Really stop Clojure's infinite loop future with future-cancel

If you like me, executed future-cancel and the future is still running. This blog post is for you.

I suppose your code is something similar to this:

(def f (future (while true (your-function ... ))))

(future-cancel f)

All you have to do as describe in this SO comment is to replace true with (not (Thread/interrupted)). Example:

(future (while (not (Thread/interrupted)) (your-function ... )))

Because future-cancel will send interrupt signal to the future, Thread/interrupted will be changed to true. Now your future-cancel should work as expected.

Handy note from The Future of Ruby Performance Tooling talk

GoRuCo 2014 - The Future of Ruby Performance Tooling by Aaron Quint

It introduces a few numbers of promising Ruby performance tooling. I'll definitely refer back to this post when I do performance optimization.

• rblineprof
• ppprofiler
• stackprof
• stackprof-remote
• objspace_viewer

[PostgreSQL] See SQL queries (without restarting the server!)

1. In postgresql.conf (probably under /etc/postgres/...), uncomment log_statement and set to 'all'

log_statement = 'all'

2. To reload config, sending SIGHUP to postgres server by going to psql shell and execute:

select pg_reload_conf();

    There's an another way to send SIGHUP, please refer to the link below

3. Observe the queries at postgresql.log (probably under /var/log/...)
4. To disable, comment out log_statement and reload config again

log_statement, reloading postgresql config

Credit: http://stackoverflow.com/a/8208376

RSpec 3 matcher equivalent to =~

contain_exactly

Example:
  expect([1,2]).to contain_exactly(2,1)

Credit: match_array matcher now available as contain_exactly

Run clojure.test inside Light Table

Simply add a line

(run-tests)

and evaluate source code normally (cmd+shift+enter). See the output in the console.

Clone a PostgreSQL database

At some point in development, you may want to make a copy of your existing development database to play with an unstable new feature. Postgres makes it super trivial to do that by allow us to create a new database by using existing database as a template.

In postgres console, run

=# CREATE DATABASE new_database_name WITH TEMPLATE original_database_name;

Boom!, you got a cloned database named new_database_name.

Credit: Creating a copy of a database in Postgres
PS: I've seen a convenient way to make a clone across remote server too. (Haven't try) How to copy postgres database to another server

Update Aug 27, 2015:
Instead of running command in psql, we can use createdb with -T flag like so

$ createdb -T original_database_name new_database_name

Credit: http://stackoverflow.com/a/6739995 

Tmux: open new pane/window base on current directory

You need to rebind your short key with argument -c "#{pane_current_path}"

E.g.
New vertical pane
Default: bind % split-window -h
To: bind % split-window -h -c "#{pane_current_path}"

New horizontal pane
Default: bind '"' split-window
To: bind '"' split-window -c "#{pane_current_path}"

New window
Default: bind c new-window
To: bind c new-window -c "#{pane_current_path}"

Credit: Tmux forgets the directory where the session was created