Jonah Hill's movie 'Mid90s' is his ''best friend''.

The 34-year-old actor feels ''vulnerable'' now his directorial debut has been released because he turned to the project in order to vent his feelings and emotions over a long period of time.

He said about the movie: ''It's my best friend. It's literally my best friend. Like, anytime I was sad, angry, happy, lonely, I'd go in my room and I'd just write, spend time with this, cater to it, build it.

''And then now it goes off into the world and someone can...beat it and punish it or hug it. This kind of thing is vulnerable in a way I've never experienced before.''

And Jonah - whose brother, Jordan Feldstein, died last December while he was working on the movie - credits the film for ''saving [his] life'' and admitted it was hard to say goodbye once the final cut was complete.

He told the new issue of America's GQ magazine: ''The timing was really fucked. So it was on my mind every day. Thank God for the movie. The movie saved my life in a lot of different ways...

''That's why it was hard to say goodbye.''

Early screenings of 'Mid90s' carried a dedication to Jordan, but the 'Moneyball' star ultimately decided to remove the message.

He said: ''When I was showing it to people I know intimately, they understood. But when we started showing it to an audience, they're like, 'What?' It's asking a lot of an audience to understand the intimate details of my life. The film is for him, but I took out the straight dedication.''

While the lead character in the movie, Stevie, has a complicated relationship with his own older brother, Jonah insists the film isn't a ''biopic'' of his relationship with Jordan.

He said: ''I definitely learned about hip-hop from my brother. I would sneak into his room, and that's how I learned about everything. I had better taste in film and music than I ever would have had, because he was six years older and had great taste. And we fought like brothers fight, but it's not a biopic of our life together.''