Seems that miner.rocks that supported the longer part of blockchain is shut down now.
Daemon become unusable, 100% cpu usage with 90% iowait, full log of
2018-02-28 10:01:29.285 [P2P2] INFO stacktrace src/common/stack_trace.cpp:120 Exception: cryptonote::BLOCK_DNE
But after resync from 12h snapshot it worked ok and pool was back online in a few minutes.