I've ported a small script from C to D. The original C version takes
roughly 6.5 minutes to parse a 12G file while the port originally took
about 48 minutes. My naïve attempt to improve the situation pushed it
over an hour and 15 minutes. However, replacing std.stdio:File with
core.stdc.stdio:FILE* and changing my output code in this latest version
from:
outputFile.writefln("%c\t%u\t%u\t%d.%09u\t%c", ...)
to
fprintf(outputFile, "%c,%u,%u,%llu.%09llu,%c\n", ...)
reduced the processing time to roughly 7.5 minutes. Why is
File.writefln() so appallingly slow? Is there a better D alternative?
I tried std.io but write() only outputs ubyte[] while I'm trying to
output text so I abandoned idea early. Now that I've got the program
execution time within an acceptable range, I tried replacing
core.stdc.fread() with std.io.read() but that increased the time to 24
minutes. Now I'm starting to think there is something seriously wrong
with my understanding of how to use D correctly because there's no way
D's input/output capabilities can suck so bad in comparison to C's.
