Originally Posted by theducks
I forget the exact reason for the 100 book confirm. It might have been crash protection and or buffer flush (needed housekeeping).
Yeah it was added because (a) some of the code libraries that calibre uses leak memory like a sieve, and (b) the PDF library particularly is most prone to crashing, and (c) the prompt is necessary to ensure that the database integrity against the user also performing updates at the same time on those books and data getting lost. Because of a and b the process was broken into batches (you can control the batch size yourself in the options for the Extract ISBN plugin) so someone scanning large numbers of books would not see a crash result in *all* of the isbns extracted so far to that point having to be done again, only that batch.
If you are only scanning ePub formats in your library it is very unlikely to crash so you could crank up the batch size a bit. However any other format means either the plugin does a conversion to ePub (which has memory leaks in the conversion pipeline) or in the case of PDF it uses the pdf2html library which while better than previous versions/libraries calibre has used in the past it can still crash or have issues...