CODEWITHSUNDEEP
python
thecoder
thecoder

Reputation: 45

How do I speed up parsing large log files in python?

I need to run a parser on .gz files that contain log files for a project I am working on. Once extracted, each log file is roughly 800MB, and each .zip file can contain up to 20 of them.

In total, I would need to parse through as much as 20GB of raw text files in a single shot. I have no control over the structure of the log/.gz files as these are downloaded from the company's AWS server.

Within these log files, I need to look for a particular code, and if the code exists within the line, I need to extract the relevant data and save it to a csv file.

Right now, I am searching through line by line and as expected, a single file takes as long as 10min to complete, timed using timeit

with gzip.open(file_location, 'rb') as f:
    for line in f:
        line_string = line.decode().strip()
        if self.config_dict["log_type"] in line_string:
            log.append(line_string)

Is there any way I can speed up the parsing?

Edit: To give context, this is how a single line of the log file may look like

8=FIX.4.49=28935=834=109049=TESTSELL152=20180920-18:23:53.67156=TESTBUY16=113.3511=63673064027889863414=3500.000000000015=USD17=2063673064633531000021=231=113.3532=350037=2063673064633531000038=700039=140=154=155=MSFT60=20180920-18:23:53.531150=F151=3500453=1448=BRK2447=D452=110=151

Within this, I am checking for a very specific substring, lets say "155=MSFT" and if there is a match, i will add it to a certain list.

Upvotes: 1

Views: 806

Answers (2)

Ry-
Ry-

Reputation: 224913

I would outsource the work to something faster than Python. zgrep(1) exists exactly for this task:

import subprocess

search_process = subprocess.Popen(
    ["zgrep", "-F", "--", self.config_dict["log_type"], file_location],
    stdin=subprocess.DEVNULL,
    stdout=subprocess.PIPE,
    stderr=subprocess.DEVNULL,
    encoding="utf-8",
)

log.extend(search_process.stdout)

if search_process.wait() != 0:
    raise Exception(f"search process failed with code {search_process.returncode}")

Upvotes: 1

monkut
monkut

Reputation: 43840

One example of processing multiple files with multiprocessing Pool

from multiprocessing import Pool

def process_log(filepath: str, log_type: str) -> list[str]:
    results = []
    with gzip.open(file_location, 'r') as f:
        for line in f:
            if log_type in line:
                log.append(line.line_stringstrip())
    return results

def process_log_files(log_filepaths: list[str], log_type: str):
    args = [(filepath, log_type) for filepath in log_filepaths]
    with Pool() as pool:
        with open('output.txt', 'w', encoding='utf8') as out:
            for results in pool.starmap(process_log, args):
                for result in results:
                    out.write(result)

Upvotes: 0

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