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From "Ashish Singhi (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HBASE-13686) Fail to limit rate in RateLimiter
Date Mon, 08 Jun 2015 09:20:01 GMT

     [ https://issues.apache.org/jira/browse/HBASE-13686?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Ashish Singhi updated HBASE-13686:
----------------------------------
    Release Note: 
As per this jira contribution. We now support two kinds of RateLimiter.
1) org.apache.hadoop.hbase.quotas.AverageIntervalRateLimiter : This limiter will refill resources
at every TimeUnit/resources interval.
Example: For a limiter configured with 10resources/second, then 1resource will be refilled
after every 100ms.

2) org.apache.hadoop.hbase.quotas.FixedIntervalRateLimiter: This limiter will refill resources
only after a given fixed interval of time.

Client can configure anyone of this rate limiter for the cluster by setting the value for
the property "hbase.quota.rate.limiter" in the hbase-site.xml. org.apache.hadoop.hbase.quotas.AverageIntervalRateLimiter
is the default value.
Note: Client needs to restart the cluster for the configuration to take into effect.

> 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
>              Labels: multitenancy, quota
>             Fix For: 2.0.0, 1.2.0, 1.1.1
>
>         Attachments: HBASE-13686-branch-1.patch, HBASE-13686-v1.patch, HBASE-13686-v2.patch,
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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