Change MaxJavaStackTraceDepth JVM flag in runtime

ChangeVMFlag.java

import sun.jvm.hotspot.debugger.Address;
import sun.jvm.hotspot.runtime.VM;
import sun.jvm.hotspot.tools.Tool;

import java.io.IOException;
import java.io.RandomAccessFile;

/**
 * Changes -XX:MaxJavaStackTraceDepth flag to 1000000 in runtime
 * without restarting the JVM.
 * See https://stackoverflow.com/q/65239783/3448419
 *
 * How to run on JDK 8:
 * java -cp .:$JAVA_HOME/lib/sa-jdi.jar ChangeVMFlag <pid>
 *
 * On Java 9+:
 * java --add-modules=jdk.hotspot.agent \
 *      --add-exports jdk.hotspot.agent/sun.jvm.hotspot.tools=ALL-UNNAMED \
 *      --add-exports jdk.hotspot.agent/sun.jvm.hotspot.runtime=ALL-UNNAMED \
 *      --add-exports jdk.hotspot.agent/sun.jvm.hotspot.debugger=ALL-UNNAMED \
 *      ChangeVMFlag <pid>
 */
public class ChangeVMFlag extends Tool {
    private static String pid;

    @Override
    public void run() {
        Address addr = VM.getVM().getCommandLineFlag("MaxJavaStackTraceDepth").getAddress();
        long addrValue = VM.getVM().getDebugger().getAddressValue(addr);

        try (RandomAccessFile raf = new RandomAccessFile("/proc/" + pid + "/mem", "rw")) {
            raf.seek(addrValue);
            raf.writeInt(Integer.reverseBytes(1_000_000));
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        pid = args[0];
        new ChangeVMFlag().execute(new String[]{pid});
    }
}