Fix RAM usage estimation of LiveVersionMap. #20123
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Fortunately this bug was never released, it is 5.0-only. |
| @@ -146,7 +157,7 @@ VersionValue getUnderLock(final Term uid) { | |||
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| /** Adds this uid/version to the pending adds map. */ | |||
| void putUnderLock(BytesRef uid, VersionValue version) { | |||
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| assert uid.bytes.length == uid.length; // otherwise we are wasting memory | |||
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maybe put the actual and expected length in the message
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left a minor LGTM otherwise - good catch :) |
I was writing tests for RAM usage estimation of LiveVersionMap and found a couple issues: - The BytesRef objects used as uids were oversized since they were created via `new BytesRef(CharSequence)` which creates a `byte[]` whose size is 3x the length of the provided char sequence. Given that our uids are most of times ASCII sequences, this is a waste of memory. - `VersionValue` was using `translogLocation.size` instead of `translogLocation.ramBytesUsed()` for RAM estimation, which is completely unrelated to the memory footprint of the `Translog.Location` object. In particular, the latter issue could cause RAM usage estimation to be significantly overestimated, especially on large documents. I also added tests for ram accounting.
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I was writing tests for RAM usage estimation of LiveVersionMap and found a
couple issues:
via
new BytesRef(CharSequence)which creates abyte[]whose size is 3xthe length of the provided char sequence. Given that our uids are most of
times ASCII sequences, this is a waste of memory.
VersionValuewas usingtranslogLocation.sizeinstead oftranslogLocation.ramBytesUsed()for RAM estimation, which is completelyunrelated to the memory footprint of the
Translog.Locationobject.In particular, the latter issue could cause RAM usage estimation to be
significantly overestimated, especially on large documents.
I also added tests for ram accounting.
Relates #19787