column_family
This patch adds a getter for the dirty_memory_region_group in the
database object and add an occupency method to column family that
returns the total occupency in all the memtable in the column family.
Signed-off-by: Amnon Heiman <amnon@cloudius-systems.com>
All database code was converted to is when storage_proxy was made
distributed, but then new code was written to use storage_proxy& again.
Passing distributed<> object is safer since it can be passed between
shards safely. There was a patch to fix one such case yesterday, I found
one more while converting.
Unlike cache, dirty memory cannot be evicted at will, so we must limit it.
This patch establishes a hard limit of 50% of all memory. Above that,
new requests are not allowed to start. This allows the system some time
to clean up memory.
Note that we will need more fine-grained bandwidth control than this;
the hard limit is the last line of defense against running our of reclaimable
memory.
Tested with a mixed read/write load; after reads start to dominate writes
(due to the proliferation of small sstables, and the inability of compaction
to keep up, dirty memory usage starts to climb until the hard stop prevents
it from climbing further and ooming the server).
"Initial implementation/transposition of commit log replay.
* Changes replay position to be shard aware
* Commit log segment ID:s now follow basically the same scheme as origin;
max(previous ID, wall clock time in ms) + shard info (for us)
* SStables now use the DB definition of replay_position.
* Stores and propagates (compaction) flush replay positions in sstables
* If CL segments are left over from a previous run, they, and existing
sstables are inspected for high water mark, and then replayed from
those marks to amend mutations potentially lost in a crash
* Note that CPU count change is "handled" in so much that shard matching is
per _previous_ runs shards, not current.
Known limitations:
* Mutations deserialized from old CL segments are _not_ fully validated
against existing schemas.
* System::truncated_at (not currently used) does not handle sharding afaik,
so watermark ID:s coming from there are dubious.
* Mutations that fail to apply (invalid, broken) are not placed in blob files
like origin. Partly because I am lazy, but also partly because our serial
format differs, and we currently have no tools to do anything useful with it
* No replay filtering (Origin allows a system property to designate a filter
file, detailing which keyspace/cf:s to replay). Partly because we have no
system properties.
There is no unit test for the commit log replayer (yet).
Because I could not really come up with a good one given the test
infrastructure that exists (tricky to kill stuff just "right").
The functionality is verified by manual testing, i.e. running scylla,
building up data (cassandra-stress), kill -9 + restart.
This of course does not really fully validate whether the resulting DB is
100% valid compared to the one at k-9, but at least it verified that replay
took place, and mutations where applied.
(Note that origin also lacks validity testing)"
This patch adds the get_non_system_keyspaces that found in origin and
expose the replication strategy. With the get_replication_strategy
method.
Signed-off-by: Amnon Heiman <amnon@cloudius-systems.com>
Adding to API function to return count of sstables in L0 if leveled
compaction strategy is enabled, 0 otherwise. Currently, we don't
support leveled compaction strategy, so function to return count of
sstables in L0 always return zero.
Signed-off-by: Raphael S. Carvalho <raphaelsc@cloudius-systems.com>
It was noticed that the same sstable files could be selected for
compaction if concurrent compaction happens on the same cf.
That's possible because compaction manager uses 2 tasks for
handling compactions.
Solution is to not duplicate cf in the compaction manager queue,
and re-schedule compaction for a cf if needed.
Signed-off-by: Raphael S. Carvalho <raphaelsc@cloudius-systems.com>
"This series expose statistics from the row_cache in the cache_service API.
After this series the following methods will be available:
get_row_hits
get_row_requests
get_row_hit_rate
get_row_size
get_row_entries"
We need a way to remove a column family from the compaction manager
because when dropping a column family we need to make sure that the
compaction manager doesn't hold a reference to it anymore.
So compaction manager queue is now of column_family, allowing us
to cancel requests pertaining to a column family being dropped.
There may be an ongoing compaction for the column family being
dropped, so we also need to wait for its termination.
Testcase for compaction manager was also adapted and improved.
Signed-off-by: Raphael S. Carvalho <raphaelsc@cloudius-systems.com>
This expose the row_cache in the column family, it will be used by the
API to get the row_cache statistic information.
Signed-off-by: Amnon Heiman <amnon@cloudius-systems.com>
"Histograms are used to collect latency information, in Origin, many of the
operations are timed, this is a potential performance issue. This series adds
an option to sample the operations, where small amount will be timed and the
most will only be counted.
This will give an estimation for the statistics, while keeping an accurate
count of the total events and have neglectible performance impact.
The first to use the modified histogram are the column family for their read
and write."
Conflicts:
database.hh
We can catch most errors when we try to load an sstable. But if the TOC file is
the one missing, we won't try to load the sstable at all. This case is still an
invalid case, but it is way easier for us to treat it by waiting for all files
to be loaded, and then checking if we saw a file during scan_dir, without its
corresponding TOC.
Fixes#114
Signed-off-by: Glauber Costa <glommer@cloudius-systems.com>
Currently, each column family creates a fiber to handle compaction requests
in parallel to the system. If there are N column families, N compactions
could be running in parallel, which is definitely horrible.
To solve that problem, a per-database compaction manager is introduced here.
Compaction manager is a feature used to service compaction requests from N
column families. Parallelism is made available by creating more than one
fiber to service the requests. That being said, N compaction requests will
be served by M fibers.
A compaction request being submitted will go to a job queue shared between
all fibers, and the fiber with the lowest amount of pending jobs will be
signalled.
Signed-off-by: Raphael S. Carvalho <raphaelsc@cloudius-systems.com>
With the use of sparse histogram, the read and write counters in the
column_family stats can be used.
The total impact on performanc should be neglectible.
Signed-off-by: Amnon Heiman <amnon@cloudius-systems.com>
ASan does not like commit 05c23c7f73
("database: Add create_keyspace_on_all() helper"):
==8112==WARNING: AddressSanitizer failed to allocate 0x7f88b84fc690 bytes
==8112==AddressSanitizer's allocator is terminating the process instead of returning 0
==8112==If you don't like this behavior set allocator_may_return_null=1
==8112==Sanitizer CHECK failed: ../../../../libsanitizer/sanitizer_common/sanitizer_allocator.cc:147 ((0)) != (0) (0, 0)
I was not able to determine the source of the bug. Make ASan happy by
reverting the code movement and using the "cpu zero" trick we use for
table creation.
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
Add a create_keyspace_on_all() helper which is needed for sending just
one event notification per created keyspace, not one per shard.
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
"This series improves parallel CQL table creation to validate CF UUID.
This should bring us closer to Origin behavior when there's multiple
cassandra-stress processes started at the same time."
This adds the stats object to column_family.
It set the write counter in the write path and support the pending_flush
counter.
The stats object contains information for switch_count, number of
pending flushes, and counters for read, write, and range.
Signed-off-by: Amnon Heiman <amnon@cloudius-systems.com>
Abillity to enable/disable specific sub-modules - this settings do not
affect system tables which are allways persisted,cached and written to
commitlog
enable-in-memory-data-store marks if tables will be written/read to/from
disk
enable-commitllog marks if tables will be written to commitlog
enable-cache marks if tables will be written/read to/from cache
Please note in-memory-data-store does not change the read path so "old"
sstables are still read and cache may be used to cache their data
Signed-off-by: Shlomi Livne <shlomi@cloudius-systems.com>
