New submission from Marc Garcia: I'm using the csv module from Python standard library, to read a 1.4Gb file with 11,157,064 of rows. The file is the Geonames dataset for all countries, which can be freely downloaded [1].
I'm using this code to read it: import csv with open('allCountries.txt', 'r') as fd: reader = csv.reader(fd, delimiter='\t') for i, row in enumerate(reader): pass print(i + 1) # prints 10381963 print(reader.line_num) # prints 11157064 For some reason, there are around 7% of the rows in the files, that are skipped. The rows doesn't have anything special (most of them are all ascii characters, even if the file is in utf-8). If I create a new file with all the skipped files, and I read it again in the same way, around 30% of the rows are skipped. So many of them weren't returned by the iterator when being a part of a bigger file, but now they are. Note that the attribute line_num has the right number. Also note that if I remove the delimiter parameter (tab) from the reader, and it uses the default comma, the iteration on the reader doesn't skip any row. I checked what I think it's the relevant part of the code [2], but I couldn't see anything that could cause this bug. 1. http://download.geonames.org/export/dump/allCountries.zip 2. https://hg.python.org/cpython/file/tip/Modules/_csv.c#l787 ---------- components: Library (Lib) messages: 280323 nosy: datapythonista priority: normal severity: normal status: open title: csv reader loosing rows with big files and tab delimiter versions: Python 3.5 _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue28642> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com