android: gson performance

Question

I am trying to use gson to do my object mapping on the android emulator.

It has been ridiculously slow when processing json data around 208 kb. I do not have any hierarchies in my json.

After the object mapping is done, i can see it that gson created around 500 records.

It is taking it over 3 minutes on the android emulator to map the input json.

I have annotated my entity which comprises of strings and couple of floats.

An I missing something?

Any ideas, best practices would greatly help.

Are there any ways of quickly object mapping the json data?

        URL myURL = new URL(url);
        /* Open a connection to that URL. */
        URLConnection ucon = myURL.openConnection();
        /*
         * Define InputStreams to read from the URLConnection.
         */
        InputStream is = ucon.getInputStream();
        InputStreamReader reader = new InputStreamReader(is);
        long tickCount = System.currentTimeMillis();
        Policy[] policies = new Gson().fromJson(reader, Policy[].class);
        long endCount = System.currentTimeMillis() - tickCount;
        Log.d("Time to pull policies in milliseconds", "" + endCount);

Please don't use the Android emulator for performance measurement. It's performance model is significantly different from that of a real device. — Jesse Wilson, Feb 21 '13 at 03:04

score 5 · Answer 1 · edited May 23 '17 at 12:16

I've seen questions like this come up before, and the general consensus is that Jackson is much faster than Gson. See the following links for more information:

Here is one which specifically discusses Android: http://ubikapps.net/?p=525

score 4 · Answer 2 · answered Apr 25 '11 at 21:50

4

Have you tried the mixing the GSON streaming parser with the Gson object? http://sites.google.com/site/gson/streaming (look for the Mixed read example).

This approach may help since Gson reads in an entire parse tree and then acts on it. With a large array list, reading in all elements and attempting to parse may cause lot of memory swaps (or thrashing). This approach will read in one element at a time.

Hope this helps.

answered Apr 25 '11 at 21:50

Joel

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+1 - the DOM approach on GSON is quick to implement, but really slow to process large responses. I use it for prototypes, and then optimise down to the Streaming method for production. I think more people need to realise GSON is not so slow, its how you use it (not saying it is the fastest, just that many don't use streaming) – Richard Le Mesurier Jun 20 '12 at 09:15

score 2 · Answer 3 · answered Feb 15 '11 at 22:34

2

You'd probably get better performance if you wrapped that InputStream in a BufferedInputStream with a nice big buffer...

3 minutes is insane. I seldom run the emulator but I have an app with a ~1.1MB JSON asset and that takes around 5 seconds to load and process on hardware.

(Which is still far too long, but still).

answered Feb 15 '11 at 22:34

Reuben Scratton

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I am fighting with the same issue. Do you have an online tutorial which descripes your solution? – nano_nano Dec 23 '13 at 13:04

score 1 · Answer 4 · answered Feb 20 '13 at 15:56

1

I've found that I can speed up gson.fromJSON quite considerably by not modelling all the elements in the JSON that I won't need. GSON will happily fill in only what is specified in your response classes.

answered Feb 20 '13 at 15:56

Nova Entropy

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score 1 · Answer 5 · answered Sep 03 '16 at 05:03

I have found that CREATING a Gson instance is a very expensive operation, both in terms of CPU used and memory allocated.

Since Gson instances are thread-safe, constructing and reusing a single static instance pays off, especially if you are serializing / deserializing often.

android: gson performance

5 Answers5

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