Currently some operations of RandomAccessFile are implemented with multiple
read() invocations:
public final int readInt() throws IOException {
int ch1 = this.read();
int ch2 = this.read();
int ch3 = this.read();
int ch4 = this.read();
if ((ch1 | ch2 | ch3 | ch4) < 0)
throw new EOFException();
return ((ch1 << 24) + (ch2 << 16) + (ch3 << 8) + (ch4 << 0));
}
This can be improved by using bulk reads:
public final int readInt() throws IOException {
readFully(readBuffer, 0, 4);
return Bits.getInt(readBuffer, 0);
}
Benchmarking:
baselile
Benchmark (kiloBytes) Mode Cnt Score
Error Units
RandomAccessFileReadBenchmark.readInt 1 avgt 10 1060,526 ±
62,036 us/op
RandomAccessFileReadBenchmark.readInt 5 avgt 10 5745,671 ±
1374,277 us/op
RandomAccessFileReadBenchmark.readLong 1 avgt 10 1399,494 ±
378,072 us/op
RandomAccessFileReadBenchmark.readLong 5 avgt 10 4864,425 ±
329,282 us/op
RandomAccessFileReadBenchmark.readShort 1 avgt 10 1111,163 ±
70,883 us/op
RandomAccessFileReadBenchmark.readShort 5 avgt 10 4933,058 ±
339,273 us/op
patch
Benchmark (kiloBytes) Mode Cnt Score
Error Units
RandomAccessFileReadBenchmark.readInt 1 avgt 10 311,404 ±
17,337 us/op
RandomAccessFileReadBenchmark.readInt 5 avgt 10 1210,381 ±
22,742 us/op
RandomAccessFileReadBenchmark.readLong 1 avgt 10 201,726 ±
8,885 us/op
RandomAccessFileReadBenchmark.readLong 5 avgt 10 667,117 ±
6,779 us/op
RandomAccessFileReadBenchmark.readShort 1 avgt 10 560,259 ±
16,783 us/op
RandomAccessFileReadBenchmark.readShort 5 avgt 10 2251,975 ±
54,533 us/op
-------------
Commit messages:
- 8292937: Fix copyright
- 8292937: Improve performance of some read operations of RandomAccessFile
Changes: https://git.openjdk.org/jdk/pull/10031/files
Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10031&range=00
Issue: https://bugs.openjdk.org/browse/JDK-8292937
Stats: 129 lines in 3 files changed: 96 ins; 22 del; 11 mod
Patch: https://git.openjdk.org/jdk/pull/10031.diff
Fetch: git fetch https://git.openjdk.org/jdk pull/10031/head:pull/10031
PR: https://git.openjdk.org/jdk/pull/10031
