We keep track of all updates and store the minimal values of timestamps,
TTLs and local deletion times across all the inserted data.
These values are written as a part of serialization_header for
Statistics.db and used for delta-encoding values when writing Data.db
file in SSTables 3.0 (mc) format.
For #1969.
Signed-off-by: Vladimir Krivopalov <vladimir@scylladb.com>
Previously it was also possible to pass a frozen_mutation to it.
Now we de-serialize frozen mutations at the calling side.
This is a pre-requisite for collecting memtable statistics needed for
writing into the SSTables 3.0 format.
For #1969.
Signed-off-by: Vladimir Krivopalov <vladimir@scylladb.com>
buffer_size() exposes the collective size of the external memory
consumed by the mutattion-fragments in the flat reader's buffer. This
provides a basis to build basic memory accounting on. Altought this is
not the entire memory consumption of any given reader it is the most
volatile component and usually by far the largest one too.
In this patchset I am resubmitting Avi's enablement of the CPU scheduler
in his behalf. I've done a ton of testing in the series and there are
some improvements / changes that I had previously sent as a separate series.
What you see here is the result of merging that work.
After this patchset is applied, workloads are smoother and we are able to
uphold the pre-defined shares among the various actors.
We also finally have everything we need to merge the CPU and I/O controllers.
After that is done the code is now much simpler. But also, as a bonus,
controllers that were previously available for I/O only (compactions) are
enabled for CPU as well.
* git@github.com:glommer/scylla.git cpusched-v7:
Avi Kivity (4):
database, sstables, compaction: convert use of thread_scheduling_group
to seastar cpu scheduler
memtable, database: make memtable::clear_gently() inherit
scheduling_group
config: mark background_writer_scheduling_quota as Unused
database: place data_query execution stage into scheduling_group
Glauber Costa (9):
database, main: set up scheduling_groups for our main tasks
row_cache: actually use the scheduling group for update_cache
allow update_cache and clear_gently to use the entire task quota.
database: remove cpu_flush_quota metric
controllers: retire auto_adjust_flush_quota
controllers: allow memtable I/O controller to have shares statically
set
controllers: update control points for memtable I/O controller
controllers: allow a static priority to override the controller output
controllers: unify the I/O and CPU controllers
We have had a quota of partitions to process in clear_gently /
update_cache, so that we don't overwork. However, with those things now
being in their own task group there is no harm in allowing it to run
until we reach a natural preemption point.
While we are at it, clear_gently did not check for need_preempt()
before, so this patch fixes it.
Signed-off-by: Glauber Costa <glauber@scylladb.com>
When digest is requested, pre-calculate the cell's hash. A downside of
this approach is that more work will be done when there are multiple
versions of a row that contain values for the same cell, but we expect
these cases to be rare and the upside of caching a cell's hash to
compensate for the extra work.
Signed-off-by: Duarte Nunes <duarte@scylladb.com>
Retryable code that has side effects is a recipe for bugs. This patch
reworkds the snapshot reader so that the amount of logic run with
reclamation disabled is minimal and has a very limited side effects.
In the last patch, we enabled per-request timeouts, we enable timeouts
in fill_buffer. There are many places, though, in which we
fast_forward_to before we fill_buffer, so in order to make that
effective we need to propagate the timeouts to fast_forward_to as well.
In the same way as fill_buffer, we make the argument optional wherever
possible in the high level callers, making them mandatory in the
implementations.
Signed-off-by: Glauber Costa <glauber@scylladb.com>
As part of the work to enable per-request timeouts, we enable timeouts
in fill_buffer.
The argument is made optional at the main classes, but mandatory in all
the ::impl versions. This way we'll make sure we didn't forget anything.
At this point we're still mostly passing that information around and
don't have any entity that will act on those timeouts. In the next patch
we will wire that up.
Signed-off-by: Glauber Costa <glauber@scylladb.com>
The wrapper is no longer needed because
read_range_rows returns ::mutation_reader instead of
sstables::mutation_reader and the reader returned from
it keeps the pointer to shared_sstable that was used to
create the reader.
Signed-off-by: Piotr Jastrzebski <piotr@scylladb.com>
Since we started accounting virtual dirty memory we no longer have a cap
on real dirty memory. In most situations that is not needed, since real
dirty will just be at most twice as much as virtual dirty (current
flushing memtable plus new memtable).
However, due to things like cache updates and component flushing we can
end up having a lot of memtables that are virtually freed but not yet
fully released, leading real dirty memory to explode using all the box'
memory.
This patch adds a cap on real dirty memory as well. Because of the
hierarchical nature of region_group, if the parent blocks due to memory
depletion, so will the child (virtual dirty region group).
After that is done, we need to make sure that dirty memory is not seen
as freed until the cache update is done. Until a particular partition is
moved to the cache it is not evictable. As a result we can OOM the
system if we have a lot of pending cache updates as the writes will not
be throttled and memory won't be made available.
