The flat_mutation_reader files were conflated and contained multiple
readers, which were not strictly necessary. Splitting optimizes both
iterative compilation times, as touching rarely used readers doesn't
recompile large chunks of codebase. Total compilation times are also
improved, as the size of flat_mutation_reader.hh and
flat_mutation_reader_v2.hh have been reduced and those files are
included by many file in the codebase.
With changes
real 29m14.051s
user 168m39.071s
sys 5m13.443s
Without changes
real 30m36.203s
user 175m43.354s
sys 5m26.376s
Closes#10194
Memtables are a replica-side entity, and so are moved to the
replica module and namespace.
Memtables are also used outside the replica, in two places:
- in some virtual tables; this is also in some way inside the replica,
(virtual readers are installed at the replica level, not the
cooordinator), so I don't consider it a layering violation
- in many sstable unit tests, as a convenient way to create sstables
with known input. This is a layering violation.
We could make memtables their own module, but I think this is wrong.
Memtables are deeply tied into replica memory management, and trying
to make them a low-level primitive (at a lower level than sstables) will
be difficult. Not least because memtables use sstables. Instead, we
should have a memtable-like thing that doesn't support merging and
doesn't have all other funky memtable stuff, and instead replace
the uses of memtables in sstable tests with some kind of
make_flat_mutation_reader_from_unsorted_mutations() that does
the sorting that is the reason for the use of memtables in tests (and
live with the layering violation meanwhile).
Test: unit (dev)
Closes#10120
Not a completely mechanical transition. The consumer has to generate its
mutation via a mutation_rebuilder_v2 as mutation fragment v2 cannot be
applied to mutations directly yet.
Instead of lengthy blurbs, switch to single-line, machine-readable
standardized (https://spdx.dev) license identifiers. The Linux kernel
switched long ago, so there is strong precedent.
Three cases are handled: AGPL-only, Apache-only, and dual licensed.
For the latter case, I chose (AGPL-3.0-or-later and Apache-2.0),
reasoning that our changes are extensive enough to apply our license.
The changes we applied mechanically with a script, except to
licenses/README.md.
Closes#9937
Move replica-oriented classes to the replica namespace. The main
classes moved are ::database, ::keyspace, and ::table, but a few
ancillary classes are also moved. There are certainly classes that
should be moved but aren't (like distributed_loader) but we have
to start somewhere.
References are adjusted treewide. In many cases, it is obvious that
a call site should not access the replica (but the data_dictionary
instead), but that is left for separate work.
scylla-gdb.py is adjusted to look for both the new and old names.
The database, keyspace, and table classes represent the replica-only
part of the objects after which they are named. Reading from a table
doesn't give you the full data, just the replica's view, and it is not
consistent since reconciliation is applied on the coordinator.
As a first step in acknowledging this, move the related files to
a replica/ subdirectory.
Add schema parameter so that:
* Caller has better control over schema -- especially relevant for
reverse reads where it is not possible to follow the convention of
passing the query schema which is reversed compared to that of the
mutations.
* Now that we don't depend on the mutations for the schema, we can lift
the restriction on mutations not being empty: this leads to safer
code. When the mutations parameter is empty, an empty reader is
created.
Add "make_" prefix to follow convention of similar reader factory
functions.
Tests: unit(dev)
Signed-off-by: Botond Dénes <bdenes@scylladb.com>
Message-Id: <20211115155614.363663-1-bdenes@scylladb.com>
It's easy to forget about supplying the correct value for a parameter
when it has a default value specified. It's safer if 'production code'
is forced to always supply these parameters manually.
The default values were mostly useful in tests, where some parameters
didn't matter that much and where the majority of uses of the class are.
Without default values adding a new parameter is a pain, forcing one to
modify every usage in the tests - and there are a bunch of them. To
solve this, we introduce a new constructor which requires passing the
`for_tests` tag, marking that the constructor is only supposed to be
used in tests (and the constructor has an appropriate comment). This
constructor uses default values, but the other constructors - used in
'production code' - do not.
Use a forward declaration of cql3::expr::oper_t to reduce the
number of translation units depending on expression.hh.
Before:
$ find build/dev -name '*.d' | xargs cat | grep -c expression.hh
272
After:
$ find build/dev -name '*.d' | xargs cat | grep -c expression.hh
154
Some translation units adjust their includes to restore access
to required headers.
