import os, datetime
import pylab as pl

def memory_usage_resource():
    import resource
    rusage_denom = 1024.
    if sys.platform == 'darwin':
        # ... it seems that in OSX the output is different units ...
        rusage_denom = rusage_denom * rusage_denom
    mem = resource.getrusage(resource.RUSAGE_SELF).ru_maxrss / rusage_denom
    return mem

def memory_usage_psutil():
    import psutil
    process = psutil.Process(os.getpid())
    mem = process.get_memory_info()[0] / float(2 ** 20)
    return mem

def memory_usage_ps():
    import subprocess
    out = subprocess.Popen(['ps', 'v', '-p', str(os.getpid())],
    stdout=subprocess.PIPE).communicate()[0].split(b'\n')
    vsz_index = out[0].split().index(b'RSS')
    mem = float(out[1].split()[vsz_index]) / 1024
    return mem

mem_resource = []
mem_psutil = []
for i in range(1, 21):
    a = np.zeros((1000 * i, 100 * i))
    mem_resource.append(memory_usage_resource())
    mem_psutil.append(memory_usage_psutil())

pl.plot(mem_resource, color='blue', label='resource', lw=4)
pl.plot(mem_psutil, color='red', label='psutil', lw=4)
pl.legend(loc='upper left')
pl.ylabel('Memory usage in MB')
pl.savefig('resource_vs_psutil.png')
pl.show()

start = datetime.datetime.now()
for _ in range(100):
    memory_usage_ps()
ps_timing = (datetime.datetime.now() - start).total_seconds()

start = datetime.datetime.now()
for _ in range(100):
    memory_usage_psutil()
psutil_timing = (datetime.datetime.now() - start).total_seconds()

start = datetime.datetime.now()
for _ in range(100):
    memory_usage_resource()
resource_timing = (datetime.datetime.now() - start).total_seconds()

pl.bar(range(3), [ps_timing, psutil_timing, resource_timing])
pl.xticks(np.arange(3) + .5, ['ps', 'psutil', 'resource'])
pl.ylabel('Time (in seconds)')
pl.title('Time to make 100 memory measurements')
pl.savefig('time_100_measurements.png')
pl.show()