[
https://issues.apache.org/jira/browse/COUCHDB-1118?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13015204#comment-13015204
]
Adam Kocoloski commented on COUCHDB-1118:
-----------------------------------------
Hi Filipe, which version are you proposing to commit?
There must be some overhead associated with using a NIF. I thought in at least
one version of Paul's work the overhead made the NIF version slower at decoding
very small documents than pure Erlang. Is that no longer the case? Also, has
anyone studied the impact that working with very large JSON bodies has on the
soft real-time properties of the Erlang VM? Do you know what kind of
throughput you see in terms of MB/sec? I guess if that number is large enough
then any reasonably-sized JSON body (even a very big batch of KV pairs returned
from a map_docs call) will be processed without mucking up the scheduling too
much.
> Adding a NIF based JSON decoding/encoding module
> ------------------------------------------------
>
> Key: COUCHDB-1118
> URL: https://issues.apache.org/jira/browse/COUCHDB-1118
> Project: CouchDB
> Issue Type: Improvement
> Components: Database Core
> Reporter: Filipe Manana
> Fix For: 1.2
>
>
> Currently, all the Erlang based JSON encoders and decoders are very slow, and
> decoding and encoding JSON is something that we do basically everywhere.
> Via IRC, it recently discussed about adding a JSON NIF encoder/decoder.
> Damien also started a thread at the development mailing list about adding
> NIFs to trunk.
> The patch/branch at [1] adds such a JSON encoder/decoder. It is based on Paul
> Davis' eep0018 project [2]. Damien made some modifications [3] to it mostly
> to add support for big numbers (Paul's eep0018 limits the precision to 32/64
> bits) and a few optimizations. I made a few corrections and minor
> enhancements on top of Damien's fork as well [4]. Finally Benoît identified
> some missing capabilities compared to mochijson2 (on encoding, allow atoms as
> strings and strings as object properties).
> Also, the version added in the patch at [1] uses mochijson2 when the C NIF is
> not loaded. Autotools configuration was adapted to compile the NIF only when
> we're using an OTP release >= R13B04 (R13B03 NIF API is too limited and
> suffered many changes compared to R13B04 and R14) - therefore it should work
> on any OTP release > R13B at least.
> I successfully tested this on R13B03, R13B04 and R14B02 in an Ubuntu
> environment.
> I'm not sure if it builds at all on Windows - would appreciate if someone
> could verify it.
> Also, I'm far from being good with the autotools, so I probably missed
> something important or I'm doing something in a not very standard way.
> This NIF encoder/decoder is about one order of magnitude faster compared to
> mochijson2 and other Erlang-only solutions such as jsx. A read and writes
> test with relaximation shows this has a very positive impact, specially on
> reads (the EJSON encoding is more expensive than JSON decoding) -
> http://graphs.mikeal.couchone.com/#/graph/698bf36b6c64dbd19aa2bef634052381
> @Paul, since this is based on your eep0018 effort, do you think any other
> missing files should be added (README, etap tests, etc)? Also, should we put
> somewhere a note this is based on your project?
> [1] - https://github.com/fdmanana/couchdb/compare/json_nif
> [2] - https://github.com/davisp/eep0018
> [3] - https://github.com/Damienkatz/eep0018/commits/master
> [4] - https://github.com/fdmanana/eep0018/commits/final_damien
--
This message is automatically generated by JIRA.
For more information on JIRA, see: http://www.atlassian.com/software/jira
