High Kernel CPU when running multiple python programs

Question

I developed a python program that does heavy numerical calculations. I run it on a linux machine with 32 Xeon CPUs, 64GB RAM, and Ubuntu 14.04 64-bit. I launch multiple pyth

Answer 1

If the problem exists in kernel, you should narrow down a problem using a profiler such as OProfile or perf.

I.e. run perf record -a -g and than read profiling data saved into perf data using perf report. See also: linux perf: how to interpret and find hotspots.

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In your case high CPU usage is caused by competition for /dev/urandom -- it allows only one thread to read from it, but multiple Python processes are doing so.

Python module random is using it only for initialization. I.e:

$ strace python -c 'import random;
while True:
    random.random()'
open("/dev/urandom", O_RDONLY)     = 4
read(4, "\16\36\366\36}"..., 2500) = 2500
close(4)                                   <--- /dev/urandom is closed

You may also explicitly ask for /dev/urandom by using os.urandom or SystemRandom class. So check your code which is dealing with random numbers.