Closes#9229
This patch flips two "switches":
1) It switches admission to be up-front.
2) It changes the admission algorithm.
(1) by now all permits are obtained up-front, so this patch just yanks
out the restricted reader from all reader stacks and simultaneously
switches all `obtain_permit_nowait()` calls to `obtain_permit()`. By
doing this admission is now waited on when creating the permit.
(2) we switch to an admission algorithm that adds a new aspect to the
existing resource availability: the number of used/blocked reads. Namely
it only admits new reads if in addition to the necessary amount of
resources being available, all currently used readers are blocked. In
other words we only admit new reads if all currently admitted reads
requires something other than CPU to progress. They are either waiting
on I/O, a remote shard, or attention from their consumers (not used
currently).
We flip these two switches at the same time because up-front admission
means cache reads now need to obtain a permit too. For cache reads the
optimal concurrency is 1. Anything above that just increases latency
(without increasing throughput). So we want to make sure that if a cache
reader hits it doesn't get any competition for CPU and it can run to
completion. We admit new reads only if the read misses and has to go to
disk.
Another change made to accommodate this switch is the replacement of the
replica side read execution stages which the reader concurrency
semaphore as an execution stage. This replacement is needed because with
the introduction of up-front admission, reads are not independent of
each other any-more. One read executed can influence whether later reads
executed will be admitted or not, and execution stages require
independent operations to work well. By moving the execution stage into
the semaphore, we have an execution stage which is in control of both
admission and running the operations in batches, avoiding the bad
interaction between the two.
Currently `cql_test_env` runs its `func` in the default (main) group and
also leaves all scheduling groups in `dbcfg` default initialized to the
same scheduling group. This results in every part of the system,
normally isolated from each other, running in the same (default)
scheduling group. Not a big problem on its own, as we are talking about
tests, but this creates an artificial difference between the test and
the real environment, which is ever more pronounced since certain query
parameters are selected based on the current scheduling group.
To bring cql test env just that little bit closer to the real thing,
this patch creates all the scheduling groups main does (well almost) and
configures `dbcfg` with them.
Creating and destroying the scheduling group on each setup-teardown of
cql test env breaks some internal seastar components which don't like
seeing the same scheduling group with the same name but different id. So
create the scheduling groups once on first access and keep them around
until the test executable is running.
Signed-off-by: Botond Dénes <bdenes@scylladb.com>
Message-Id: <20210514141614.128213-2-bdenes@scylladb.com>
Currently `with_cql_test_env()` is equivalent to
`with_cql_test_env_thread()`, which resulted in many tests using the
former while really needing the latter and getting away with it. This
equivalence is incidental and will go away soon, so make sure all cql
test env using tests that expect to be run in a thread use the
appropriate variant.
Signed-off-by: Botond Dénes <bdenes@scylladb.com>
Message-Id: <20210514141614.128213-1-bdenes@scylladb.com>
In addition to clear_inactive_reads, that's currently called when
the database object is destroyed, introduce a stop() method that will:
1. wait on all background closes of inactive_reads.
2. close all present inactive_reads and waits on their close.
3. signal waiters on the wait_list via broken() with a proper
exception indicating that the semaphore was closed.
In addition, assert in the semaphore's destructor
that it has no remaining inactive reads.
Stop must be called from whoever owns the r_c_s.
Mainly, from database::stop.
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
Failures in this test typically happen inside the test consumer object.
These however don't stop the test as the code invoking the consumer
object handles exceptions coming from it. So the test will run to
completion and will fail again when comparing the produced output with
the expected one. This results in distracting failures. The real problem
is not the difference in the output, but the first check that failed,
which is however buried in the noise. To prevent this add an "ok" flag
which is set to false if the consumer fails. In this case the additional
checks are skipped in the end to not generate useless noise.
Signed-off-by: Botond Dénes <bdenes@scylladb.com>
Message-Id: <20210326083147.26113-2-bdenes@scylladb.com>
Said test has two separate logical readers, but they share the same
permit, which is illegal. This didn't cause any problems yet, but soon
the semaphore will start to keep score of active/inactive permits which
will be confused by such sharing, so have them use separate permits.
