After I had installed both jdk (open and oracle's), I started wondering what is the difference between them, when it comes to performance. Recently I found some time in the evening and wrote simple tests, which are not very accurate, but give the general notion about performance.
Let's take a look into tests:
ArrayListAppendTest
List<Long> list = new ArrayList<Long>();
for (long l = 0; l <1000000; l++) {
list.add(l);
}
ArrayListInsertMiddleTest
List<Long> list = new ArrayList<Long>();
for (long l = 0; l < 1000; l++) {
list.add(l);
}
for (long l = 0; l < 10000; l++) {
list.add(500, l);
}
ArrayListSortTest
Listlist = new ArrayList (); for (int i = 100000; i > 0; i--) { String str = String.format("String nr %5s", i); list.add(str); } Collections.sort(list);
LinkedListAppendTest, LinkedListInsertMiddleTest, LinkedListSortTest are exactly the same as for ArrayList, but with subtle change...
DoubleAddTest
double val = 0.0;
for (int i = 0; i< 1000000; i++) {
val += (double) i;
}
SinusTest
for(int i = 0; i < 1000000; i++) {
double val = Math.sin((double) i);
}
StringAppendTest
String [] strings = new String[1000];
for (int i = 0; i < strings.length; i++) {
strings[i] = String.format("Str %d", i);
}
String concat = "";
for (int i = 0; i < strings.length; i++) {
concat += strings[i];
}
All tests *ISTest use various input streams, *OSTest - output streams.
When it comes to reflection tests, I tried to instantiate class using classe's newInstance method, in case of CallMethod test I'm calling one argument method using reflection. Simple...
For comparison I executed test on my ancient computer (Amd64 3500+). After that I compiled and run tests on Raspberry Pi using proper JDK.
And the resulst are... interesting (execution time is in ms):
| Test name | JDK Oracle 1.7 @ AMD64 3500 | Oracle JDK 1.8 ea @ RPi | Open JDK 1.7 @ RPi | Ratio |
|---|---|---|---|---|
| ArrayListAppendTest | 348,6 | 2632 | 10965,1 | 4,2 |
| ArrayListInsertMiddleTest | 72,6 | 285,7 | 1024,7 | 3,6 |
| ArrayListSortTest | 19,6 | 292,9 | 2394,4 | 8,2 |
| BufferedFileOS | 12,2 | 45,4 | 856,4 | 18,9 |
| DoubleAddTest | 0,2 | 35,8 | 390,5 | 10,9 |
| FileISTest | 25,3 | 183,8 | 231,5 | 1,3 |
| FileOSTest | 96,8 | 524,9 | 1618,9 | 3,1 |
| LinkedListAppendTest | 636,1 | 3393,7 | 16634,3 | 4,9 |
| LinkedListInsertMiddleTest | 23,3 | 99,5 | 2159 | 21,7 |
| LinkedListSortTest | 44,8 | 270,9 | 2225,9 | 8,2 |
| ReflectionCallMethodTest | 116,3 | 803,2 | 3496,7 | 4,4 |
| ReflectionNewInstanceTest | 55,5 | 202,5 | 542,4 | 2,7 |
| SinusTest | 268,6 | 562,5 | 3722 | 6,6 |
| StringAppendTest | 49,3 | 254,4 | 489,1 | 1,9 |
As you can see Open JDK in those test is far behind oracle's (in column Ratio you can see, how much slower Open JDK was :/).
I think I stick to JDK 1.8 ea...
