Csv import meet error "There are too many timeseries in memory"

[LangYuanzh]

Meet this error when import data to iotdb(version: 1.0.0):
"Meet error when insert csv because 507: There are too many timeseries in memory, please increase MAX_HEAP_SIZE in datanode-env.sh/bat, restart and create timeseries again."

Are there any other options or configurations to avoid this as for now i can`t increase memory size of the server? I don't understand why there are so many timeseries in memory, as there are no queries at the moment. If these timeseries in memory are cache of imported data, when will the memory will be released?