mikemccand commented on code in PR #12604:
URL: https://github.com/apache/lucene/pull/12604#discussion_r1344628522
##########
lucene/CHANGES.txt:
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@@ -163,6 +163,9 @@ Optimizations
* GITHUB#12382: Faster top-level conjunctions on term queries when sorting by
descending score. (Adrien Grand)
+* GITHUB#12604: Estimate the block size of FST BytesStore in
BlockTreeTermsWriter
+ to reducing GC load during indexing. (Guo Feng)
Review Comment:
reducing -> reduce
##########
lucene/core/src/java/org/apache/lucene/codecs/lucene90/blocktree/Lucene90BlockTreeTermsWriter.java:
##########
@@ -490,10 +491,22 @@ public void compileIndex(
}
}
+ long estimateSize = prefix.length;
Review Comment:
Too bad we don't have a writer that uses tiny (like 8 bytes) block at first,
but doubles size for each new block (16 bytes, 32 bytes next, etc.). Then we
would naturally use log(size) number of blocks without over-allocating.
But then reading bytes is a bit tricky because we'd need to take discrete
log (base 2) of the address. Maybe it wouldn't be so bad -- we could do this
with `Long.numberOfLeadingZeros` maybe? But that's a bigger change ... we can
do this separately/later.
##########
lucene/core/src/java/org/apache/lucene/codecs/lucene90/blocktree/Lucene90BlockTreeTermsWriter.java:
##########
@@ -490,10 +491,22 @@ public void compileIndex(
}
}
+ long estimateSize = prefix.length;
+ for (PendingBlock block : blocks) {
+ if (block.subIndices != null) {
Review Comment:
We also should really explore the `TODO` above to write `vLong` in opposite
byte order -- this might save quite a bit of storage in the FST since outputs
would share more prefixes. Again, separate issue 😀
##########
lucene/core/src/java/org/apache/lucene/codecs/lucene90/blocktree/Lucene90BlockTreeTermsWriter.java:
##########
@@ -490,10 +491,22 @@ public void compileIndex(
}
}
+ long estimateSize = prefix.length;
+ for (PendingBlock block : blocks) {
+ if (block.subIndices != null) {
Review Comment:
We also should really explore the `TODO` above to write `vLong` in opposite
byte order -- this might save quite a bit of storage in the FST since outputs
would share more prefixes. Again, separate issue 😀
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