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40% ForestDB performance regression on iOS #1378

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snej opened this issue Jul 21, 2016 · 2 comments
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40% ForestDB performance regression on iOS #1378

snej opened this issue Jul 21, 2016 · 2 comments
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chore performance
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1.3

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snej commented Jul 21, 2016

I ran my unofficial "iTunesLibrary" benchmark on my iPhone 6 yesterday, and performance with ForestDB is 40% slower than 1.2.1. SQLite is unchanged.

Using Instruments I tracked this down to a recent ForestDB change that replaces two large (64kbyte) stack-based buffers with malloced ones. Large malloc calls (>32kb) on Darwin go directly to the vm_allocate system call, which is a lot slower than for small allocations. Backing out this change fixed the performance regression.
@snej snej added this to the 1.3 milestone Jul 21, 2016
@snej snej self-assigned this Jul 21, 2016
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snej commented Jul 21, 2016

This was filed against ForestDB as MB-20219. They're fixing it by rolling back the change.

snej added a commit to couchbaselabs/cbforest that referenced this issue Jul 21, 2016
@snej
Updated ForestDB to fix iOS performance regression
26e5c3d 
Picked up rollback that resolves MB-20219.
For couchbase/couchbase-lite-ios#1378
@snej snej closed this as completed in 41e2dd6 Jul 21, 2016
@snej snej added the chore label Aug 2, 2016
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snej commented Aug 2, 2016

I've tagged this with "chore" so it won't show up in release notes. (We should have a "regression" tag for this purpose...)

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