Get top 10 lines in large file

gistfile1.txt

import unittest
import sys, array, tempfile, heapq
import io
from itertools import islice

NUM_LINES_IN_MEM_PER_FILE = 100000
NUM_LINES_IN_EACH_FILE = 1000000

class SortLargeFile:
    def intsfromfile(self, f):
        while True:
            next_n_lines = list(islice(f, NUM_LINES_IN_MEM_PER_FILE))
            if not next_n_lines:
                break
            for line in next_n_lines:
                yield line
        f.close()    

    def saveToTemp(self, arr):
        print("size of the arr {}".format(len(arr)))
        f = tempfile.TemporaryFile(mode="r+")
        li = list(sorted(arr))
        f.writelines(i for i in li)
        f.seek(0)
        return self.intsfromfile(f)     

    def sort(self, source):
        print('source {}'.format(source))
        iters = []
        with open(source, 'r') as sf:
            arr = []
            for line in sf:
                arr.append(line)
                if len(arr) >= NUM_LINES_IN_EACH_FILE:
                    iters += self.saveToTemp(arr)
                    arr = []
            if arr:        
                iters += self.saveToTemp(arr)        
        
        print('Number of tmp files', len(iters))
        last = None
        count = 0
        top_ten = []
        for x in heapq.merge(*iters):
            count += 1
            if not last or last != x:
                if not last:
                    last=x.strip('\n')
                if len(top_ten) < 10:
                    heapq.heappush(top_ten, (count,last))
                elif top_ten[0][0] < count or (top_ten[0][0] == count and top_ten[0][1] < last):
                    heapq.heappushpop(top_ten, (count,last))    
                last = x
                count = 0

        if len(top_ten) < 10 or top_ten[0][0] < count:
            heapq.heappushpop(top_ten, (count,last))
        
        while top_ten:
            val = heapq.heappop(top_ten)
            print(val[1], val[0])  

slf = SortLargeFile()
slf.sort('/Users/drichards/grabbag/test_mocking.py/hash_keys_small.txt')