Serhiy Storchaka <storch...@gmail.com> added the comment: > It's under 64-bit Linux, Intel Core i5 CPU. Are you sure you're testing > in non-debug mode?
I use 32-bit Linux. > That said, the numbers under Windows suggest me that Eli's original idea > (append and then join at the end) would be more robust. I agree, it would be more robust, but much more complex solution. I will try to implement this approach too. Victor Stinner in their experiments with formatting preferred overallocation approach (_PyUnicodeWriter), therefore, the solution probably will be a hybrid. However, even in itself the patch deserves attention. It not only significant speeds up writing under Linux, but also speeds up the initialization, which leads to faster reading. ./python -m timeit -s "import io; d=(b'a'*99+b'\n')*10000" "s=io.BytesIO(d); r=s.readline" "while r(): pass" Unpatched: 100 loops, best of 3: 5.92 msec per loop Patched: 100 loops, best of 3: 3.95 msec per loop I will try to preserve this advantage. > By the way, here is Matt Mackall's take on realloc(): Note, that list also uses realloc() inside and therefore you get the same behavior with other constant factor. Actually, appending to a list less than sizeof(void*) bytes at a time you will run into this sooner. Perhaps this is the cause that append/join approach under Windows slower than under Linux. Thank you for measurements, this shows the scale of the issue. ---------- _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue15381> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
