A lot of effort when into the MCE module to assist bioinformaticians in regards to using multiple cores. MCE includes logic allowing one to process input by specifying a record separator. In the OP's case, to anchor "@" at the start of the line: "\n@". Workers receive record(s) beginning with "@", not "\n@".

Basically, MCE wraps serial code with little code to consume multiple cores.

Regards, Mario.