RFR: 8264777: Overload optimized FileInputStream::readAllBytes [v2]
Vladimir Sitnikov
vsitnikov at openjdk.java.net
Wed May 5 06:52:56 UTC 2021
On Tue, 4 May 2021 20:18:25 GMT, Brian Burkhalter <bpb at openjdk.org> wrote:
>> Please consider this request to override the `java.io.InputStream` methods `readAllBytes()` and `readNBytes(int)` in `FileInputStream` with more performant implementations. The method overrides attempt to read all requested bytes into a single array of the required size rather than composing the result from a sequence of smaller arrays. An example of the performance improvements is as follows.
>>
>> **readAllBytes**
>> Before
>>
>> Benchmark (length) Mode Cnt Score Error Units
>> ReadAllBytes.readAllBytesFileInputStream 1000000 thrpt 20 2412.031 ± 7.309 ops/s
>> ReadAllBytes.readAllBytesFileInputStream 10000000 thrpt 20 212.181 ± 0.369 ops/s
>> ReadAllBytes.readAllBytesFileInputStream 100000000 thrpt 20 19.860 ± 0.048 ops/s
>> ReadAllBytes.readAllBytesFileInputStream 1000000000 thrpt 20 1.298 ± 0.183 ops/s
>>
>> After
>>
>> Benchmark (length) Mode Cnt Score Error Units
>> ReadAllBytes.readAllBytesFileInputStream 1000000 thrpt 20 8218.473 ± 43.425 ops/s
>> ReadAllBytes.readAllBytesFileInputStream 10000000 thrpt 20 302.781 ± 1.273 ops/s
>> ReadAllBytes.readAllBytesFileInputStream 100000000 thrpt 20 22.461 ± 0.084 ops/s
>> ReadAllBytes.readAllBytesFileInputStream 1000000000 thrpt 20 1.502 ± 0.003 ops/s
>>
>>
>> **readNBytes**
>>
>> `N = file_size / 2`
>>
>> Before
>>
>> Benchmark (length) Mode Cnt Score Error Units
>> ReadAllBytes.readHalfBytesFileInputStream 1000000 thrpt 20 5585.500 ± 153.353 ops/s
>> ReadAllBytes.readHalfBytesFileInputStream 10000000 thrpt 20 436.164 ± 1.104 ops/s
>> ReadAllBytes.readHalfBytesFileInputStream 100000000 thrpt 20 40.167 ± 0.141 ops/s
>> ReadAllBytes.readHalfBytesFileInputStream 1000000000 thrpt 20 3.291 ± 0.211 ops/s
>>
>>
>> After
>>
>> Benchmark (length) Mode Cnt Score Error Units
>> ReadAllBytes.readHalfBytesFileInputStream 1000000 thrpt 20 15463.210 ± 66.045 ops/s
>> ReadAllBytes.readHalfBytesFileInputStream 10000000 thrpt 20 561.752 ± 0.951 ops/s
>> ReadAllBytes.readHalfBytesFileInputStream 100000000 thrpt 20 45.043 ± 0.102 ops/s
>> ReadAllBytes.readHalfBytesFileInputStream 1000000000 thrpt 20 4.629 ± 0.035 ops/s
>
> Brian Burkhalter has updated the pull request incrementally with one additional commit since the last revision:
>
> 8264777: Handle cases where length() returns zero
src/java.base/share/classes/java/io/FileInputStream.java line 284:
> 282: long size = length - position;
> 283: if (size > (long)Integer.MAX_VALUE)
> 284: throw new OutOfMemoryError("Required array size too large");
What do you think of adding "length, position, and size" to the exception message?
-------------
PR: https://git.openjdk.java.net/jdk/pull/3845
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