LinkedList info
parent
bdcef85363
commit
5851ea6456
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@ -0,0 +1,30 @@
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--- ../primes.java 2016-09-22 22:10:58.787516331 +0300
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+++ primes.java 2016-09-22 22:11:14.919516331 +0300
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@@ -2,15 +2,15 @@
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import java.lang.Math;
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class PrimeNumbersGenerator {
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- ArrayList<Integer> get_primes7(int n) {
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- ArrayList<Integer> res = new ArrayList<Integer>();
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+ List<Integer> get_primes7(int n) {
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+ List<Integer> res = new LinkedList<Integer>();
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if (n < 2) return res;
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if (n == 2) {
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res.add(2);
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return res;
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}
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- ArrayList<Integer> s = new ArrayList<Integer>();
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+ List<Integer> s = new ArrayList<Integer>();
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for (int i = 3; i < n + 1; i += 2) {
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s.add(i);
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}
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@@ -46,7 +46,7 @@
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long startTime = System.currentTimeMillis();
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long periodTime = Long.parseLong(System.getenv("RUN_TIME"), 10) * 1000;
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- ArrayList<Integer> res;
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+ List<Integer> res;
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while ((System.currentTimeMillis() - startTime) < periodTime) {
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res = (new PrimeNumbersGenerator()).get_primes7(10000000);
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@ -4,5 +4,6 @@ Java can be (a lot) faster than what we see it with its default interpeter setti
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* Initial heap size -- setting this larger than the default value will allow the ArrayList to grow more efficiently by pre-allocating a bigger memory block from the system. The "java" command-line argument is "-Xms500m".
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* Heap and GC tuning -- we can control the ratio between the old and young generations. The "java" command-line argument is "-XX:NewRatio=1".
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* Skip the unneeded boxing/unboxing -- this requires a more native Java implementation. See the source code of "[primes-alt.java](../primes-alt.java)".
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* Use LinkedList -- it has O(1) complexity for adding elements. Benchmark tests however don't show significant improvement under Java 8, and under Java 7 we see a slow down of 59%.
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These tweaks are not included in the Java benchmark test, because I wanted to test the default languages setup. I don't aim to fine-tune any of the implementations by optimizing them for the current task/algorithm. This is a generic test, not an attempt to complete the current task in the fastest possible way for each programming language.
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