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https://issues.apache.org/jira/browse/HBASE-13686?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14551764#comment-14551764
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Guanghao Zhang commented on HBASE-13686:
----------------------------------------
[~ashish singhi] Thanks for your patch.
{code}
long delta = (limit * (now - refillTime)) / intervalInMillis;
if (delta > 0) {
return nextRefillTime.compareAndSet(refillTime, now) ? Math.min(limit,
available + delta) : 0;
}
{code}
if limit and available is Long.MAX_VALUE, when delta > 0, available + delta
will be negative. The return value will be negative. Although "check positive
overflow" can catch this case.
In my opinion, move "check positive overflow" in refill method maybe better.
And the refill should return the new avail, not the refillAmount.
Welcome to discuss about that.
> 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
> Assignee: Ashish Singhi
> Fix For: 2.0.0, 1.2.0, 1.1.1
>
> Attachments: HBASE-13686.patch
>
>
> 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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