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Josh Cummings suggestions: JMH documentation states that benchmark methods should return a value in order to defend against Dead Code Elimination

This commit is contained in:
Fabio Silva 2019-12-19 07:28:51 -03:00
parent 2d6be72eab
commit 9c512c4a82
1 changed files with 11 additions and 10 deletions
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21
core-java-modules/core-java-text/src/main/java/com/baeldung/patternreuse/PatternPerformanceComparison.java
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@ -1,6 +1,7 @@
package com.baeldung.patternreuse; package com.baeldung.patternreuse;
import org.openjdk.jmh.annotations.*; import org.openjdk.jmh.annotations.*;
import org.openjdk.jmh.infra.Blackhole;
import org.openjdk.jmh.runner.RunnerException; import org.openjdk.jmh.runner.RunnerException;
import java.io.IOException; import java.io.IOException;
@ -29,52 +30,52 @@ public class PatternPerformanceComparison {
} }
@Benchmark @Benchmark
public void matcherFromPreCompiledPatternResetMatches() { public void matcherFromPreCompiledPatternResetMatches(Blackhole bh) {
//With pre-compiled pattern and reusing the matcher //With pre-compiled pattern and reusing the matcher
// 1 Pattern object created // 1 Pattern object created
// 1 Matcher objects created // 1 Matcher objects created
for (String value : values) { for (String value : values) {
matcherFromPreCompiledPattern.reset(value).matches(); bh.consume(matcherFromPreCompiledPattern.reset(value).matches());
} }
} }
@Benchmark @Benchmark
public void preCompiledPatternMatcherMatches() { public void preCompiledPatternMatcherMatches(Blackhole bh) {
// With pre-compiled pattern // With pre-compiled pattern
// 1 Pattern object created // 1 Pattern object created
// 5_000_000 Matcher objects created // 5_000_000 Matcher objects created
for (String value : values) { for (String value : values) {
preCompiledPattern.matcher(value).matches(); bh.consume(preCompiledPattern.matcher(value).matches());
} }
} }
@Benchmark @Benchmark
public void patternCompileMatcherMatches() { public void patternCompileMatcherMatches(Blackhole bh) {
// Above approach "Pattern.matches(PATTERN, value)" makes this internally // Above approach "Pattern.matches(PATTERN, value)" makes this internally
// 5_000_000 Pattern objects created // 5_000_000 Pattern objects created
// 5_000_000 Matcher objects created // 5_000_000 Matcher objects created
for (String value : values) { for (String value : values) {
Pattern.compile(PATTERN).matcher(value).matches(); bh.consume(Pattern.compile(PATTERN).matcher(value).matches());
} }
} }
@Benchmark @Benchmark
public void patternMatches() { public void patternMatches(Blackhole bh) {
// Above approach "value.matches(PATTERN)" makes this internally // Above approach "value.matches(PATTERN)" makes this internally
// 5_000_000 Pattern objects created // 5_000_000 Pattern objects created
// 5_000_000 Matcher objects created // 5_000_000 Matcher objects created
for (String value : values) { for (String value : values) {
Pattern.matches(PATTERN, value); bh.consume(Pattern.matches(PATTERN, value));
} }
} }
@Benchmark @Benchmark
public void stringMatchs() { public void stringMatchs(Blackhole bh) {
// 5_000_000 Pattern objects created // 5_000_000 Pattern objects created
// 5_000_000 Matcher objects created // 5_000_000 Matcher objects created
Instant start = Instant.now(); Instant start = Instant.now();
for (String value : values) { for (String value : values) {
value.matches(PATTERN); bh.consume(value.matches(PATTERN));
} }
} }