> This update removes a significant performance overhead when an application > running millions of virtual threads is started with the JDWP agent but > debugger has not been attached. The overhead is 4X-6X slowdown. > The tested app normally (without debug agent) takes around 3+ seconds. With > debug agent enabled it takes 14 seconds and more. The performance overhead is > caused by the `jvmti_yield_cleanup()` recursively calling > `JvmtiExport::continuation_yield_cleanup()`. The reason of this overhead is > because the function `JvmtiExport::can_post_frame_pop()` is used to identify > a need for the JVMTI cleanup which is not precise and triggers unneeded work > when debugger has not been attached yet. The fix is to trigger the JVMTI > cleanup with new function: `bool JvmtiExport::has_frame_pops(JavaThread* > thread)`. > > Testing: > - Insure the 4X-6X slowdown is gone for application an application running > millions of virtual threads and started with the JDWP agent > - Mach5 tiers 1-6 are all passed
Serguei Spitsyn has updated the pull request incrementally with one additional commit since the last revision: fix minimal build broken by incorrect macro usage ------------- Changes: - all: https://git.openjdk.org/jdk/pull/27403/files - new: https://git.openjdk.org/jdk/pull/27403/files/0f63bb17..4b0478fc Webrevs: - full: https://webrevs.openjdk.org/?repo=jdk&pr=27403&range=01 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=27403&range=00-01 Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod Patch: https://git.openjdk.org/jdk/pull/27403.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/27403/head:pull/27403 PR: https://git.openjdk.org/jdk/pull/27403
