This limits the disk IO for writing TSM files during compactions
and snapshots. This helps reduce the spiky IO patterns on SSDs and
when compactions run very quickly.
* Introduces EXPLAIN ANALYZE command, which
produces a detailed tree of operations used to
execute the query.
introduce context.Context to APIs
metrics package
* create groups of named measurements
* safe for concurrent access
tracing package
EXPLAIN ANALYZE implementation for OSS
Serialize EXPLAIN ANALYZE traces from remote nodes
use context.Background for tests
group with other stdlib packages
additional documentation and remove unused API
use influxdb/pkg/testing/assert
remove testify reference
This changes the compaction scheduling to better utilize the available
cores that are free. Previously, a level was planned in its own goroutine
and would kick off a number of compactions groups. The problem with this
model was that if there were 4 groups, and 3 completed quickly, the planning
would be blocked for that level until the last group finished. If the compactions
at the prior level are running more quickly, a large backlog could accumlate.
This now moves the planning to a single goroutine that plans each level in
succession and starts as many groups as it can. When one group finishes,
the planning will start the next group for the level.
This commit replaces the previous hashing algorithm used by the pkg.Filter with
one based on xxhash. Further, taking from the hashing literature, we can
represent k hashes with only two hash function, where previously Filter was using
four.
Further, unlike `murmur3`, `xxhash` is allocation-free, so allocations have
dramatically reduced when inserting and checking for hashes.
The new algorithm uses only one formula and needs no additional bias corrections for the entire range of cardinalities,
therefore, it is more efficient and simpler to implement. Our simulations show that the accuracy provided by the new
algorithm is as good as or better than the accuracy provided by either of HyperLogLog or HyperLogLog++. The sparse
representation was kept in to provide better low cardinality accuracy. However the linear counting and range estimations
are replaced.
This pool was previously a pool.Bytes to avoid repetitive allocations.
It was recently switchted to a sync.Pool because pool.Bytes held onto
very larger buffers at times which were never released. sync.Pool is
showing up in allocation profiles quite frequently.
This switches the pool to a new pool that limits how many buffers are
in the pool as well as the max size of each buffer in the pool. This
provides better bounds on allocations.
Stuart Carnie
Ben Johnson
Edd Robinson
Jason Wilder
Matt McCoy
Seif Lotfy