On Thu, 8 Aug 2024 11:43:07 GMT, Shaojin Wen <[email protected]> wrote:
>> This PR implements the same algorithm as the current generateMHInlineCopy
>> based on bytecode to improve startup performance.
>
> Shaojin Wen has updated the pull request incrementally with one additional
> commit since the last revision:
>
> fix comments
I have reviewed the code several times and fixed anything I thought could be
improved.
I didn't find a way to test class unloading. For example, I dynamically loaded
a method with string concatenation from byte[] code, and then allocated a very
large array to trigger OutOfMemoryError, but the class of
InlineHiddenClassStrategy.CACHE was still not removed.
Below is my test code:
* Concat Class
Compile the following code into a class and rename it to .clazz as a resource
file
public class Concat {
public static String concat(String a, String b, int i, long j) {
return a + b + i + j;
}
}
* TestClass
import org.apache.commons.io.FileUtils;
import java.io.File;
import java.lang.reflect.Method;
import java.net.URL;
public class ClassLoadingTest {
public static void main(String[] args) throws Throwable {
for (int i = 0; i < 10_000_000; i++) {
perf(i);
}
}
public static void perf(int i) throws Throwable {
URL resource =
ClassLoadingTest.class.getClassLoader().getResource("Concat.clazz");
byte[] code = FileUtils.readFileToByteArray(new
File(resource.getFile()));
MyClassLoader classLoader = new MyClassLoader();
Class<?> concatClass = classLoader.defineClass("Concat", code);
Method concat = concatClass.getMethod("concat", String.class,
String.class, int.class, long.class);
Object result = concat.invoke(null, "abc", "d", i, 0L);
gc();
if (i % 1000 == 0) {
System.out.println(result);
}
}
public static void gc() {
try {
long[] array = new long[Integer.MAX_VALUE];
System.out.println(array.length);
System.gc();
} catch (OutOfMemoryError ignored) {
// skip
}
}
static class MyClassLoader extends ClassLoader {
public Class<?> defineClass(String name, byte[] b) {
return defineClass(name, b, 0, b.length);
}
}
}
* Script to check for class unloading
jps | grep ClassLoadingTest
jmap -histo <pid> | grep StringConcat
-------------
PR Comment: https://git.openjdk.org/jdk/pull/20273#issuecomment-2277042311
