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https://issues.apache.org/jira/browse/COUCHDB-1118?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13015205#comment-13015205
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Paul Joseph Davis commented on COUCHDB-1118:
--------------------------------------------
I need to go back and look at the numbers for encoding/decoding again to try
and pin down what the actual overhead/cost is for each method. I do remember
there being some issues with tiny docs, but they were extremely tiny. Anything
of any actual size is probably going to be faster in the NIF version.
As to the scheduler bits, I'm not sure that I'm really that concerned about it.
AFAIK, its operating under the same principles as term_to_binary, so if the
JSON part is a problem for us, then we should be looking into replacing
term_to_binary with an Erlang version (which we're not so I think we shouldn't
care *too* much). Then again, figuring out a way to test these sorts of things
might be a bonus regardless.
> 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
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