Compile mochijson2 down to native code
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Key: COUCHDB-798
URL: https://issues.apache.org/jira/browse/COUCHDB-798
Project: CouchDB
Issue Type: Improvement
Components: Database Core
Reporter: Adam Kocoloski
Fix For: 1.1
Adding a -compile(native) flag to mochijson2.erl results in a marked
performance improvement for large documents. I did the following test
node compare_write.js -u http://127.0.0.1:5984 -v http://127.0.0.1:5985 -1
trunk -2 mochijson2-native -d large -r 2 -t 90 -c 200
and got the results at [1]. The graph shows that the average client response
time dropped by about 35% with the native encoder. Qualitatively, I also
noticed that the native encoder used substantially fewer CPU cycles. On my
dual core Macbook, idle CPU went from ~10% on trunk to ~25% with the +native
version while the test was running.
Running the same test with small documents showed essentially no difference
between the two comparatives, which is not surprising.
A potential downside of +native is instability in the VM. I've encountered
issues on AMD machines with R13B04 when using +native for all modules, and the
core dump pointed to an issue in HiPE. On the other hand, I think that
mochijson2 should work very well as native code, since it doesn't do any
message passing or I/O. I'm +1 on simply adding the compile option to the
codebase in trunk to see how it behaves.
[1]:
http://mikeal.couchone.com/graphs/_design/app/_show/compareWriteTest/e69057a29bd6e4ac4ae0115fac00ae50
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