Thirumal Venkat zapstar

How to get a stack trace for each thread in a running python script

Sometimes a python script will simply hang forever with no indication of where things went wrong. Perhaps it's polling a service that will never return a value that allows the program to move forward. Here's a way to see where the program is currently stuck.

Install gdb and pyrasite

Install gdb.

# Redhat, CentOS, etc

Latency numbers every programmer should know

L1 cache reference ......................... 0.5 ns
Branch mispredict ............................ 5 ns
L2 cache reference ........................... 7 ns
Mutex lock/unlock ........................... 25 ns
Main memory reference ...................... 100 ns             
Compress 1K bytes with Zippy ............. 3,000 ns  =   3 µs
Send 2K bytes over 1 Gbps network ....... 20,000 ns  =  20 µs
SSD random read ........................ 150,000 ns  = 150 µs

Read 1 MB sequentially from memory ..... 250,000 ns = 250 µs

	import javax.crypto.Cipher;
	import java.security.NoSuchAlgorithmException;

	public class KeyLengthDetector {
	public static void main(String[] args) {
	int allowedKeyLength = 0;

	try {
	allowedKeyLength = Cipher.getMaxAllowedKeyLength("AES");
	} catch (NoSuchAlgorithmException e) {