python - Why file read is faster on reading again? - 


size = 1<<16 def justread(file):     open(file, 'rb') f:         while f.read(size):             pass

the first time run function on 700mb file took 19 secs. when repeated
reading same file again time took dropped 0.5secs.
repeated many files , results similar.
going on here?

the operating system caches file in memory upon first read, , second time read memory instead of hard disk. of course memory faster.


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