profiling bashrc: check for long loading time code

bashprofile.py

import argparse
import heapq

parser = argparse.ArgumentParser(description='Analyze bash start log for speed.')
parser.add_argument('filename', help='often /tmp/bashload.<PID>.log')
parser.add_argument('-n', default=20, help='number of results to show')
args = parser.parse_args()
filename, n = args.filename, int(args.n)

#add following to ~/.bashrc
###BEGIN PROFILING
#PS4='+ $(date "+%s.%N")\011 '
#exec 3>&2 2>/tmp/bashload.$$.log
#set -x

###END PROFILING
#set +x
#exec 2>&3 3>&-

with open(filename, 'r') as f:
    q = []
    prev_time = None
    total = 0
    for line in f.readlines():
        #ignore empty/invalid lines
        if not line or not line.strip():
            continue
        line = line.split()
        if '+' not in line[0] or len(line) < 3:
            continue
        text = ' '.join(line[2:])
        #trim out long lines
        if len(text) > 100:
            text = text[:100]
        #compute diff
        time = float(line[1])
        diff = time - prev_time if prev_time is not None else 0
        total += diff
        prev_time = time
        heapq.heappush(q, (diff, text))

for diff, text in heapq.nlargest(n, q):
    print diff, 's:', text
print 'Total loading time[s]: ', total