May 2025 - hotspot-jfr-dev

RFR: 8356968: JFR: Compilation event should be enabled for all compilations by default
by Aleksey Shipilev 22 Oct '25

22 Oct '25

In the field, we are using -XX:+PrintCompilation to track compiler performance. Alternatively, -Xlog:jit* prints the same. JFR has a the related jdk.Compilation event that gives us even richer diagnostics. Yet, that event is set at a very high threshold (1000ms), which skips almost all compilations! This threshold is set to such a high value from the beginning. It is fairly normal to have lots of compilations in 100+ ms range individually, and their sum impact is what we are after. Also, the compilations are normally quite rare, and there are a couple of thousands of compiles in most workloads, and they only happen sporadically. This means, the event count without any threshold is not high. Therefore, it would be convenient to make sure that basic Compilation event is enabled unconditionally, e.g. by dropping the default threshold to 0. See more logs in the bug itself. Additional testing: - [x] Ad-hoc tests with printing compilation events - [x] Linux x86_64 server fastdebug, `jdk_jfr` ------------- Commit messages: - Fix Changes: https://git.openjdk.org/jdk/pull/25247/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=25247&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8356968 Stats: 13 lines in 1 file changed: 0 ins; 12 del; 1 mod Patch: https://git.openjdk.org/jdk/pull/25247.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/25247/head:pull/25247 PR: https://git.openjdk.org/jdk/pull/25247

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RFR: 8354310: JFR: Inconsistent metadata in ZPageAllocation
by Joel Sikström 27 Jun '25

27 Jun '25

Hello, This PR fixes JFR metadata for ZPageAllocation after [JDK-8350441](https://bugs.openjdk.org/browse/JDK-8350441). ------------- Commit messages: - 8354310: JFR: Inconsistent metadata in ZPageAllocation Changes: https://git.openjdk.org/jdk/pull/24578/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24578&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8354310 Stats: 4 lines in 1 file changed: 0 ins; 0 del; 4 mod Patch: https://git.openjdk.org/jdk/pull/24578.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/24578/head:pull/24578 PR: https://git.openjdk.org/jdk/pull/24578

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RFR: 8357993: Use "stdin.encoding" for reading System.in with InputStreamReader/Scanner [hotspot]
by Volkan Yazici 10 Jun '25

10 Jun '25

Passes the `Charset` read from the `stdin.encoding` system property while creating `InputStreamReader` or `Scanner` instances for `System.in`. `stdin.encoding` is a recently added property for Java 25 in [JDK-8350703](https://bugs.openjdk.org/browse/JDK-8350703). Employing it throughout the entire code base is addressed by the parent ticket [JDK-8356893](https://bugs.openjdk.org/browse/JDK-8356893). JDK-8357993 this PR is addressing is a sub-task of JDK-8356893 and is concerned with only areas related to Hotspot. ------------- Commit messages: - Remove redundant assert - Discard changes unrelated with build and tools - Revert superfluous changes - Revert changes to 3rd parties in `com/sun/org/apache` - Revert `PandocFilter` changes - Use `stdin.encoding` in `InputStreamReader` and `Scanner` instantiations Changes: https://git.openjdk.org/jdk/pull/25542/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=25542&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8357993 Stats: 13 lines in 4 files changed: 4 ins; 0 del; 9 mod Patch: https://git.openjdk.org/jdk/pull/25542.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/25542/head:pull/25542 PR: https://git.openjdk.org/jdk/pull/25542

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RFR: 8351594: JFR: Rate-limited sampling of Java events
by Erik Gahlin 05 Jun '25

05 Jun '25

Could I have review of an enhancement that adds rate-limited sampling to Java event, including five events in the JDK (SocketRead, SocketWrite, FileRead, FileWrite, and JavaExceptionThrow). Testing: test/jdk/jdk/jfr Thanks Erik ------------- Commit messages: - Consistent annotation - Fix typos - Fix whitespace - Initial Changes: https://git.openjdk.org/jdk/pull/25559/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=25559&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8351594 Stats: 1230 lines in 37 files changed: 1028 ins; 87 del; 115 mod Patch: https://git.openjdk.org/jdk/pull/25559.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/25559/head:pull/25559 PR: https://git.openjdk.org/jdk/pull/25559

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Re: RFR: 8342818: Implement JEP 509: JFR CPU-Time Profiling [v10]
by Johannes Bechberger 04 Jun '25

04 Jun '25

> This is the code for the [JEP 509: CPU Time based profiling for JFR](https://openjdk.org/jeps/509). > > Currently tested using [this test suite](https://github.com/parttimenerd/basic-profiler-tests). This runs profiles the [Renaissance](https://renaissance.dev/) benchmark with > - ... different heap sizes > - ... different GCs > - ... different samplers (the standard JFR and the new CPU Time Sampler and both) > - ... different JFR recording durations > - ... different chunk-sizes Johannes Bechberger has updated the pull request incrementally with one additional commit since the last revision: Don't mention throttling ------------- Changes: - all: https://git.openjdk.org/jdk/pull/25302/files - new: https://git.openjdk.org/jdk/pull/25302/files/d071acc9..cfbc25a0 Webrevs: - full: https://webrevs.openjdk.org/?repo=jdk&pr=25302&range=09 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=25302&range=08-09 Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod Patch: https://git.openjdk.org/jdk/pull/25302.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/25302/head:pull/25302 PR: https://git.openjdk.org/jdk/pull/25302

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Re: RFR: 8342818: Implement JEP 509: JFR CPU-Time Profiling [v24]
by Johannes Bechberger 02 Jun '25

