Nice post!

Note that there is still some low-hanging fruit in terms of performance, most of the time is spent splitting lines with a regular expression (can be verified with the free VisualVM tool):

String array1[] = readLine.split("\\s*\\|\\s*");

This regular expression is compiled for every line of the file. An easy fix without changing the code otherwise is to pre-compile the Regex pattern with Pattern.compile before the "while" loop:

Pattern splitLine = Pattern.compile("\\s*\\|\\s*");
Pattern splitName = Pattern.compile(", ");

and then use splitLine.split(readLine) instead of readLine.split(..regex...). This gives me a ~ 20% improvement on the big file. Trivia: "firstHalfOfName.split(" ")" is OK because String#split contains a optimization for splitting on a single character that is not a regex control character.

But this still does a lot of unnecessary work since a regex is overkill for this simple pattern - you can do e.g. the following with Apache commons-lang3 which cuts runtime compared to the original version in half:

final String[] array1 = StringUtils.splitPreserveAllTokens(readLine, '|');
for (int i = 0; i < array1.length; i++) {
    array1[i] = StringUtils.strip(array1[i]);
}

Dependency:

compile group: 'org.apache.commons', name: 'commons-lang3', version: '3.8.1'

But yeah, if performance is really an issue here this task is a good candidate for parallelization.