Create 1% Sample Using Multiprocessing in Python
Disclaimer: I have never worked with multiprocessing, so I can't comment on that implementation.



Handling Files

I noticed at the top of the file you open a file, but never close it. (For the argument that an anonymous file is closed right after the statement is executed, see this post). Leaving files open is not a good idea. You should always close your files; leaving files open can slow down your program. I'd change that line to the code below:

with open('Subsets/unique_ids_final.txt') as file:
    uid = list(line.strip() for line in file.readlines())


While it is more typing, with automatically closes the file after the inner code is run.

List Comprehension

A couple of you for loops can be reduced to one line statements. You can create a list directly with a for loop. Take a look:

tlines = [line for line in lines if line.split('*')[30] in id_pct1]


Same with jobs:

jobs = [
    pool.apply_async(worker, (chunk_start, chunk_size, q))
    for chunk_start, chunk_size in chunkify('myfile.txt')
]


One line if statements

This 

if m == 'kill': break


should be this

if m == 'kill':
    break


Even though it's one line, one word, you should still indent.

Docstrings

You should include docstrings when you write functions, methods, and classes. They are used to provide more description. Take a look:

def worker(chunk_start, chunk_size, q) -&gt; List[str]:
    """
    Read original file and write 1% sample using multiprocessing

    :param &lt;type&gt; chunk_start: &lt;description&gt;
    :param &lt;type&gt; chunk_size: &lt;description&gt;
    :param &lt;type&gt; q: &lt;description&gt;

    :return: List[str]
    """


I had trouble following your code and understanding what variables were what types. Essentially, when labeling parameters in your docstrings, the format I used goes as follows:

:param &lt;type of parameter&gt; &lt;name of parameter&gt;: &lt;description about parameter&gt;


And returns are as follows:

:return: &lt;type to return&gt;


If you want docbuilders, consider using sphinx.

Type Hints

These help portray what types are accepted and returned by a function/method. Take a look:

def add(x: int, y: int) -&gt; int:
    return x + y


While this is a very straightforward example, the idea is still there.

Variable/Parameter Names

These should be in snake_case, not mixedCase.

chunkStart -&gt; chunk_start
chunkSize -&gt; chunk_size