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https://issues.apache.org/jira/browse/HBASE-13686?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14544883#comment-14544883
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Guanghao Zhang commented on HBASE-13686:
----------------------------------------
This is a new TestCase in TestRateLimiter.
{code}
@Test
public void testLimiterBySmallerRate() throws InterruptedException {
RateLimiter limiter = new RateLimiter();
// set limiter is 10 resources per seconds
limiter.set(10, TimeUnit.SECONDS);
long lastTs = System.currentTimeMillis();
int count = 0; // control the test count
while ( (count++) < 100) {
// test will get 3 resources per 0.5 sec. so it will get 6 resources per
sec.
Thread.sleep(500);
for (int i = 0; i < 3; i++) {
long nowTs = System.currentTimeMillis();
// 6 resources/sec < limit, so limiter.canExecute(nowTs, lastTs) should
be true
assertEquals(true, limiter.canExecute(nowTs, lastTs));
limiter.consume();
lastTs = nowTs;
}
}
}
{code}
> Fail to limit rate in RateLimiter
> ---------------------------------
>
> Key: HBASE-13686
> URL: https://issues.apache.org/jira/browse/HBASE-13686
> Project: HBase
> Issue Type: Bug
> Affects Versions: 2.0.0, 1.1.0
> Reporter: Guanghao Zhang
> Priority: Minor
>
> While using the patch in HBASE-11598 , I found that RateLimiter can't to
> limit the rate right.
> {code}
> /**
> * given the time interval, are there enough available resources to allow
> execution?
> * @param now the current timestamp
> * @param lastTs the timestamp of the last update
> * @param amount the number of required resources
> * @return true if there are enough available resources, otherwise false
> */
> public synchronized boolean canExecute(final long now, final long lastTs,
> final long amount) {
> return avail >= amount ? true : refill(now, lastTs) >= amount;
> }
> {code}
> When avail >= amount, avail can't be refill. But in the next time to call
> canExecute, lastTs maybe update. So avail will waste some time to refill.
> Even we use smaller rate than the limit, the canExecute will return false.
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