Jens Geyer created THRIFT-6269:
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Summary: Erlang: two avoidable per-byte costs in the socket
transport and the JSON protocol
Key: THRIFT-6269
URL: https://issues.apache.org/jira/browse/THRIFT-6269
Project: Thrift
Issue Type: Improvement
Components: Erlang - Library
Reporter: Jens Geyer
Two spots in {{lib/erl}} do per-byte work where the binding elsewhere works on
binaries whole. Neither is a correctness problem; both are cheap to improve and
they are filed together because they are one class.
h2. 1. {{thrift_socket_transport.erl:71-82}} -- {{loop_recv}} reflattens the
buffer on every pass
{code:erlang}
{ok, Data} ->
Binary = iolist_to_binary([Buf, Data]),
Give = min(iolist_size(Binary), ReadLen),
loop_recv(State#t_socket{buffer = Binary}, ReadLen, ReadLen - Give)
{code}
{{iolist_to_binary/1}} copies everything received so far on each recursion, so
a message arriving in n segments costs O(n^2) bytes copied. Carrying the iolist
forward and flattening once, when the requested length is complete, is the same
shape {{split_binary}} in the base clause already expects.
h2. 2. {{thrift_json_protocol.erl:353-365}} -- {{read_all_1}} reads one byte
per call
{code:erlang}
read_all_1(Transport0, IoList) ->
{Transport1, Result} = thrift_transport:read(Transport0, 1),
{code}
One {{thrift_transport:read/2}} round trip per character of the message. Worth
noting while looking at it: the {{{error, 'EOF'}}} clause below appears to be
unreachable given what {{thrift_transport:read/2}} returns, which suggests the
JSON-over-TCP server path has no test covering it.
h2. Suggested
Take them one at a time; each is self-contained. If the second is picked up,
the apparently dead {{{error, 'EOF'}}} clause is worth resolving in the same
pass -- either by covering that path with a test or by removing the clause.
_Drafted with AI assistance (Claude Opus 5); reviewed and filed by Jens Geyer._
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