preg_split（）：主题太长了

I'm trying to parse a file content into an array, actually the preg_match works well but with a large file it throws me the follow error:

Warning: preg_split(): Subject is too long in /var/www/html/script.php on line 81

I'm trying with this code:

$fileLines = file($file);
    foreach ($fileLines as $line) {
        $rows = preg_split('/
/', $line);
        $rowCount = 0;
        // THEN I PROCESS THE ROWS
    }
}

The actual file size is almost 2.5Gb, and I think is not a memory problem because I already increase the memory in the VPS and changed the configuration files.

Any idea?

You should read line by line:

$handle = fopen("inputfile.txt", "r");
if ($handle) {
    while (($line = fgets($handle)) !== false) {
        // process the line read.
    }
    fclose($handle);
} else {
    // error opening the file.
} 

No matter how big is your file, you are going to be able to process it.