This script does test reads and writes to a file.

file-soak-test.py

#This script does test reads and writes to a file.
#Release under CC0 by Tim Sheerman-Chase, 2014

#This script fails on my computer but not on others. Weird.

import random, time, pickle, sys
import numpy as np

def MultiRead(handle, maxLen):
	buff = []
	while 1:
		if maxLen == 0:
			return b"".join(buff)
		dat = handle.read(maxLen)
		if len(dat) > 0:
			buff.append(dat)
			maxLen -= len(dat)
		else:
			return b"".join(buff)

if __name__=="__main__":

	outfina = "soaktest-native.dat"
	if len(sys.argv)>1:
		outfina = sys.argv[1]

	fi = open(outfina, "w+b")

	globalRandSeed = 0
	random.seed(globalRandSeed)
	np.random.seed(globalRandSeed)
	numBins = 1000
	
	binSizes = [random.randint(0,500000) for i in range(numBins)]
	print("Total test size", sum(binSizes))
	binOffsets = [0, ]
	for bs in binSizes[:-1]:
		val = binOffsets[-1]+bs
		binOffsets.append(val)

	oldData = None
	oldSeed = None

	while 1:
		print("Begin iteration", globalRandSeed, "native")
		globalRandSeed += 1
		random.seed(globalRandSeed)
		np.random.seed(globalRandSeed)

		#Generate new data
		data = []
		for bs in binSizes:
			binDat = np.random.bytes(bs)
			data.append(binDat)

		#Generate write order
		accessOrder = list(range(numBins))[:]
		random.shuffle(accessOrder)

		for count, binNum in enumerate(accessOrder):

			if oldData is not None:
				fi.seek(binOffsets[binNum])
				#readback = fi.read(binSizes[binNum])
				readback = MultiRead(fi, binSizes[binNum])
				checkok = (readback == oldData[binNum])
				if not checkok:
					print("Readback failed. saving to file.", binNum)
					print("Matches", sum([x==y for x, y in zip(readback, oldData[binNum])]))

					if sys.version_info[0] > 2:
						print([c for c in oldData[binNum][:30]], len(oldData[binNum]))
						print([c for c in readback[:30]], len(readback))
					else:
						print([ord(c) for c in oldData[binNum][:30]], len(oldData[binNum]))
						print([ord(c) for c in readback[:30]], len(readback))

					import pickle
					pickle.dump(oldData[binNum], open("expected.dat","wb"), protocol=-1)
					pickle.dump(readback, open("got.dat","wb"), protocol=-1)
					fi.flush()
					exit(0)
				
			fi.seek(binOffsets[binNum])
			fi.write(data[binNum])

		#Flush every tenth interation to see if it makes a difference
		if globalRandSeed % 10 == 0:
			print("Flushing")
			fi.flush()

		oldData = data
		oldSeed = globalRandSeed