Signed-off-by: Botond Dénes <bdenes@scylladb.com>
Message-Id: <20210326083147.26113-1-bdenes@scylladb.com>
Add a string describing where the sstables originated
from (e.g. memtable, repair, streaming, compaction, etc.)
If configure_writer is called with a nullptr, the origin
will be equal to an empty string.
Introduce test_env_sstables_manager that provides an overload
of configure_writer with no parmeters that calls the base-class'
configure_writer with "test" origin. This was to reduce the
code churn in this patch and to keep the tests simple.
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
Use the thread_local seastar::testing::local_random_engine
in all seastar tests so they can be reproduced using
the --random-seed option.
Test: unit(dev)
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
Message-Id: <20210112103713.578301-2-bhalevy@scylladb.com>
Require a schema and an operation name to be given to each permit when
created. The schema is of the table the read is executed against, and
the operation name, which is some name identifying the operation the
permit is part of. Ideally this should be different for each site the
permit is created at, to be able to discern not only different kind of
reads, but different code paths the read took.
As not all read can be associated with one schema, the schema is allowed
to be null.
The name will be used for debugging purposes, both for coredump
debugging and runtime logging of permit-related diagnostics.
We want to start tracking the memory consumption of mutation fragments.
For this we need schema and permit during construction, and on each
modification, so the memory consumption can be recalculated and pass to
the permit.
In this patch we just add the new parameters and go through the insane
churn of updating all call sites. They will be used in the next patch.
Not used yet, this patch does all the churn of propagating a permit
to each impl.
In the next patch we will use it to track to track the memory
consumption of `_buffer`.
The test consumes all resources off the semaphore, leaving just enough
to admit a single reader. However this amount is calculated based on the
base cost of readers, but as we are going to track reader buffers as
well, the amount of memory consumed will be much less predictable.
So to make sure background readers can finish during shutdown, release
all the consumed resources before leaving scope.
No point in continuing processing the entire buffer once a failure was
found. Especially that an early failure might introduce conditions that
are not handled in the normal flow-path. We could handle these but there
is no point in this added complexity, at this point the test is failed
anyway.
Currently, sstable_manager is used to create sstables, but it loses track
of them immediately afterwards. This series makes an sstable's life fully
contained within its sstable_manager.
The first practical impact (implemented in this series) is that file removal
stops being a background job; instead it is tracked by the sstable_manager,
so when the sstable_manager is stopped, you know that all of its sstable
activity is complete.
Later, we can make use of this to track the data size on disk, but this is not
implemented here.
Closes#7253
* github.com:scylladb/scylla:
sstables: remove background_jobs(), await_background_jobs()
sstables: make sstables_manager take charge of closing sstables
test: test_env: hold sstables_manager with a unique_ptr
test: drop test_sstable_manager
test: sstables::test_env: take ownership of manager
test: broken_sstable_test: prepare for asynchronously closed sstables_manager
test: sstable_utils: close test_env after use
test: sstable_test: dont leak shared_sstable outside its test_env's lifetime
test: sstables::test_env: close self in do_with helpers
test: perf/perf_sstable.hh: prepare for asynchronously closed sstables_manager
test: view_build_test: prepare for asynchronously closed sstables_manager
test: sstable_resharding_test: prepare for asynchronously closed sstables_manager
test: sstable_mutation_test: prepare for asynchronously closed sstables_manager
test: sstable_directory_test: prepare for asynchronously closed sstables_manager
test: sstable_datafile_test: prepare for asynchronously closed sstables_manager
test: sstable_conforms_to_mutation_source_test: remove references to test_sstables_manager
test: sstable_3_x_test: remove test_sstables_manager references
test: schema_changes_test: drop use of test_sstables_manager
mutation_test: adjust for column_family_test_config accepting an sstables_manager
test: lib: sstable_utils: stop using test_sstables_manager
test: sstables test_env: introduce manager() accessor
test: sstables test_env: introduce do_with_async_sharded()
test: sstables test_env: introduce do_with_async_returning()
test: lib: sstable test_env: prepare for life as a sharded<> service
test: schema_changes_test: properly close sstables::test_env
test: sstable_mutation_test: avoid constructing temporary sstables::test_env
test: mutation_reader_test: avoid constructing temporary sstables::test_env
test: sstable_3_x_test: avoid constructing temporary sstables::test_env
test: lib: test_services: pass sstables_manager to column_family_test_config
test: lib: sstables test_env: implement tests_env::manager()
test: sstable_test: detemplate write_and_validate_sst()
test: sstable_test_env: detemplate do_with_async()
test: sstable_datafile_test: drop bad 'return'
table: clear sstable set when stopping
table: prevent table::stop() race with table::query()
database: close sstable_manager:s
sstables_manager: introduce a stub close()
sstable_directory_test: fix threading confusion in make_sstable_directory_for*() functions
test: sstable_datafile_test: reorder table stop in compaction_manager_test
test: view_build_test: test_view_update_generator_register_semaphore_unit_leak: do not discard future in timer
test: view_build_test: fix threading in test_view_update_generator_register_semaphore_unit_leak
view: view_update_generator: drop references to sstables when stopping
test_view_update_generator_register_semaphore_unit_leak creates a continuation chain
inside a timer, but does not wait for it. This can result in part of the chain
being executed after its captures have been destroyed.
