PHP file() vs fopen()+fgets() perf

Question

I am in process of rewriting some scripts to parse machine generated logs from perl to php The files range from 20mb~400mb I am running into this problem to decide if I should use file() or fopen()+fgets() combo to go through the file for some faster performance.

Here is the basic run through, I check for file size before opening it, and if file is larger than 100mb(pretty rare case, but it does happen from time to time) I will go the fopen+fgets route since I only bumped the memory limit for the script to 384mb, any file larger than 100mb will have chance causing fatal error. Otherwise, I use file().

I am only going through the file once from beginning to the end in both method, line by line.

Here is the question, is it worth it to keep the file() part of the code to deal with the small files? I don't know how exactly file() (i use the SKIP_EMPTY_LINE option as well) works in php, does it map the file into the memory directly or does it shove line by line into the memory while going through it? I ran some benchmark on it, performance is pretty close, average difference is about 0.1s on 40mb file, and file() has advantage over fopen+fgets about 80% of the time(out of 200 test on the same fileset).

Dropping the file part could save me some memory from the system for sure, and considering I have 3 instance of the same script running at the same time, it could save me 1G worth of memory on a 12G system that's also hosting the database and other crap. But I don't want to let the performance of the script down also, since there is like 10k of these logs coming in per day, 0.1s difference actually adds up.

Any suggestion would help and TIA!

Answer 1

I would suggest sticking with one mechanism, like foreach(new \SplFileObject('file.log') as $line). Split your input files and process them in parallel, 2-3x per CPU core. Bonus: lower priority than database on same system. In PHP, this would mean spawning off N copies of the script at once, where each copy has its own file list or directory. Since you're talking about a rewrite and IO performance is an issue, consider other platforms with more capabilities here, eg Java 7 NIO, nodejs asynchronous IO, C# TPL.