This patch pins the memory used by the region as real dirty before the
cache update starts, and unpins it when it is over. In the mean time it
gradually releases memory of the partitions that are being moved to
cache.
I have verified in a couple of workloads that the amount of memory
accounted through this is the same amount of memory accounted through
the memtable flush procedure.
Fixes#1942
* git@github.com:glommer/scylla.git glommer/update-cache-v4:
row_cache: modernize use of seastar threads
mutation_partition: estimate size of partition
memtable: factor out calculation of memtable_entry memory size
memtable: add a method to export memtable's dirty memory manager
dirty_memory_manager: block if we hit the real dirty limit
dirty_memory_manager: add functions to manipulate real dirty
partition: add method to calculate memory size of a partition
row cache: pin real dirty during cache updates.
The total size is the sum of two components. Add a method that
does that sum so this code gets easier to reuse.
Signed-off-by: Glauber Costa <glauber@scylladb.com>
Rename flat_mutation_reader_from_mutation to
flat_mutation_reader_from_mutations.
Make it work with std::vector<mutation> instead of a single
mutation.
Signed-off-by: Piotr Jastrzebski <piotr@scylladb.com>
This method creates a flat_mutation_reader
instead of mutation_reader. All users will be gradually
converted to the new interface. make_reader is implemented
using make_flat_reader and will be removed once all users
are migrated.
Signed-off-by: Piotr Jastrzebski <piotr@scylladb.com>
query::full_slice doesn't select any regular or static columns, which
is at odds with the expectations of its users. This patch replaces it
with the schema::full_slice() version.
Refs #2885
Signed-off-by: Duarte Nunes <duarte@scylladb.com>
Message-Id: <1507732800-9448-2-git-send-email-duarte@scylladb.com>
"This changeset is the first step to flatten mutation_reader.
Then it introduces new mutation_fragment types for partition header and end of partition.
Using those a new flat_mutation_reader is defined.
Finally it introduces converters between new flat_mutation_reader and
old mutation_reader."
* 'haaawk/flattened_mutation_reader_v12' of github.com:scylladb/seastar-dev:
Add tests for flat_mutation_reader
Introduce conversion from flat_mutation_reader to mutation_reader
Introduce conversion from mutation_reader to flat_mutation_reader
Introduce flat_mutation_reader
Extract FlattenedConsumer concept using GCC6_CONCEPT
Introduce partition_end mutation_fragment
Introduce a position for end of partition
Introduce partition_start mutation_fragment
Introduce FragmentConsumer
Introduce a position for partition start
streamed_mutation: Extract concepts using GCC6_CONCEPT macro
This type of mutation_fragment will be used in new mutation_reader
to signal the end of the current partition.
Signed-off-by: Piotr Jastrzebski <piotr@scylladb.com>
This type of mutation_fragment will be used in new mutation_reader
to signal the beginning of the next partition.
Signed-off-by: Piotr Jastrzebski <piotr@scylladb.com>
This patch refactors how the flush permit lifetime is managed,
dropping the current hash table in favour of a RAII approach.
Signed-off-by: Duarte Nunes <duarte@scylladb.com>
This patch refactors how the flush permit lifetime is managed,
dropping the current hash table in favour of a RAII approach.
Signed-off-by: Duarte Nunes <duarte@scylladb.com>
In commit c63e88d556, support was added for
fast_forward_to() in data_consume_rows(). Because an input stream's end
cannot be changed after creation, that patch ignores the specified end
byte, and uses the end of file as the end position of the stream.
As result of this, even when we want to read a specific byte range (e.g.,
in the repair code to checksum the partitions in a given range), the code
reads an entire 128K buffer around the end byte, or significantly more, with
read-ahead enabled. This causes repair to do more than 10 times the amount
of I/O it really has to do in the checksumming phase (which in the current
implementation, reads small ranges of partitions at a time).
This patch has two levels:
1. In the lower level, sstable::data_consume_rows(), which reads all
partitions in a given disk byte range, now gets another byte position,
"last_end". That can be the range's end, the end of the file, or anything
in between the two. It opens the disk stream until last_end, which means
1. we will never read-ahead beyond last_end, and 2. fast_fordward_to() is
not allowed beyond last_end.
2. In the upper level, we add to the various layers of sstable readers,
mutation readers, etc., a boolean flag mutation_reader::forwarding, which
says whether fast_forward_to() is allowed on the stream of mutations to
move the stream to a different partition range.
Note that this flag is separate from the existing boolean flag
streamed_mutation::fowarding - that one talks about skipping inside a
single partition, while the flag we are adding is about switching the
partition range being read. Most of the functions that previously
accepted streamed_mutation::forwarding now accept *also* the option
mutation_reader::forwarding. The exception are functions which are known
to read only a single partition, and not support fast_forward_to() a
different partition range.