This is unlikely to happen since the timer fires only if the test fails, and
tests never fail (at least in the way that one expects).
Fix by waiting for that future to complete before exiting the thread.
test_view_update_generator_register_semaphore_unit_leak uses a thread function
in do_with_cql_env(), even though the latter doesn't promise a thread and
accepts a regular function-returning-a-future. It happens to work because the
function happens to be called in a thread, but this isn't guaranteed.
Switch to do_with_cql_env, which guarantees a thread context.
In preparations of non-inactive read stats being added to the semaphore,
rename its existing stats struct and member to a more generic name.
Fields, whose name only made sense in the context of the old name are
adjusted accordingly.
fea83f6 introduced a race between processing (and hence removing)
sstables from `_sstables_with_tables` and registering new ones. This
manifested in sstables that were added concurrently with processing a
batch for the same sstables being dropped and the semaphore units
associated with them not returned. This resulted in repairs being
blocked indefinitely as the units of the semaphore were effectively
leaked.
This patch fixes this by moving the contents of `_sstables_with_tables`
to a local variable before starting the processing. A unit test
reproducing the problem is also added.
Fixes: #6892
Tests: unit(dev)
Signed-off-by: Botond Dénes <bdenes@scylladb.com>
Message-Id: <20200817160913.2296444-1-bdenes@scylladb.com>
"
While working on another patch I was getting odd compiler errors
saying that a call to ::make_shared was ambiguous. The reason was that
seastar has both:
template <typename T, typename... A>
shared_ptr<T> make_shared(A&&... a);
template <typename T>
shared_ptr<T> make_shared(T&& a);
The second variant doesn't exist in std::make_shared.
This series drops the dependency in scylla, so that a future change
can make seastar::make_shared a bit more like std::make_shared.
"
* 'espindola/make_shared' of https://github.com/espindola/scylla:
Everywhere: Explicitly instantiate make_lw_shared
Everywhere: Add a make_shared_schema helper
Everywhere: Explicitly instantiate make_shared
cql3: Add a create_multi_column_relation helper
main: Return a shared_ptr from defer_verbose_shutdown
"
Non-paged queries completely ignore the query result size limiter
mechanism. They consume all the memory they want. With sufficiently
large datasets this can easily lead to a handful or even a single
unpaged query producing an OOM.
This series continues the work started by 134d5a5f7, by introducing a
configurable pair of soft/hard limit (default to 1MB/100MB) that is
applied to otherwise unlimited queries, like reverse and unpaged ones.
When an unlimited query reaches the soft limit a warning is logged. This
should give users some heads-up to adjust their application. When the
hard limit is reached the query is aborted. The idea is to not greet
users with failing queries after an upgrade while at the same time
protect the database from the really bad queries. The hard limit should
be decreased from time to time gradually approaching the desired goal of
1MB.
We don't want to limit internal queries, we trust ourselves to either
use another form of memory usage control, or read only small datasets.
So the limit is selected according to the query class. User reads use
the `max_memory_for_unlimited_query_{soft,hard}_limit` configuration
items, while internal reads are not limited. The limit is obtained by
the coordinator, who passes it down to replicas using the existing
`max_result_size` parameter (which is not a special type containing the
two limits), which is now passed on every verb, instead of once per
connection. This ensures that all replicas work with the same limits.
