this patch reorganizes the dirty memory region groups so
that groups are now completely independent. As a disadvantage, when
streaming happen we will draw some memory from the cache, but we will
live with it for the time being.
Fixes#1918
Signed-off-by: Glauber Costa <glauber@scylladb.com>
When row cache is disabled, update_cache() will do nothing to the
memtable. Active readers may keep the memtable alive for unbounded
amount of time, preventing it from going away. This doesn't play well
with virtual dirty accounting. Soon before calling update_cache(), the
memory which was subtracted during flush is added back to the amount
of virtual dirty memory. If there was write pressure all along, we
will be at the dirty memory limit. When we give back subtracted memory
this will put virtual dirty way above the limit. This will stall all
writes until another memtable flush drags virtual dirty down or
readers finally release the memtable. We want to prevent upward
jumps of virtual dirty.
First part of the fix is to ensure that as long as the memtable's
region is in the dirty group, we will not revert flushed memory. This
must happen synchronously from region's memory being removed from the
group in order to prevent upward virtual dirty jumps. To make this
easier, tracking of flushed memory was moved to the memtable object.
Another part of the fix is to gradually clear the memtable when cache
is disabled in a similar fashion as when it's moved to cache. This
ensures that the actual memory held by memtable's region is released
sooner than it dies.
Refs #1879
The implementation assumes that memtable's region group is owned by
dirty_memory_manager, and tries to obtain a reference to it like this:
boost::intrusive::get_parent_from_member(_region.group(), &dirty_memory_manager::_region_group));
This is undefined behavior when the region's group does not come from
dirty manager. It's safer to be explicit about this dependency by
taking a reference to dirty_memory_manager in the constructor.
