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https://issues.apache.org/jira/browse/LUCENE-10448?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
kkewwei updated LUCENE-10448:
-----------------------------
Description:
We can see the code in *MergeRateLimiter*:
{code:java}
private long maybePause(long bytes, long curNS) throws
MergePolicy.MergeAbortedException {
double rate = mbPerSec;
double secondsToPause = (bytes / 1024. / 1024.) / rate;
long targetNS = lastNS + (long) (1000000000 * secondsToPause);
long curPauseNS = targetNS - curNS;
// We don't bother with thread pausing if the pause is smaller than 2 msec.
if (curPauseNS <= MIN_PAUSE_NS) {
// Set to curNS, not targetNS, to enforce the instant rate, not
// the "averaged over all history" rate:
lastNS = curNS;
return -1;
}
......
}
{code}
If a Segment is been merged, *maybePause* is called in 7:00, lastNS=7:00, then
the *maybePause* is called in 7:05, so the value of *targetNS=lastNS + (long)
(1000000000 * secondsToPause)* must smaller than *curNS*, so we will return -1.
As long as the interval between two *maybePause* calls is relatively long, the
pause that should be executed will not be executed.
was:
We can see the code:
{code:java}
private long maybePause(long bytes, long curNS) throws
MergePolicy.MergeAbortedException {
double rate = mbPerSec;
double secondsToPause = (bytes / 1024. / 1024.) / rate;
long targetNS = lastNS + (long) (1000000000 * secondsToPause);
long curPauseNS = targetNS - curNS;
// We don't bother with thread pausing if the pause is smaller than 2 msec.
if (curPauseNS <= MIN_PAUSE_NS) {
// Set to curNS, not targetNS, to enforce the instant rate, not
// the "averaged over all history" rate:
lastNS = curNS;
return -1;
}
......
}
{code}
If a Segment is been merged, `maybePause` is called in `7:00`, lastNS=7:00,
then the `maybePause` is called in `7:05`, so the value of `targetNS=lastNS +
(long) (1000000000 * secondsToPause)` must smaller than `curNS`, so we will
return -1. As long as the interval between two `maybePause` calls is relatively
long, the pause that should be executed will not be executed.
> MergeRateLimiter doesn't always limit instant rate.
> ---------------------------------------------------
>
> Key: LUCENE-10448
> URL: https://issues.apache.org/jira/browse/LUCENE-10448
> Project: Lucene - Core
> Issue Type: Bug
> Components: core/other
> Affects Versions: 8.11.1
> Reporter: kkewwei
> Priority: Major
>
> We can see the code in *MergeRateLimiter*:
> {code:java}
> private long maybePause(long bytes, long curNS) throws
> MergePolicy.MergeAbortedException {
>
> double rate = mbPerSec;
> double secondsToPause = (bytes / 1024. / 1024.) / rate;
> long targetNS = lastNS + (long) (1000000000 * secondsToPause);
> long curPauseNS = targetNS - curNS;
> // We don't bother with thread pausing if the pause is smaller than 2
> msec.
> if (curPauseNS <= MIN_PAUSE_NS) {
> // Set to curNS, not targetNS, to enforce the instant rate, not
> // the "averaged over all history" rate:
> lastNS = curNS;
> return -1;
> }
> ......
> }
> {code}
> If a Segment is been merged, *maybePause* is called in 7:00, lastNS=7:00,
> then the *maybePause* is called in 7:05, so the value of *targetNS=lastNS +
> (long) (1000000000 * secondsToPause)* must smaller than *curNS*, so we will
> return -1. As long as the interval between two *maybePause* calls is
> relatively long, the pause that should be executed will not be executed.
>
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