Recently I used YCSB to do some database benchmarking. I tried to change some default options, when I changed write_buffer_size to 2M, the database always made an error when construct Memtable.
Execute the constructor of Memtable correctly.
Error:/rocksdb/db/memtable.cc:117: rocksdb::MemTable::MemTable(const rocksdb::InternalKeyComparator&, const rocksdb::ImmutableOptions&, const rocksdb::MutableCFOptions&, rocksdb::WriteBufferManager*, rocksdb::SequenceNumber, uint32_t): Assertion `!ShouldScheduleFlush()’ failed.
When a Memtable is constructed, the state of flush_state_ will be checked first, which cannot be FLUSH_REQUESTED.
However, in the previous UpdateFlushState(), since ShouldFlushNow() returned true, flush_state_ was set to FLUSH_REQUESTED, which caused it to fail in the asset below.
I read the source code of ShouleFlushNow() carefully, when I debug to this function, the kArenaBlockSize is 16M and the write_buffer_size is 2M. ShouldFlushNow() will not return through the following two logics.
Instead return the result with this line of code at the end. I noticed the comment, which states that this means Arena has already allocated his “last block”. At this time, my arena_.AllocatedAndUnused() is 1384, which is much smaller than 0.25*kArenaBlockSize.
Steps to reproduce the behavior
Simply, just set write_buffer_size to 2M or less, or a slightly larger number.(: