Pursuing your vision is difficult. Especially, if this vision is a multi-threaded in-memory database. A couple of days ago I've got a working implementation of 3-thread layout for Tarantool core. Mm... what's that supposed to mean if Tarantool is single-threaded? First, it's not. The binary log is written in a separate thread. Checkpointing (snapshotting) is done in a separate thread. Replication relays run in their own threads. But the transaction processor still runs in 1 thread only. You're supposed to shard anyway, so why not begin with shardingon a single multi-core server, that's the idea. One thing, however, which was part of transaction processor thread but didn't belong to it was the client/server protocol, handling the socket I/O. So, now we have 3 major threads: the network thread, the transaction processor thread, and the binlog thread. Once in a while there is a checkpoint thread that gets involved. The benchmark numbers were supposed to go up. But not only that, they were supposed to go up while still maintaining at least comparable CPU utilization. I wasn't interested in 20% performance boost for 100% incraese in CPU usage, even though that's exactly what I got at first. So, finally, after a day of tuning and patching, and cooling off the hot mutexes I got my numbers. +25% performance increase for +30% higher CPU utilization. It's +25% only because in this specific benchmark network I/O is only 25% of the original performance profile, the rest is B-trees operations and transaction management, stuff that stayed in the transaction thread. Happily, I pushed the patch to the next-release tree. And yesterday we ran first YCSB benchmarks with it. Now, YCSB is a stupid idea for a benchmark. For example, YCSB RO benchmark is N clients (for example, N is 16) issuing tiny requests in synchronous fashion. Essentially, with few clients it means the client and the server operate in lock-step fashion - the cliens fire up a bunch of requests over network, and wait for esults. The server kicks in, handles the input, and responds. 30% user time, 70% sys time during the benchmark. Now, in this particular test Tarantool results got worse, while CPU usage went significantly up. On top of a lot of kernelspace and userspace switching, the patch added a bunch of network/transaction thread switching. The same lock step, one step further. And now I have to think what to do with it. We can't look silly even on a silly benchmark. Multi-threading, evidently, needs more work.