Reading rather large JSON files [duplicate]

Question

Possible Duplicate:
Is there a memory efficient and fast way to load big JSON files?

So I have some rather large json encoded files. The smallest is 300MB, but this is by far the smallest. The rest are multiple GB, anywhere from around 2GB to 10GB+.

So I seem to run out of memory when trying to load the file with Python. I'm currently just running some tests to see roughly how long dealing with this stuff is going to take to see where to go from here. Here is the code I'm using to test:

from datetime import datetime import json  print datetime.now()  f = open('file.json', 'r') json.load(f) f.close()  print datetime.now() 

Not too surprisingly, Python gives me a MemoryError. It appears that json.load() calls json.loads(f.read()), which is trying to dump the entire file into memory first, which clearly isn't going to work.

Any way I can solve this cleanly?

I know this is old, but I don't think this is a duplicate. While the answer is the same, the question is different. In the "duplicate", the question is how to read large files efficiently, whereas this question deals with files that won't even fit in to memory at all. Efficiency isn't required.

Answer 1

The issue here is that JSON, as a format, is generally parsed in full and then handled in-memory, which for such a large amount of data is clearly problematic.

The solution to this is to work with the data as a stream - reading part of the file, working with it, and then repeating.

The best option appears to be using something like ijson - a module that will work with JSON as a stream, rather than as a block file.

Edit: Also worth a look - kashif's comment about json-streamer and Henrik Heino's comment about bigjson.