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Add a microBenchmark for replacing strings

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It shows that Java 11 improves a lot and no custom string-replace
is necessary any more when using this version
This commit is contained in:
Dominik Stadler 2021-11-07 07:42:38 +01:00
parent 79d1630374
commit f10f164c61
1 changed files with 66 additions and 2 deletions
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68
poi-examples/src/test/java/org/apache/poi/integration/TestXLSX2CSV.java
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@ -33,8 +33,11 @@ import org.apache.poi.openxml4j.opc.PackageAccess;
import org.apache.poi.xssf.XSSFTestDataSamples;
import org.junit.jupiter.api.AfterEach;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Disabled;
import org.junit.jupiter.api.Test;
import net.bytebuddy.utility.RandomString;
public class TestXLSX2CSV {
private PrintStream err;
private final UnsynchronizedByteArrayOutputStream errorBytes = UnsynchronizedByteArrayOutputStream.builder().get();
@ -130,7 +133,68 @@ public class TestXLSX2CSV {
assertEquals("", errorOutput);
String output = outputBytes.toString(StandardCharsets.UTF_8);
assertTrue(output.contains("\"Lorem\",111,,,"), "Had: " + output);
assertTrue(output.contains(",\"hello, xssf\",,\"hello, xssf\","), "Had: " + output);
assertTrue(output.contains("\"Lorem\",111,,,"), "Had: " + output);
assertTrue(output.contains(",\"hello, xssf\",,\"hello, xssf\","), "Had: " + output);
}
@Disabled("Used for local micro-benchmarking")
@Test
public void microBenchmark() {
checkReplace("str");
checkReplace("str.123");
checkReplace("str.123,");
checkReplace("str,,,.123,,,,");
for (int i = 0; i < 1000;i++) {
checkReplace(RandomString.make(20));
}
for (int i = 0;i < 10;i++) {
long start = System.currentTimeMillis();
String str = RandomString.make(100) + "\"\"" + RandomString.make(100) + "\"\"" + RandomString.make(100);
String expected = str.replace("\"", "\"\"");
for (int j = 0;j < 300000;j++) {
//assertEquals(expected, replaceString(str, "\"", "\"\""));
assertEquals(expected, replaceDirect(str, "\"", "\"\""));
}
System.out.println(" , " + (System.currentTimeMillis() - start));
}
// Java 8: replaceString: 1001, 921, 1264, 1019, 1258, 990, 1089, 1430, 1153, 907
// Java 8: replaceDirect: 375, 282, 240, 246, 264, 271, 258, 250, 263, 259
// Java 11: replaceString: 510, 218, 202, 205, 202, 198, 202, 198, 208, 201
// Java 11: replaceDirect: 384, 228, 204, 201, 201, 200, 206, 196, 200, 200
//
// => On Java 8, a custom implementation would make sense, however on Java 9
// String.replace() was optimized so that it does not make any difference
// anymore!
}
private void checkReplace(String orig) {
assertEquals(replaceString(orig, ",", "."), replaceDirect(orig, ",", "."),
"Did have a difference with " + orig);
}
public static String replaceString(String originalStr, String oldStr, String newStr) {
return originalStr.replace(oldStr, newStr);
}
public static String replaceDirect(String originalStr, String oldStr, String newStr) {
int p = originalStr.indexOf(oldStr);
if (p == -1) {
return originalStr;
} else {
StringBuilder result = new StringBuilder();
result.append(originalStr, 0, p);
result.append(newStr);
int q = p + oldStr.length();
while ((p = originalStr.indexOf(oldStr, q)) != -1) {
result.append(originalStr, q, p);
result.append(newStr);
q = p + oldStr.length();
}
result.append(originalStr, q, originalStr.length());
return result.toString();
}
}
}