Java – search the code base for large methods

By default, hotspot JIT refuses to compile methods larger than 8K bytecode (1) Is there any way to scan cans (2)?

>Unless you pass - XX: - dontcompilehugemethods > Jon Masamitsu describes explaining how methods slow down garbage collection and points out that refactoring is usually smarter than - XX: - dontcompilehugemethods

Solution

Thank Peter Lawley for pointing to ASM This program prints out the size of each method in the jar:

import org.objectweb.asm.ClassReader;
import org.objectweb.asm.tree.ClassNode;
import org.objectweb.asm.tree.MethodNode;

public static void main(String[] args) throws IOException {
    for (String filename : args) {
        System.out.println("Methods in " + filename);
        ZipFile zip = new ZipFile(filename);
        Enumeration<? extends ZipEntry> it = zip.entries();
        while (it.hasMoreElements()) {
            InputStream clazz = zip.getInputStream(it.nextElement());
            try {
                ClassReader cr = new ClassReader(clazz);
                ClassNode cn = new ClassNode();
                cr.accept(cn,ClassReader.SKIP_DEBUG);
                List<MethodNode> methods = cn.methods;
                for (MethodNode method : methods) {
                    int count = method.instructions.size();
                    System.out.println(count + " " + cn.name + "." + method.name);
                }
            } catch (IllegalArgumentException ignored) {
            }
        }
    }
}