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https://issues.apache.org/jira/browse/THRIFT-401?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12688885#action_12688885
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Bryan Duxbury commented on THRIFT-401:
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If you feel like you have the time and the initiative, then absolutely go
ahead. Otherwise, I'll get around to this... eventually.
> ruby transport class read buffer very slow due to usage of slice!
> -----------------------------------------------------------------
>
> Key: THRIFT-401
> URL: https://issues.apache.org/jira/browse/THRIFT-401
> Project: Thrift
> Issue Type: Improvement
> Components: Library (Ruby)
> Environment: # uname -a
> Linux zvm.local 2.6.9-78.0.1.ELsmp #1 SMP Tue Aug 5 11:02:47 EDT 2008 i686
> i686 i386 GNU/Linux
> Reporter: Tyler Kovacs
> Priority: Minor
> Attachments: after.png, before.png,
> remove_slice_from_framed_transport.diff
>
>
> We use Thrift as a cross-language transport for Hypertable - an open-source
> distributed database. While profiling queries with large response using the
> ruby Thrift libraries, we discovered that the majority of time was spent in
> thrift/transport.rb. Specifically, the slice! method, which is used to
> manage the read buffer (@rbuf) was responsible for almost all latency.
> We tried an alternative implementation that showed 300x speedup in our tests.
> Instead of repeatedly calling slice! to alter @rbuf (which apparently is
> extremely expensive), we maintain an offset counter (@rpos) which starts at
> zero and is incremented by sz each time we read from @rbuf. Before and after
> screenshots from kcachegrind are attached.
> I'll copy the monkey patch that we use within the description below - and
> I'll try to assemble a patch later today.
> module Thrift
> class FramedTransport < Transport
> def initialize(transport, read=true, write=true)
> @transport = transport
> @rbuf = ''
> @wbuf = ''
> @read = read
> @write = write
> @rpos = 0
> end
> def read(sz)
> return @transport.read(sz) unless @read
> return '' if sz <= 0
> read_frame if @rpos >= @rbuf.length
> @rpos += sz
> @rb...@rpos - sz, sz] || ''
> end
> def borrow(requested_length = 0)
> read_frame if @rpos >= @rbuf.length
> # there isn't any more coming, so if it's not enough, it's an error.
> raise EOFError if requested_length > (@rbuf.length - @rpos)
> @rb...@rpos, requested_length]
> end
> def consume!(size)
> @rpos += size
> @rb...@rpos - size, size]
> end
> private
> def read_frame
> sz = @transport.read_all(4).unpack('N').first
> @rpos = 0
> @rbuf = @transport.read_all(sz)
> end
> end
> end
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