[BUG] Issues when multithreading with simstring

[youngbinkim0]

Bug Description
I saw that QuickUMLS supports multithreading through the use of unqlite rather than leveldb. However, I noticed that terms are not being returned on the second instance if I run two instances of QuickUMLS referring to the same database. The issue seems to be coming from SimstringDBReader as seen in the example below. How can I ensure that multiple SimstringDBReaders can read the same database? I want to multithread QuickUMLS without having to copy the database multiple times.
 
To Reproduce

import quickumls
simstring_reader = quickumls.toolbox.SimstringDBReader(path="your_path_here/umls-simstring.db", similarity_name="jaccard", threshold=0.9)
simstring_reader.get("diabetes")

When running two instances of this code concurrently, the first one returns ('diabetes',) while the second returns ()

Environment

• QuickUMLS version [e.g. 1.4]
• UMLS version [e.g. 2024AA]

Additional Note
Also posted the bug report in the original repo here