Remove needless locking and volatile access from QueryPhaseResultConsumer #119808
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…umer No need to have any synchronization here (it's obviously pointless since we are sorting the plain `buffer` outside of the block). By forking the execution of `reduce` we establish a happens before edge already (and if we didn't fork we wouldn't have to worry about a mutx anyway ...). => remove this, remove needless volatile from partial results flag and reduce volatile accesses. Also, while we're at it, `null` out the partial merge result early which might save non-trivial heap in some scenarios and run with a local reference.
original-brownbear
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Pinging @elastic/es-search-foundations (Team:Search Foundations) |
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I believe that this is entirely irrelevant after #119984 ? Can we close it? |
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Oh right sorry, actually the conclusion here was that the locking can't fully go away for now :) closing+thanks! |
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No need to have any synchronization here (it's obviously pointless since we are sorting the plain
bufferoutside of the block).By forking the execution of
reducewe establish a happens before edge already (and if we didn't fork we wouldn't have to worry about thread-safety anyway ...). => remove this, remove needless volatile from partial results flag and reduce volatile accesses. Also, while we're at it,nullout the partial merge result early which might save non-trivial heap in some scenarios and run with a local reference.Mainly motivated by the desire to execute
reduceon transport threads when there's no aggs where synchronization ,even if not contended in this case, just wastes needless cycles and forces the reader to think about its latency implications.