The interview process was drawn-out, involving two on-site interviews.

For the most part, the questions were very easy. They repeatedly asked about multi-threaded programming, seemingly fishing for some magic answer; I couldn't tell what they wanted to hear.

They also demanded I give a technical presentation and kept pressuring me to present material from my current job, which is, of course, proprietary.

After slogging through a long and repetitive interview process, they chose not to extend an offer, which was probably lucky for me.

However, they never bothered to notify me of their decision after taking a day and a half of my time, plus making me give a presentation! This is incredibly insulting.

How hard is it to write a two-line email saying, "Thank you for your time and interest; we've decided to focus on other candidates?"

This simple program is not thread-safe.

Make it thread-safe.