[
https://issues.apache.org/jira/browse/HBASE-18470?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16110091#comment-16110091
]
Benedict Jin commented on HBASE-18470:
--------------------------------------
Hi, [~tedyu]. Thank you for comment. Sure, skipping add comma is a good
solution and i tried it in the beginning. But i changed my mind after some
performance tests that seems `substring` solution is always faster than
`skipping add comma`. Details is here:
```java
/*
JVM: -ea -Xmx512M -Xms512M -Xmn128M -XX:+AlwaysPreTouch
Time: 0.023948 ms
Time: 0.012752 ms
*/
@Test
public void testStringBuilder() {
Set<String> uniqAddr = new HashSet<>();
StringBuilder addrs = new StringBuilder();
long begin, performanceTime;
{
uniqAddr.add("a");
uniqAddr.add("b");
uniqAddr.add("c");
begin = System.nanoTime();
int count = 0, addrLen = uniqAddr.size();
for (String addr : uniqAddr) {
addrs.append(addr);
count++;
if (count != addrLen) {
addrs.append(", ");
}
}
String withoutTail = addrs.toString();
performanceTime = System.nanoTime() - begin;
_log.info("Time: {} ms", performanceTime * Math.pow(10, -6));
assertEquals("a, b, c", withoutTail);
}
{
addrs = new StringBuilder();
uniqAddr.clear();
uniqAddr.add("a");
uniqAddr.add("b");
uniqAddr.add("c");
begin = System.nanoTime();
for (String addr : uniqAddr) {
addrs.append(addr).append(", ");
}
String withoutTail = uniqAddr.size() > 0 ? addrs.substring(0,
addrs.length() - 2) : addrs.toString();
performanceTime = System.nanoTime() - begin;
_log.info("Time: {} ms", performanceTime * Math.pow(10, -6));
assertEquals("a, b, c", withoutTail);
assertEquals("a, b, c", uniqAddr.size() > 0 ?
addrs.delete(addrs.length() - 2, addrs.length()).toString() :
addrs.toString());
}
}
```
(Full code:
https://github.com/asdf2014/yuzhouwan/blob/master/yuzhouwan-hacker/src/test/java/com/yuzhouwan/hacker/algorithms/collection/StringTest.java#L38)
> `RetriesExhaustedWithDetailsException#getDesc` describe is not right
> --------------------------------------------------------------------
>
> Key: HBASE-18470
> URL: https://issues.apache.org/jira/browse/HBASE-18470
> Project: HBase
> Issue Type: Bug
> Components: Client
> Reporter: Benedict Jin
> Assignee: Benedict Jin
> Attachments: HBASE-18470.master.001.patch
>
> Original Estimate: 72h
> Remaining Estimate: 72h
>
> The describe from `RetriesExhaustedWithDetailsException#getDesc` is `
> org.apache.hadoop.hbase.client.RetriesExhaustedWithDetailsException: Failed 3
> actions: FailedServerException: 3 times, `, there is a not need ', ' in the
> tail.
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