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(*Stream).WriteMore: do not Flush #441
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added 3 commits
January 17, 2020 16:50
Previously it would append to the end of the buffer instead of reusing the
now-free space.
Benchmark demonstrates the improvement, run with -benchtime=10s
benchmark old ns/op new ns/op delta
Benchmark_encode_string_with_SetEscapeHTML-8 447 442 -1.12%
Benchmark_jsoniter_large_file-8 20998 21222 +1.07%
Benchmark_json_large_file-8 39593 40187 +1.50%
Benchmark_stream_encode_big_object-8 10787 8611 -20.17%
benchmark old allocs new allocs delta
Benchmark_encode_string_with_SetEscapeHTML-8 6 6 +0.00%
Benchmark_jsoniter_large_file-8 78 78 +0.00%
Benchmark_json_large_file-8 13 13 +0.00%
Benchmark_stream_encode_big_object-8 31 0 -100.00%
benchmark old bytes new bytes delta
Benchmark_encode_string_with_SetEscapeHTML-8 760 760 +0.00%
Benchmark_jsoniter_large_file-8 4920 4920 +0.00%
Benchmark_json_large_file-8 6640 6640 +0.00%
Benchmark_stream_encode_big_object-8 10056 0 -100.00%
Fixes #438
I believe that WriteMore should not call Flush for these reasons:
1. This is surprising for users because of inconsistency. Why call Flush in
WriteMore and not in WriteObjectEnd?
2. It is not necessary; callers are free to call Flush if their use case demands
it.
3. It harms performance in the common case by flushing the buffer much more
frequently than it needs to be flushed.
The stream benchmark shows a 7% benefit to removing the Flush call, and I
observed a similar speedup in my real-world use case.
benchmark old ns/op new ns/op delta
Benchmark_encode_string_with_SetEscapeHTML-8 442 437 -1.13%
Benchmark_jsoniter_large_file-8 21222 21062 -0.75%
Benchmark_json_large_file-8 40187 40266 +0.20%
Benchmark_stream_encode_big_object-8 8611 7956 -7.61%
benchmark old allocs new allocs delta
Benchmark_encode_string_with_SetEscapeHTML-8 6 6 +0.00%
Benchmark_jsoniter_large_file-8 78 78 +0.00%
Benchmark_json_large_file-8 13 13 +0.00%
Benchmark_stream_encode_big_object-8 0 0 +0.00%
benchmark old bytes new bytes delta
Benchmark_encode_string_with_SetEscapeHTML-8 760 760 +0.00%
Benchmark_jsoniter_large_file-8 4920 4920 +0.00%
Benchmark_json_large_file-8 6640 6640 +0.00%
Benchmark_stream_encode_big_object-8 0 0 +0.00%
Backwards compatibility - I believe there is little to no risk that this breaks
callers. WriteMore does not leave the JSON in a valid state, so it must be
followed by other Write* methods. To get the finished JSON out, the caller must
already be calling Flush.
Codecov Report
@@ Coverage Diff @@
## master #441 +/- ##
==========================================
- Coverage 86.46% 86.38% -0.09%
==========================================
Files 41 41
Lines 5106 5105 -1
==========================================
- Hits 4415 4410 -5
- Misses 555 558 +3
- Partials 136 137 +1
Continue to review full report at Codecov.
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AllenX2018
reviewed
Jan 20, 2020
| func (stream *Stream) WriteMore() { | ||
| stream.writeByte(',') | ||
| stream.writeIndention(0) | ||
| stream.Flush() |
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LGTM, except this line. Not sure what it's here for and if it could be removed. Pls have a check @taowen
AllenX2018
approved these changes
Jan 20, 2020
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@taowen Any thoughts? |
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Ping @taowen |
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zhenzou
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Feb 2, 2022
(*Stream).WriteMore: do not Flush
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I believe that WriteMore should not call Flush for these reasons:
The stream benchmark shows a 7% benefit to removing the Flush call, and I
observed a similar speedup in my real-world use case.
Backwards compatibility - I believe there is little to no risk that this breaks
callers. WriteMore does not leave the JSON in a valid state, so it must be
followed by other Write* methods. To get the finished JSON out, the caller must
already be calling Flush.