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# maximum capability of system
user@ubuntu:~$ cat /proc/sys/fs/file-max
708444

# available limit
user@ubuntu:~$ ulimit -n
1024

# To increase the available limit to say 200000
user@ubuntu:~$ sudo vim /etc/sysctl.conf

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import java.util.Random;

/**
 *
 * @author Vijini
 */

//Main class
public class SimpleDemoGA {

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Safest way to clean up boot partition - Ubuntu 14.04LTS-x64

Reference

Case I: if /boot is not 100% full and apt is working

1. Check the current kernel version

$ uname -r 

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Sample config for 2 million web socket connection

    sysctl -w fs.file-max=12000500
    sysctl -w fs.nr_open=20000500
    # Set the maximum number of open file descriptors
    ulimit -n 20000000

    # Set the memory size for TCP with minimum, default and maximum thresholds 
 sysctl -w net.ipv4.tcp_mem='10000000 10000000 10000000'

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Latency Comparison Numbers
--------------------------
L1 cache reference                           0.5 ns
Branch mispredict                            5   ns
L2 cache reference                           7   ns                      14x L1 cache
Mutex lock/unlock                           25   ns
Main memory reference                      100   ns                      20x L2 cache, 200x L1 cache
Compress 1K bytes with Zippy             3,000   ns        3 us
Send 1K bytes over 1 Gbps network       10,000   ns       10 us
Read 4K randomly from SSD*             150,000   ns      150 us          ~1GB/sec SSD

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Advanced Functional Programming with Scala - Notes

Copyright © 2017 Fantasyland Institute of Learning. All rights reserved.

1. Mastering Functions

A function is a mapping from one set, called a domain, to another set, called the codomain. A function associates every element in the domain with exactly one element in the codomain. In Scala, both domain and codomain are types.

val square : Int => Int = x => x * x

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# Tweaked from http://tomislavsantek.iz.hr/2011/03/moving-mysql-databases-to-ramdisk-in-ubuntu-linux

# Log in as root
# Mount ramdisk folder in RAM
mkdir /tmp/ramdisk
mount -t tmpfs -o size=128M tmpfs /tmp/ramdisk/

# Move MySQL data
mv /var/lib/mysql /tmp/ramdisk/mysql
ln -s /tmp/ramdisk/mysql/ /var/lib/mysql