Profiling alternator implied that JSON parsing takes up a fair amount
of CPU, and as such should be optimized. libjsoncpp is a standard
library for handling JSON objects, but it also proves slower than
rapidjson, which is hereby used instead.
The results indicated that libjsoncpp used roughly 30% of CPU
for a single-shard alternator instance under stress, while rapidjson
dropped that usage to 18% without optimizations.
Future optimizations should include eliding object copying, string copying
and perhaps experimenting with different JSON allocators.
The CQL type singletons like utf8_type et al. are separate for separate
shards and cannot be used across shards. So whatever hash tables we use
to find them, also needs to be per-shard. If we fail to do this, we
get errors running the debug build with multiple shards.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20190804165904.14204-1-nyh@scylladb.com>
Attributes used to be written into the database in raw JSON format,
which is far from optimal. This patch introduces more robust
serializationi routines for simple alternator types: S, B, BOOL, N.
Serialization uses the first byte to encode attribute type
and follows with serializing data in binary form.
More complex types (sets, lists, etc.) are currently still
serialized in raw JSON and will be optimized in follow-up patches.
Message-Id: <10955606455bbe9165affb8ac8fba4d9e7c3705f.1559646761.git.sarna@scylladb.com>
