This glitch is pretty annoying. You’re following a log, while connected to a server (through ssh), and after a while, your ssh connection hangs. The solution?.

Fire up Terminal, and type the following: nano ~/.ssh/config

Once there, fill up the following:

ServerAliveInterval 300
ServerAliveCountMax 120

That should keep your connection alive for the next 10 hours, without further issues.

The following snippet of code.. which is super interesting, is based on this post. This allows to dispatch a block, on Main Thread, once two async operations are completed.

dispatch_group_t group = dispatch_group_create();

dispatch_group_async(group, dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^ {
  NSLog(@"Block1");
  [NSThread sleepForTimeInterval:5.0];
  NSLog(@"Block1 End");
});

dispatch_group_async(group, dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^ {
  NSLog(@"Block2");
  [NSThread sleepForTimeInterval:8.0];
  NSLog(@"Block2 End");
});

dispatch_group_notify(group, dispatch_get_main_queue(), ^ {
  NSLog(@"Block3 :: %d", [NSThread isMainThread]);
});

dispatch_release(group);

This humble wordpress blog is running on an AWS micro instance. We’ve got somewhere around 1k visitors each month, which is pretty awesome. But… to my surprise, the whole system is using over 14 million I/O operations.

I suspected there was something wrong with this… so i proceeded to do a small research. By means of the application ‘iotop’, i managed to spot the I/O hog: apache!.

Specifically, i ran iotop with the following parameters:

sudo iotop -a -P

I ran a quick search on google, and found this post.  (Thank you George, for sharing your solution!).

Long short story, Apache’s APC plugin was using a memory mapped file, and it was writing… almost all the time. The solution?. Edit your /etc/php.d/apc.ini file, and make sure that the mmap_file_mask parameter is se to use Shared Memory, as follows:

apc.mmap_file_mask=/apc.shm.XXXXXX

That should fix it!

I’ve recently lantean.co to AWS EC2. Amazon offers a free EC2 instance for a year…. so i decided to give it a shot.

The main reason i had to migrate to a self managed hosting is simple. Shared Hostings don’t allow you to fine tune several settings, such as the PHP Memory, and you might event not be able to login using ssh. What did i need to do?. It’s simple… let’s see…

Setting up the Environment

1. Signup at Amazon Web Services. You’ll need a credit card.
2. Create a new EC2 instance. Select ‘Micro’ as the type.
3. Select the Amazon AMI. (I don’t trust 3rd party images!).
4. Follow the wizard, and generate the SSH private / public keys.
5. Setup the firewall, so only IP’s in your C class can connect through SSH, and everyone can hit the port 80.
6. Connect to your box!

   ssh -i certificate.pem ec2-user@[elastic-ip]

7. Setup a password for your root user

   su passwd

8. Install Apache

   yum install httpd
   service httpd start
   chkconfig httpd on

9. Install PHP

   yum instlal php php-mysql

10. Install mySQL

    yum install mysql-server
    service mysqld start
    chkconfig mysqld on

11. Secure mySQL

    mysql_secure_installation

12. Install APC

    yum install php-pecl-alc

Setting up Apache

Assuming we’re not gonna host just a single website, but a couple of them… we’re gonna need to setup Virtual Hosts. With VirtualHosts you can serve as many domains as you need, using a single apache installation. Steps!

1. Log into your instance and type… (replace domain.com with your own domain):

   su
   mkdir -p /var/www/domain.com/public_html
   mkdir /etc/httpd/conf.d/domain.com.conf
   nano /etc/httpd/conf.d/domain.com.conf/httpd.conf
   Add the following lines:
   ServerAdmin your-mail@domain.com
   DocumentRoot /var/www/domain.com/public_html
   ServerName www.domain.com
   ServerAlias *.domain.com
   ErrorLog /var/www/domain.com/error.log
   CustomLog /var/www/domain.com/requests.log combined

2. Enable htaccess in your virtual hosts:

   nano /etc/httpd/conf/httpd.conf
   AllowOverride All

3. Enable logrotate:

   nano /etc/logrotate.conf
   Add the following lines:
   /var/log/httpd/*log
   /var/www/*/*log
   {
   size 5M
   missingok
   notifempty
   sharedscripts
   delaycompress
   postrotate
   /sbin/service httpd reload > /dev/null 2>/dev/null || true
   endscript
   }

Setting up mySQL

At last!. Let’s see how to create a mySQL database, add a new user, and how to import your mySQL dump, using nothing but bash.

1. Create a new database and a new user

   mysql -u root -p << You will be asked for your mySQL root-password!
   create database wordpress;
   create user 'wordpress'@'localhost' identified by 'password';
   grant all privileges on wordpress.* to wordpress@localhost;
   flush privileges;

2. Import a database dump

   mysql -p -u wordpress wordpress < database_dump.sql

  I hope you found this short guide helpful!

I’m writing this, right here, so i know where to pick it up next time i get the same issue. Thanks to Jonathan, who wrote this awesome post, and saved me quite a lot of time.

Long short story, it seems there is a buggy library on OSX, that produces broken SSL connections to hang for quite some time. Workaround?

sudo port install neon

That should upgrade the faulty library, and fix this annoying issue.