I have a Java program (compiled using JDK 7u80) which makes extensive use of the "JavaScript" ScriptEngine (JSR-223). I have noticed that my program runs extremely slow when executed under a Java 8 runtime environment (JRE 8u65) in comparison to a Java 7 runtime environment (JRE 7u80).
I have put together the following SSCCE to demonstrate the problem and then executed it under Java 7 and Java 8 on the same Windows PC:
import javax.script.*;
public class SSCCE {
public SSCCE() {
ScriptEngineManager sem = new ScriptEngineManager();
ScriptEngine js = sem.getEngineByName("JavaScript");
long t = 0;
int i = 0;
String gJs = "function ip2long(ip) {";
gJs += "var aIP = ip.split(\".\");";
gJs += "return (aIP[0] * Math.pow(256, 3)) + (aIP[1] * Math.pow(256, 2)) + (aIP[2] * 256) + (aIP[3] * 1);";
gJs += "}";
gJs += "function long2ip(l) {";
gJs += "if (!isNaN(l) && ((l >= 0) || (l <= Math.pow(2, 32)))) {";
gJs += "return Math.floor(l / Math.pow(256, 3)) + \".\" +";
gJs += "Math.floor((l % Math.pow(256, 3)) / Math.pow(256, 2)) + \".\" +";
gJs += "Math.floor(((l % Math.pow(256, 3)) % Math.pow(256, 2)) / Math.pow(256, 1)) + \".\" +";
gJs += "Math.floor((((l % Math.pow(256, 3)) % Math.pow(256, 2)) % Math.pow(256, 1)) / Math.pow(256, 0));";
gJs += "}";
gJs += "return null;";
gJs += "}";
try {
js.eval(gJs);
}
catch (Exception e) {
e.printStackTrace();
}
System.out.println("Warming Up...");
t = System.nanoTime();
for (i = 0; i < 4097; i++) {
try {
String sJs = "var ip = \"192.0.2.0\";";
sJs += "var nip = long2ip(ip2long(ip, " + i + "));";
js.eval(sJs);
}
catch (Exception e) {
e.printStackTrace();
}
}
System.out.println("Starting...");
t = System.nanoTime();
for (i = 0; i < 4097; i++) {
try {
String sJs = "var ip = \"192.0.2.0\";";
sJs += "var nip = long2ip(ip2long(ip, " + i + "));";
js.eval(sJs);
}
catch (Exception e) {
e.printStackTrace();
}
}
System.out.println("Elapsed Time: " + (System.nanoTime() - t) / 1000000000.0f);
}
public static void main(String[] args) {
new SSCCE();
}
}
The JavaScript consists of a function which converts an IP address to a long, adds a number and then converts it to back an IP address - this is repeated 4096 times.
I am seeing the following results between Java 7 and Java 8:
D:\Scripts>java7 SSCCE
Warming Up...
Starting...
Elapsed Time: 0.5856594
D:\Scripts>java8 SSCCE
Warming Up...
Starting...
Elapsed Time: 4.6862915
Should I be raising this as a performance bug associated with Java 8?
UPDATED: To include a warm up phase to ensure all code paths have been initialized before my timing loop.