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https://issues.apache.org/jira/browse/HBASE-13686?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14551834#comment-14551834
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Ashish Singhi commented on HBASE-13686:
---------------------------------------
Thanks [~zghaobac] for reviewing the patch.
bq. if limit and available is Long.MAX_VALUE, when delta > 0, available + delta
will be negative
When can this case occur ? I can think of only one scenario, that is client
executing canExecute for the first time where nextRefillTime will still be
equal to default value i.e., -1 and that case is been already handled by below
code.
{code}
if (refillTime == -1) {
// Till now no resource has been consumed.
this.nextRefillTime.compareAndSet(nextRefillTime.get(),
EnvironmentEdgeManager.currentTime());
return limit;
}
{code}
bq. refill should return the new avail, not the refillAmount
Why you think so ? the new avail value will be calculated based on this
refillAmount in the canExecute which I thought is ok.
> 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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