Sergei Petrunia added a comment - 2017-08-14 11:16 This is not easily reproducible. I noticed there is a typo in the error log: 2017-08-14 10:57:07 140082647533376 [ERROR] RocksDB: Can't enable both use_direct_io_for_flush_and_compaction use_direct_io_for_flush_and_compaction and allow_mmap_writes but it cant' cause this issue, can it...

Sergei Petrunia added a comment - 2017-08-14 17:57 The issue comes from these lines in use_direct_reads_writes.test --exec echo "restart:--rocksdb_use_direct_io_for_flush_and_compaction=1 --rocksdb_allow_mmap_writes=1" >$_expect_file_name --sleep 0.1 --exec echo "restart:" >$_expect_file_name MTR's check_expected_crash_and_restart function is invoked whenever mysqld process crashes or exits. if mysqld.expect file is not present, then this is considered to be a test failure if mysqld.expect file is present, it has commands to either wait or restart the server * in either case, .expect file is deleted after MTR has read the command from it. In order to start the server with invalid arguments, use_direct_reads_writes.test puts them into .expect file and then it MUST be able to provide another .expect file. This must happen after MTR has read and deleted the first file before the server has exited and MTR started to look what to do about this. sleep 0.1 achieves this most of the time but this is still a race condition.