a sample script to capture stack data of nginx.

ngx-stacks.py

#! /usr/bin/env python
import os
import sys
import time
import signal
import subprocess

stap_script = """ 
global s;

probe process("/usr/local/nginx/sbin/nginx").function("*") {
	s[sprint_ubacktrace()] <<< 1;		
} 

probe end {
	foreach ([stack] in s+) {
		printf("%s\\n\\n", stack);
	}
}
	
"""

def handler(signum, frame):
    exit()

def print_usage():
    print "nginx-stacks.py"

if __name__ == "__main__": 
    tmp = "stap.tmp" 

    with open(tmp, "w+") as f:   
        f.write(stap_script)
    status3 = 0
    try:
        status3 = os.fork()
    except OSError as e:
        print e 
    if status3 == 0:
        try:
            os.execvp("stap", ['stap',"-o", "nginx.stacks",
				"-v",
				"-d", "/lib64/libc-2.17.so",
				"-s", "32",
				"-D", "MAXTRACE=100",
				"-D", "MAXSTRINGLEN=4096",
				"-D", "MAXMAPENTRIES=10240",
				"-D", "MAXACTION=10000",
				"-D", "STP_OVERLOAD_THRESHOLD=5000000000",
				"%s" % tmp]) 
        except OSError as e:
            print e 
    signal.signal(signal.SIGINT, handler) 
    while True:
        time.sleep(2)