For normal paged queries `max_result_size` is set to the usual
`query::result_memory_limiter::maximum_result_size` For queries that can
consume unlimited amount of memory -- unpaged and reverse queries --
this is set to the value of the aforementioned
`max_memory_for_unlimited_query_{soft,hard}_limit` configuration item,
but only for user reads, internal reads are not limited.
This has the side-effect that reverse reads now send entire
partitions in a single page, but this is not that bad. The data was
already read, and its size was below the limit, the replica might as well
send it all.
Fixes: #5870
"
* 'nonpaged-query-limit/v5' of https://github.com/denesb/scylla: (26 commits)
test: database_test: add test for enforced max result limit
mutation_partition: abort read when hard limit is exceeded for non-paged reads
query-result.hh: move the definition of short_read to the top
test: cql_test_env: set the max_memory_unlimited_query_{soft,hard}_limit
test: set the allow_short_read slice option for paged queries
partition_slice_builder: add with_option()
result_memory_accounter: remove default constructor
query_*(): use the coordinator specified memory limit for unlimited queries
storage_proxy: use read_command::max_result_size to pass max result size around
query: result_memory_limiter: use the new max_result_size type
query: read_command: add max_result_size
query: read_command: use tagged ints for limit ctor params
query: read_command: add separate convenience constructor
service: query_pager: set the allow_short_read flag
result_memory_accounter: check(): use _maximum_result_size instead of hardcoded limit
storage_proxy: add get_max_result_size()
result_memory_limiter: add unlimited_result_size constant
database: add get_statement_scheduling_group()
database: query_mutations(): obtain the memory accounter inside
query: query_class_config: use max_result_size for the max_memory_for_unlimited_query field
...
It is important that all replicas participating in a read use the same
memory limits to avoid artificial differences due to different amount of
results. The coordinator now passes down its own memory limit for reads,
in the form of max_result_size (or max_size). For unpaged or reverse
queries this has to be used now instead of the locally set
max_memory_unlimited_query configuration item.
To avoid the replicas accidentally using the local limit contained in
the `query_class_config` returned from
`database::make_query_class_config()`, we refactor the latter into
`database::get_reader_concurrency_semaphore()`. Most of its callers were
only interested in the semaphore only anyway and those that were
interested in the limit as well should get it from the coordinator
instead, so this refactoring is a win-win.
Currently, encountering an error when loading view build progress
would result in view builder refusing to start - which also means
that future views would not be built until the server restarts.
A more user-friendly solution would be to log an error message,
but continue to boot the view builder as if no views are currently
in progress, which would at least allow future views to be built
correctly.
The test case is also amended, since now it expects the call
to return that "no view builds are in progress" instead of
an exception.
Fixes#6934
Tests: unit(dev)
Message-Id: <9f26de941d10e6654883a919fd43426066cee89c.1595922374.git.sarna@scylladb.com>
This replaces a lot of make_lw_shared(schema(...)) with
make_shared_schema(...).
This makes it easier to drop a dependency on the differences between
seastar::make_shared and std::make_shared.
Signed-off-by: Rafael Ávila de Espíndola <espindola@scylladb.com>
A test case which reproduces the view update generator hang, where the
staging reader consumes all resources and leaves none for the pre-image
reader which blocks on the semaphore indefinitely.
The schema_tables.hh -> migration_manager.hh couple seems to work as one
of "single header for everyhing" creating big blot for many seemingly
unrelated .hh's.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
Streaming is handled by just once group for CPU scheduling, so
separating it into read and write classes for I/O is artificial, and
inflates the resources we allow for streaming if both reads and writes
happen at the same time.
Merge both classes into one class ("streaming") and adjust callers. The
merged class has 200 shares, so it reduces streaming bandwidth if both
directions are active at the same time (which is rare; I think it only
happens in view building).
This test doesn't work with higher smp counts, because it relies on
dealing with keys named 'a' and 'b' and creates SSTables containing one
of them manually. This throws an exception if we happen to execute on
a shard that don't own the tokens corresponding to those keys.
This patch avoids that problem by pre-selecting keys that we know to
belong to the current shard in which the test is executed.
Signed-off-by: Glauber Costa <glauber@scylladb.com>