02 Jun '25

> This is the code for the [JEP 509: CPU Time based profiling for JFR](https://openjdk.org/jeps/509). > > Currently tested using [this test suite](https://github.com/parttimenerd/basic-profiler-tests). This runs profiles the [Renaissance](https://renaissance.dev/) benchmark with > - ... different heap sizes > - ... different GCs > - ... different samplers (the standard JFR and the new CPU Time Sampler and both) > - ... different JFR recording durations > - ... different chunk-sizes Johannes Bechberger has updated the pull request incrementally with one additional commit since the last revision: Fix tiny issue ------------- Changes: - all: https://git.openjdk.org/jdk/pull/25302/files - new: https://git.openjdk.org/jdk/pull/25302/files/adcbec51..16faa421 Webrevs: - full: https://webrevs.openjdk.org/?repo=jdk&pr=25302&range=23 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=25302&range=22-23 Stats: 2 lines in 2 files changed: 1 ins; 1 del; 0 mod Patch: https://git.openjdk.org/jdk/pull/25302.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/25302/head:pull/25302 PR: https://git.openjdk.org/jdk/pull/25302

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RFR: 8356698: JFR: @Contextual
by Erik Gahlin 02 Jun '25

02 Jun '25

Could I have a review of a new annotation that can be used to annotate a field as contextual. Testing: jdk/jdk/jfr + tier1 Thanks Erik ------------- Commit messages: - Simplification and cleanup - Merge - Remove mistakenly added file - Update - Whitspace - Initial Changes: https://git.openjdk.org/jdk/pull/25249/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=25249&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8356698 Stats: 706 lines in 6 files changed: 698 ins; 3 del; 5 mod Patch: https://git.openjdk.org/jdk/pull/25249.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/25249/head:pull/25249 PR: https://git.openjdk.org/jdk/pull/25249

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Re: RFR: 8342818: Implement JEP 509: JFR CPU-Time Profiling [v5]
by Johannes Bechberger 02 Jun '25

02 Jun '25

> This is the code for the [JEP 509: CPU Time based profiling for JFR](https://openjdk.org/jeps/509). > > Currently tested using [this test suite](https://github.com/parttimenerd/basic-profiler-tests). This runs profiles the [Renaissance](https://renaissance.dev/) benchmark with > - ... different heap sizes > - ... different GCs > - ... different samplers (the standard JFR and the new CPU Time Sampler and both) > - ... different JFR recording durations > - ... different chunk-sizes Johannes Bechberger has updated the pull request incrementally with one additional commit since the last revision: Fix compilation ------------- Changes: - all: https://git.openjdk.org/jdk/pull/25302/files - new: https://git.openjdk.org/jdk/pull/25302/files/eaca165d..5e03c9cf Webrevs: - full: https://webrevs.openjdk.org/?repo=jdk&pr=25302&range=04 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=25302&range=03-04 Stats: 44 lines in 5 files changed: 18 ins; 5 del; 21 mod Patch: https://git.openjdk.org/jdk/pull/25302.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/25302/head:pull/25302 PR: https://git.openjdk.org/jdk/pull/25302

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Re: RFR: 8342818: Implement JEP 509: JFR CPU-Time Profiling [v25]
by Johannes Bechberger 01 Jun '25

01 Jun '25

> This is the code for the [JEP 509: CPU Time based profiling for JFR](https://openjdk.org/jeps/509). > > Currently tested using [this test suite](https://github.com/parttimenerd/basic-profiler-tests). This runs profiles the [Renaissance](https://renaissance.dev/) benchmark with > - ... different heap sizes > - ... different GCs > - ... different samplers (the standard JFR and the new CPU Time Sampler and both) > - ... different JFR recording durations > - ... different chunk-sizes Johannes Bechberger has updated the pull request incrementally with one additional commit since the last revision: Remove debug printf ------------- Changes: - all: https://git.openjdk.org/jdk/pull/25302/files - new: https://git.openjdk.org/jdk/pull/25302/files/16faa421..3a10d552 Webrevs: - full: https://webrevs.openjdk.org/?repo=jdk&pr=25302&range=24 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=25302&range=23-24 Stats: 1 line in 1 file changed: 0 ins; 1 del; 0 mod Patch: https://git.openjdk.org/jdk/pull/25302.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/25302/head:pull/25302 PR: https://git.openjdk.org/jdk/pull/25302

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Re: RFR: 8342818: Implement JEP 509: JFR CPU-Time Profiling [v17]
by Johannes Bechberger 31 May '25

31 May '25

> This is the code for the [JEP 509: CPU Time based profiling for JFR](https://openjdk.org/jeps/509). > > Currently tested using [this test suite](https://github.com/parttimenerd/basic-profiler-tests). This runs profiles the [Renaissance](https://renaissance.dev/) benchmark with > - ... different heap sizes > - ... different GCs > - ... different samplers (the standard JFR and the new CPU Time Sampler and both) > - ... different JFR recording durations > - ... different chunk-sizes Johannes Bechberger has updated the pull request incrementally with one additional commit since the last revision: Remove assertion ------------- Changes: - all: https://git.openjdk.org/jdk/pull/25302/files - new: https://git.openjdk.org/jdk/pull/25302/files/d49b0084..d91f5672 Webrevs: - full: https://webrevs.openjdk.org/?repo=jdk&pr=25302&range=16 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=25302&range=15-16 Stats: 1 line in 1 file changed: 0 ins; 1 del; 0 mod Patch: https://git.openjdk.org/jdk/pull/25302.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/25302/head:pull/25302 PR: https://git.openjdk.org/jdk/pull/25302

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