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https://issues.apache.org/jira/browse/HBASE-13888?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14584613#comment-14584613
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Ashish Singhi commented on HBASE-13888:
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bq. when quota set is bigger than 35, the quota will not work. As I output the
log and found that after 30 ms, client have 15 request, then avail will be 35 -
15 = 20. then the refill will return Math.min(35, 20 + 1), because delta > 0.
refillAmount is 21, then avail = Math.max(0, Math.min(avail + refillAmount,
limit)); so avail will be 35, again. Every 30 ms, this is a cycle, so the
limiter can not work.
Ok I got it. Left couple of comments on the RB.
> refill bug from HBASE-13686
> ---------------------------
>
> Key: HBASE-13888
> URL: https://issues.apache.org/jira/browse/HBASE-13888
> Project: HBase
> Issue Type: Bug
> Affects Versions: 2.0.0
> Reporter: Guanghao Zhang
> Assignee: Guanghao Zhang
> Attachments: HBASE-13888-v1.patch, HBASE-13888-v2.patch
>
>
> As I report the RateLimiter fail to limit in HBASE-13686, then [~ashish
> singhi] fix that problem by support two kinds of RateLimiter:
> AverageIntervalRateLimiter and FixedIntervalRateLimiter. But in my use of the
> code, I found a new bug about refill() in AverageIntervalRateLimiter.
> {code}
> long delta = (limit * (now - nextRefillTime)) /
> super.getTimeUnitInMillis();
> if (delta > 0) {
> this.nextRefillTime = now;
> return Math.min(limit, available + delta);
> }
> {code}
> When delta > 0, refill maybe return available + delta. Then in the
> canExecute(), avail will add refillAmount again. So the new avail maybe 2 *
> avail + delta.
> {code}
> long refillAmount = refill(limit, avail);
> if (refillAmount == 0 && avail < amount) {
> return false;
> }
> // check for positive overflow
> if (avail <= Long.MAX_VALUE - refillAmount) {
> avail = Math.max(0, Math.min(avail + refillAmount, limit));
> } else {
> avail = Math.max(0, limit);
> }
> {code}
> I will add more unit tests for RateLimiter in the next days.
> Review Board: https://reviews.apache.org/r/35384/
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