We note that if mutation_reader::forwarding::no is requested, and
fast_forward_to() is forbidden, there is no point in reading anything
beyond the range's end, so data_consume_rows() is called with last_end as
the range's end. But if forwarding::yes is requested, we use the end of the
file as last_end, exactly like the code before this patch did.
Importantly, we note that the repair's partition reading code,
column_family::make_streaming_reader, uses mutation_reader::forwarding::no,
while the other existing reading code will use the default forwarding::yes.
In the future, we can further optimize the amount of bytes read from disk
by replacing forwarding::yes by an actual last partition that may ever be
read, and use its byte position as the last_end passed to data_consume_rows.
But we don't do this yet, and it's not a regression from the existing code,
which also opened the file input stream until the end of the file, and not
until the end of the range query. Moreover, such an improvement will not
improve of anything if the overall range is always very large, in which
case not over-reading at its end will not improve performance.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20170619152629.11703-1-nyh@scylladb.com>
This reverts commit 317d7fc253 (and also the
related 2c57ab84b2). It causes crashes
during range scans, reported by Gleb:
"To reproduce I run SELECT * FROM keyspace1.standard1; on typical c-s
dataset and 3 node cluster.
Backtrace:
at /home/gleb/work/seastar/seastar/core/apply.hh:36
rvalue=<unknown type in /home/gleb/work/seastar/build/release/scylla, CU 0x54cf307, DIE 0x55ebf2a>) at /home/gleb/work/seastar/seastar/core/do_with.hh:57
range=std::vector of length 6, capacity 8 = {...}) at /home/gleb/work/seastar/seastar/core/future-util.hh:142
at ./seastar/core/future.hh:890
at /home/gleb/work/seastar/seastar/core/future-util.hh:119
at /home/gleb/work/seastar/seastar/core/future-util.hh:142
In commit c63e88d556, support was added for
fast_forward_to() in data_consume_rows(). Because an input stream's end
cannot be changed after creation, that patch ignores the specified end
byte, and uses the end of file as the end position of the stream.
As result of this, even when we want to read a specific byte range (e.g.,
in the repair code to checksum the partitions in a given range), the code
reads an entire 128K buffer around the end byte, or significantly more, with
read-ahead enabled. This causes repair to do more than 10 times the amount
of I/O it really has to do in the checksumming phase (which in the current
implementation, reads small ranges of partitions at a time).
This patch has two levels:
1. In the lower level, sstable::data_consume_rows(), which reads all
partitions in a given disk byte range, now gets another byte position,
"last_end". That can be the range's end, the end of the file, or anything
in between the two. It opens the disk stream until last_end, which means
1. we will never read-ahead beyond last_end, and 2. fast_fordward_to() is
not allowed beyond last_end.
2. In the upper level, we add to the various layers of sstable readers,
mutation readers, etc., a boolean flag mutation_reader::forwarding, which
says whether fast_forward_to() is allowed on the stream of mutations to
move the stream to a different partition range.
Note that this flag is separate from the existing boolean flag
streamed_mutation::fowarding - that one talks about skipping inside a
single partition, while the flag we are adding is about switching the
partition range being read. Most of the functions that previously
accepted streamed_mutation::forwarding now accept *also* the option
mutation_reader::forwarding. The exception are functions which are known
to read only a single partition, and not support fast_forward_to() a
different partition range.
We note that if mutation_reader::forwarding::no is requested, and
fast_forward_to() is forbidden, there is no point in reading anything
beyond the range's end, so data_consume_rows() is called with last_end as
the range's end. But if forwarding::yes is requested, we use the end of the
file as last_end, exactly like the code before this patch did.
Importantly, we note that the repair's partition reading code,
column_family::make_streaming_reader, uses mutation_reader::forwarding::no,
while the other existing reading code will use the default forwarding::yes.
In the future, we can further optimize the amount of bytes read from disk
by replacing forwarding::yes by an actual last partition that may ever be
read, and use its byte position as the last_end passed to data_consume_rows.
But we don't do this yet, and it's not a regression from the existing code,
which also opened the file input stream until the end of the file, and not
until the end of the range query. Moreover, such an improvement will not
improve of anything if the overall range is always very large, in which
case not over-reading at its end will not improve performance.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20170614072122.13473-1-nyh@scylladb.com>
Use per CF-id reference count instead, and use handles as result of
add operations. These must either be explicitly released or stored
(rp_set), or they will release the corresponding replay_position
upon destruction.
Note: this does _not_ remove the replay positioning ordering requirement
for mutations. It just removes it as a means to track segment liveness.
We can make the dependency more abstract by using mutation_source
instead of an sstable.
Will be useful in some stress tests which want to avoid the disk, but
is also good for the sake of decoupling.
Message-Id: <1495729508-30081-2-git-send-email-tgrabiec@scylladb.com>
