
I am a computer scientist working for a major industrial research lab.
English is still the primary language for technology research publications, and will continue to be so for the near future. So don't worry about needing to read foreign journals. Yes some French or German or Japanese might help you find a few more obscure things, but generally if the work is worthwhile it eventually gets published in English.
However, personally I think you should learn Mandarin Chinese. Why?
1) There's a gigantic pool of IT research talent in China that we're only beginning to tap. They publish primarily in English, but their spoken English is generally poor with some exceptions. It's a tremendous benefit to know at least some Chinese in order to be able to socialize with your Chinese colleagues at a conference or when visiting. And I'm fairly certain that if you make a career in research in the next 50 years, you will be visiting and possibly living in the PRC at some point.
2) Research isn't for everyone. If you discover this at an awkward time in your career, it helps to have other skills to fall back on. Being able to speak Chinese is already a significant career asset, and this is likely to continue.
3) Spoken Chinese is a great language to learn, because it challenges a native-English-speaker's conceptions of grammar and meaning. It forced me to think about language in a whole new way, similar to how Prolog completely broke my brain as a sophomore CS undergrad.
All that said, Chinese fluency requires 8+ years of intensive education and immersion to develop; you will most likely never become as proficient in it as you might in a Western language.
One of the most overlooked advantages to computers is... If they do foul up, there's no law against whacking them around a little. -- Joe Martin