Yes you are probably right Antti. The input to compress would need 31 TB of memory, and is a text string, while Python 3’s zlib.compress() requires bytes. In other words, this will be the same problem of overallocating memory as Issue 27559.

Pablo: I suggest you carefully look at the code, try to understand what it is doing, eliminating the unnecessary parts, etc. Especially when so many of your reports today involve similar techniques.