I would like to use python to make system calls to programs and time them. From the Linux command line if you type:
$ time prog args
You get something along the lines of:
real 0m0.110s user 0m0.060s sys 0m0.024s
if you do a 'man time', it states that you can type:
$ time -f "%E" prog args
in order to format to get only display the elapsed time. This does not work in the shell. I beleive it doesn't work because bash must have its own time function. If you type:
$/usr/bin/time -f "%E" prog args
you get the expected output as stated in the man pages.
I want the bash time because it seems to be more accurate. My problem is, when you try to use the 'time prog args' command from python, it doesn't behave the same way as when you type it in.
Code below to see what I'm doing (Please excuse the sloppiness):
#!/usr/bin/env python """Quick & Dirty script to time program execution for multiple inputs. Saves the results as a .csv for importing into excel.""" import subprocess timing = 'time -f "%E" ' program = 'java smartfib ' filename = 'smarttimes.csv' #arglist = [0, 10, 20, 30, 31, 32, 33, 34, 35] #arglist = [0, 2, 3, 5] arglist = range(50) timelist = list() #run the program with the specified input values for arg in arglist: cmd = timing + program + str(arg) pipe = subprocess.Popen(cmd, shell = True, bufsize = 256, stderr = subprocess.PIPE, stdout = subprocess.PIPE) [answer,times] = pipe.communicate() #read from pipe #print times if(int(answer) < 0): print "overflow occured at fib(%d)!\n" %arg break #save (n, [time it takes to complete] as a tuple in a list) timelist.append([arg,times]) csv = list() #list for formatted comma separated values for excel for item in range(len(timelist)): csv.append( str(timelist[item]) + "," + timelist[item][2:].strip('\n') ) results = file(filename,'w') results.write('n,time(in s)\n') for item in range(len(csv)): results.write(csv[item]+'\n') results.close() def getTimeInSeconds(self, timestring): pass