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| README.md | H A D | 01-Jun-2020 | 4.8 KiB | 125 | 82 |
README.md
1<!---
2 Licensed to the Apache Software Foundation (ASF) under one
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5 regarding copyright ownership. The ASF licenses this file
6 to you under the Apache License, Version 2.0 (the
7 "License"); you may not use this file except in compliance
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9
10 http://www.apache.org/licenses/LICENSE-2.0
11
12 Unless required by applicable law or agreed to in writing,
13 software distributed under the License is distributed on an
14 "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 KIND, either express or implied. See the License for the
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17 under the License.
18-->
19
20Apache Arrow for Go
21===================
22
23[](https://godoc.org/github.com/apache/arrow/go/arrow)
24
25[Apache Arrow][arrow] is a cross-language development platform for in-memory
26data. It specifies a standardized language-independent columnar memory format
27for flat and hierarchical data, organized for efficient analytic operations on
28modern hardware. It also provides computational libraries and zero-copy
29streaming messaging and inter-process communication.
30
31
32Reference Counting
33------------------
34
35The library makes use of reference counting so that it can track when memory
36buffers are no longer used. This allows Arrow to update resource accounting,
37pool memory such and track overall memory usage as objects are created and
38released. Types expose two methods to deal with this pattern. The `Retain`
39method will increase the reference count by 1 and `Release` method will reduce
40the count by 1. Once the reference count of an object is zero, any associated
41object will be freed. `Retain` and `Release` are safe to call from multiple
42goroutines.
43
44### When to call `Retain` / `Release`?
45
46* If you are passed an object and wish to take ownership of it, you must call
47 `Retain`. You must later pair this with a call to `Release` when you no
48 longer need the object. "Taking ownership" typically means you wish to
49 access the object outside the scope of the current function call.
50
51* You own any object you create via functions whose name begins with `New` or
52 `Copy` or when receiving an object over a channel. Therefore you must call
53 `Release` once you no longer need the object.
54
55* If you send an object over a channel, you must call `Retain` before sending
56 it as the receiver is assumed to own the object and will later call `Release`
57 when it no longer needs the object.
58
59Performance
60-----------
61
62The arrow package makes extensive use of [c2goasm][] to leverage LLVM's
63advanced optimizer and generate PLAN9 assembly functions from C/C++ code. The
64arrow package can be compiled without these optimizations using the `noasm`
65build tag. Alternatively, by configuring an environment variable, it is
66possible to dynamically configure which architecture optimizations are used at
67runtime. See the `cpu` package [README](arrow/internal/cpu/README.md) for a
68description of this environment variable.
69
70### Example Usage
71
72The following benchmarks demonstrate summing an array of 8192 values using
73various optimizations.
74
75Disable no architecture optimizations (thus using AVX2):
76
77```sh
78$ INTEL_DISABLE_EXT=NONE go test -bench=8192 -run=. ./math
79goos: darwin
80goarch: amd64
81pkg: github.com/apache/arrow/go/arrow/math
82BenchmarkFloat64Funcs_Sum_8192-8 2000000 687 ns/op 95375.41 MB/s
83BenchmarkInt64Funcs_Sum_8192-8 2000000 719 ns/op 91061.06 MB/s
84BenchmarkUint64Funcs_Sum_8192-8 2000000 691 ns/op 94797.29 MB/s
85PASS
86ok github.com/apache/arrow/go/arrow/math 6.444s
87```
88
89**NOTE:** `NONE` is simply ignored, thus enabling optimizations for AVX2 and SSE4
90
91----
92
93Disable AVX2 architecture optimizations:
94
95```sh
96$ INTEL_DISABLE_EXT=AVX2 go test -bench=8192 -run=. ./math
97goos: darwin
98goarch: amd64
99pkg: github.com/apache/arrow/go/arrow/math
100BenchmarkFloat64Funcs_Sum_8192-8 1000000 1912 ns/op 34263.63 MB/s
101BenchmarkInt64Funcs_Sum_8192-8 1000000 1392 ns/op 47065.57 MB/s
102BenchmarkUint64Funcs_Sum_8192-8 1000000 1405 ns/op 46636.41 MB/s
103PASS
104ok github.com/apache/arrow/go/arrow/math 4.786s
105```
106
107----
108
109Disable ALL architecture optimizations, thus using pure Go implementation:
110
111```sh
112$ INTEL_DISABLE_EXT=ALL go test -bench=8192 -run=. ./math
113goos: darwin
114goarch: amd64
115pkg: github.com/apache/arrow/go/arrow/math
116BenchmarkFloat64Funcs_Sum_8192-8 200000 10285 ns/op 6371.41 MB/s
117BenchmarkInt64Funcs_Sum_8192-8 500000 3892 ns/op 16837.37 MB/s
118BenchmarkUint64Funcs_Sum_8192-8 500000 3929 ns/op 16680.00 MB/s
119PASS
120ok github.com/apache/arrow/go/arrow/math 6.179s
121```
122
123[arrow]: https://arrow.apache.org
124[c2goasm]: https://github.com/minio/c2goasm
125
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