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https://issues.apache.org/jira/browse/HBASE-13686?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14543967#comment-14543967
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Guanghao Zhang commented on HBASE-13686:
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1. In my code, now will be updated in every request. This code is just for test
shortly.
2. RateLimiter will be used in TimeBasedLimiter. TimeBasedLimiter will be used
in DefaultOperationQuota. When DefaultOperationQuota.checkQuota(), it will call
TimeBasedLimiter.checkQuota() then call TimeBaseLimiter.grabQuota().
TimeBasedLimiter.checkQuota() will update now and lastTs, then call
RateLimiter.canExecute(). TimeBaseLimiter.grabQuota() will call
RateLimiter.consume() and update lastTs(writeLastTs or ReadLastTs).
my code is just for test the above step shortly.....
> 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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