Bryan Beaudreault created HBASE-28359:
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Summary: Improve quota RateLimiter synchronization
Key: HBASE-28359
URL: https://issues.apache.org/jira/browse/HBASE-28359
Project: HBase
Issue Type: Improvement
Reporter: Bryan Beaudreault
We've been experiencing RpcThrottlingException with 0ms waitInterval. This
seems odd and wasteful, since the client side will immediately retry without
backoff. I think the problem is related to the synchronization of RateLimiter.
The TimeBasedLimiter checkQuota method does the following:
{code:java}
if (!reqSizeLimiter.canExecute(estimateWriteSize + estimateReadSize)) {
RpcThrottlingException.throwRequestSizeExceeded(
reqSizeLimiter.waitInterval(estimateWriteSize + estimateReadSize));
} {code}
Both canExecute and waitInterval are synchronized, but we're calling them
independently. So it's possible under high concurrency for canExecute to return
false, but then waitInterval returns 0 (would have been true)
I think we should simplify the API to have a single synchronized call:
{code:java}
long waitInterval = reqSizeLimiter.tryAcquire(estimateWriteSize +
estimateReadSize);
if (waitInterval > 0) {
RpcThrottlingException.throwRequestSizeExceeded(waitInterval);
}{code}
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