proc_maps: Parse address and device without allocating #572
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In our project we need to parse proc maps pretty frequently and we've noticed that there are lots of small allocations coming from parsing the device and addresses from procfs' maps file. The rough split of memory allocated is: - bufio.(*Scanner).Text: 25% - strings.Split: 50% - string.Fields: 25% The two callers of strings.Split are the two parsing functions that we are optimising here. I've added some benchmarks to show the improvements. Before ====== ``` $ go test -benchmem -run=^$ -bench ^BenchmarkParse.*$ github.com/prometheus/procfs goos: linux goarch: amd64 pkg: github.com/prometheus/procfs cpu: Intel(R) Core(TM) i7-8700K CPU @ 3.70GHz BenchmarkParseAddress-12 12218004 123.0 ns/op 32 B/op 1 allocs/op BenchmarkParseDevice-12 15074881 85.11 ns/op 32 B/op 1 allocs/op PASS ok github.com/prometheus/procfs 2.978s ``` After ===== ``` $ go test -benchmem -run=^$ -bench ^BenchmarkParse.*$ github.com/prometheus/procfs goos: linux goarch: amd64 pkg: github.com/prometheus/procfs cpu: Intel(R) Core(TM) i7-8700K CPU @ 3.70GHz BenchmarkParseAddress-12 28619314 50.45 ns/op 0 B/op 0 allocs/op BenchmarkParseDevice-12 49721935 29.66 ns/op 0 B/op 0 allocs/op PASS ok github.com/prometheus/procfs 2.991s ``` Signed-off-by: Francisco Javier Honduvilla Coto <javierhonduco@gmail.com>
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In our project we need to parse proc maps pretty frequently and we've noticed that there are lots of small allocations coming from parsing the device and addresses from procfs' maps file.
The rough split of memory allocated is:
The two callers of strings.Split are the two parsing functions that we are optimising here. I've added some benchmarks to show the improvements.
Before
After