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Posted to dev@zookeeper.apache.org by asdf2014 <gi...@git.apache.org> on 2017/06/22 11:34:08 UTC
[GitHub] zookeeper pull request #290: Using `Collections.singletonList` instead of `A...
GitHub user asdf2014 opened a pull request:
https://github.com/apache/zookeeper/pull/290
Using `Collections.singletonList` instead of `Arrays.asList(oneElement)`
Using `Collections.singletonList` instead of `Arrays.asList(oneElement)` for reusing a immutable object instead of creating a new object.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/asdf2014/zookeeper coll_stuff
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/zookeeper/pull/290.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #290
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[GitHub] zookeeper issue #290: ZOOKEEPER-2817: Using `Collections.singletonList` inst...
Posted by asdf2014 <gi...@git.apache.org>.
Github user asdf2014 commented on the issue:
https://github.com/apache/zookeeper/pull/290
Hi, @afine. Thank you for code review. It maybe due to...
```java
// -ea -Xmx512M -Xms512M -Xmn256M -XX:+AlwaysPreTouch
@Test
public void testSingletonListPerformance() {
String site = "yuzhouwan.com";
int count = 1_0000_0000;
long spendTime = 0;
while (count > 0) {
long startTime = System.nanoTime();
Collections.singleton(site);
long endTime = System.nanoTime();
count--;
spendTime += endTime - startTime;
}
Runtime runtime = Runtime.getRuntime();
long totalMemory = runtime.totalMemory() / 1024 / 1024;
long freeMemory = runtime.freeMemory() / 1024 / 1024;
// [Collections.singleton] Spend Time: 1370786852ns = 1370.786852ms, Mem: 39/441/480 MB (diff/free/total)
_log.info("[Collections.singleton] Spend Time: {}ns = {}ms, Mem: {}/{}/{} MB (diff/free/total)",
spendTime, spendTime / Math.pow(10, 6), totalMemory - freeMemory, freeMemory, totalMemory);
}
// -ea -Xmx512M -Xms512M -Xmn256M -XX:+AlwaysPreTouch
@Test
public void testArraysAsListPerformance() {
String site = "yuzhouwan.com";
int count = 1_0000_0000;
long spendTime = 0;
while (count > 0) {
long startTime = System.nanoTime();
Arrays.asList(site);
long endTime = System.nanoTime();
count--;
spendTime += endTime - startTime;
}
Runtime runtime = Runtime.getRuntime();
long totalMemory = runtime.totalMemory() / 1024 / 1024;
long freeMemory = runtime.freeMemory() / 1024 / 1024;
// [Arrays.asList] Spend Time: 1549508768ns = 1549.508768ms, Mem: 195/312/507 MB (diff/free/total)
_log.info("[Arrays.asList] Spend Time: {}ns = {}ms, Mem: {}/{}/{} MB (diff/free/total)",
spendTime, spendTime / Math.pow(10, 6), totalMemory - freeMemory, freeMemory, totalMemory);
}
```
Full code is [here](https://github.com/asdf2014/yuzhouwan/blob/master/yuzhouwan-hacker/src/test/java/com/yuzhouwan/hacker/algorithms/collection/CollectionStuffTest.java#L168).
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