On Mon, 26 Aug 2024 20:51:35 GMT, Shaojin Wen <d...@openjdk.org> wrote:
>> This is a follow-up to PR #20273, which improves performance when the number >> of parameters exceeds 20. >> >> When the number of parameters is large, the possibility of reuse will be >> lower, so we can use the static concat method and write the length and coder >> directly into the bytecode to solve the performance regression problem. > > Shaojin Wen has updated the pull request with a new target base due to a > merge or a rebase. The pull request now contains nine commits: > > - optimize for CompactStrings is off > - Merge remote-tracking branch 'upstream/master' into > optim_concat_factory_202408 > > # Conflicts: > # src/java.base/share/classes/java/lang/invoke/StringConcatFactory.java > - add control flag `reuseThreshold` > - Revert "Optimize the construction of MethodType and MethodTypeDesc to > reduce memory allocation" > > This reverts commit 3bed7290f5cb987e86407f698fb0598f19d65628. > - Optimize the construction of MethodType and MethodTypeDesc to reduce > memory allocation > - revert code style > - from suggest > - Update > src/java.base/share/classes/java/lang/invoke/StringConcatFactory.java > > Co-authored-by: ExE Boss <3889017+exe-b...@users.noreply.github.com> > - support staticConcat I'm not too keen on `reuseThreshold` (perhaps `cacheThreshold`?) being enabled by default until we can get some tuning data from real world usage here. Does it harm applications by increasing number of generated classes by a large amount? Does the improved performance at each call-site matter, or is it more important to share common concat classes to reduce startup/warmup overheads? I'd be more at ease if we initially added this feature as an opt-in (`reuseThreshold` set to some value above 100) and then do a tuning pass at a future time. Disabling the generation of the `coder` methods if running with `-XX:-CompactStrings` is probably fine. Perhaps this should be split out to a separate PR. It adds some concerns regarding code pre-generation (might be best to always use the coder-checking `+CompactStrings` form when pre-generating to avoid bugs) ------------- PR Comment: https://git.openjdk.org/jdk/pull/20675#issuecomment-2311141871
