JDK-8273979: move some os time related functions to os_posix for POSIX platforms #5582

MBaesken · 2021-09-20T13:16:42Z

There are a couple of time related functions in os_ for Linux, BSD+Mac and AIX that are pretty similar (or identical) across the platforms and can be centralized in os_posix .
While doing so, I noticed that os::supports_vtime() returns always true , on Posix and also on Windows, so we might remove it completely if this prefered ?

Best regards , Matthias

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JDK-8273979: move some os time related functions to os_posix for POSIX platforms

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David Holmes (@dholmes-ora - Reviewer)
Lutz Schmidt (@RealLucy - Reviewer)

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bridgekeeper · 2021-09-20T13:17:49Z

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openjdk · 2021-09-20T13:44:27Z

@MBaesken The following label will be automatically applied to this pull request:

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mlbridge · 2021-09-20T13:49:36Z

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dholmes-ora

Hi Matthias,

Generally this refactoring looks good, though I have a request to restore some of the code - see comments below. Also could you clarify where functions were only "pretty similar" rather than identical as we don't want to introduce subtle incompatibilities.

I think supports_vtime() could probably be removed in a separate RFE.

Thanks,
David

dholmes-ora · 2021-09-21T05:57:40Z

src/hotspot/os/aix/os_aix.cpp

@@ -994,49 +977,6 @@ jlong os::javaTimeNanos() {
  }
 }

-void os::javaTimeNanos_info(jvmtiTimerInfo *info_ptr) {


Please restore this. As has been discussed in previous refactorings in this code if there is a platform specific definition of javaTimeNanos then we should keep the platform specific definition of javaTimeNanos_info, even if it happens to be the same as on other platforms. Otherwise if the javaTimeNanos code were changed one would not realise they also may have to change javaTimenanos_info.

dholmes-ora · 2021-09-21T06:01:14Z

src/hotspot/os/bsd/os_bsd.cpp

@@ -804,52 +784,8 @@ jlong os::javaTimeNanos() {
  // See https://blogs.oracle.com/dave/entry/cas_and_cache_trivia_invalidate
  return (prev == obsv) ? now : obsv;
 }
-
-void os::javaTimeNanos_info(jvmtiTimerInfo *info_ptr) {


Please restore as per previous comment.

dholmes-ora · 2021-09-21T06:09:16Z

src/hotspot/os/posix/os_posix.cpp

+#if defined(_ALLBSD_SOURCE)
+static int clock_tics_per_sec = CLK_TCK;
+#else
+static int clock_tics_per_sec = 100;
+#endif


Can't we just defer the conditional initialization to the init() function where we already have to conditionally initialise.

…init

dholmes-ora

Thanks Matthias - updates look good.

David

openjdk · 2021-09-21T07:16:43Z

@MBaesken This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

8273979: move some os time related functions to os_posix for POSIX platforms

Reviewed-by: dholmes, lucy

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been 44 new commits pushed to the master branch:

d9872ba: 8273590: Move helper classes in G1 post evacuation sub tasks to cpp files
688b3fe: 8274070: Rectify problemlist platform for failing test on macos12
eeaf43b: 8274114: ProblemList serviceability/sa/TestJhsdbJstackMixed.java on linux-aarch64 in -Xcomp mode
517405e: 8273965: some testlibrary_tests/ir_framework tests fail when c1 disabled
11cddd3: 8272114: Unused _last_state in osThread_windows
cbe57e8: 8273684: Replace usages of java.util.Stack with ArrayDeque
a72c8aa: 8273921: Refactor NSK/JDI tests to create thread using factory
161fdb4: 8273935: (zipfs) Files.getFileAttributeView() throws UOE instead of returning null when view not supported
0fc47e9: 8266666: Implementation for snippets
6d91a3e: 8269039: Disable SHA-1 Signed JARs
... and 34 more: https://git.openjdk.java.net/jdk/compare/d2388b7a0f4bfb55ea0d5648175e3253f30a4302...master

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MBaesken · 2021-09-21T07:42:56Z

Hi David, I brought back os::javaTimeNanos_info following your suggestion and adjusted the initialization of 'clock_tics_per_sec ' in os_posix.

Also could you clarify where functions were only "pretty similar" rather than identical as we don't want to introduce subtle incompatibilities

Sure, went through them and this is what I found
os::elapsedTime() identical except comment
os::elapsed_counter() identical
os::elapsed_frequency() identical
os::supports_vtime() identical
os::getTimesSecs identical
os::local_time_string identical
os::localtime_pd identical

I think supports_vtime() could probably be removed in a separate RFE.

OK, I opened https://bugs.openjdk.java.net/browse/JDK-8274051 .

RealLucy · 2021-09-21T15:28:35Z

src/hotspot/os/linux/os_linux.cpp

@@ -171,8 +171,6 @@ os::Linux::mallinfo_func_t os::Linux::_mallinfo = NULL;
 os::Linux::mallinfo2_func_t os::Linux::_mallinfo2 = NULL;
 #endif // __GLIBC__

-static jlong initial_time_count=0;
-
 static int clock_tics_per_sec = 100;



In os_linux.cpp, clock_tics_per_sec is used for elapsed time calculations as well as for cpu time calculations. In addition, clock_tics_per_sec is set (reinitialised) in os::init(). Are we sure that _SC_CLK_TCK evaluates to 100? If no, do we then potentially calculate wrong elapsed times after moving the code to os_posix?

RealLucy

My previous comment about clock_ticks_per_sec is obsolete. Just saw the initialisation in os::Posix::init(void) now is the same as in os::init(). The static init value is in effect only for the short time until os::init() is invoked.
Looks good to me.

MBaesken · 2021-09-22T08:17:53Z

My previous comment about clock_ticks_per_sec is obsolete. Just saw the initialisation in os::Posix::init(void) now is the same as in os::init(). The static init value is in effect only for the short time until os::init() is invoked.
Looks good to me.

Hi Lutz, thanks for the review .
In case of worries about the short time frame between posix and linux init functions, we could introduce 'os::clock_ticks_per_sec()' and move this to os_linux, os_aix os_bsd etc. to have the initialization at one single point.
Not sure if this is worth the effort?

Best regards, Matthias

RealLucy · 2021-09-22T08:21:34Z

I would not add this complexity. Just leave it as it is.

MBaesken · 2021-09-23T05:33:06Z

/integrate

openjdk · 2021-09-23T05:34:28Z

Going to push as commit 1c6fa11.
Since your change was applied there have been 65 commits pushed to the master branch:

45adc92: 8273578: javax/swing/JMenu/4515762/bug4515762.java fails on macOS 12
0fbbe4c: 8274033: Some tier-4 CDS EpsilonGC tests throw OOM
9d3379b: 8267356: AArch64: Vector API SVE codegen support
6031388: 8273714: jdk/jfr/api/consumer/TestRecordedFrame.java still times out after JDK-8273047
8821b00: 8205137: Remove Applet support from SwingSet2
57fe11c: 8274120: [JVMCI] CompileBroker should resolve parameter types for JVMCI compiles
81d4164: 8272759: (fc) java/nio/channels/FileChannel/Transfer2GPlus.java failed in timeout
da38ced: 8271602: Add Math.ceilDiv() family parallel to Math.floorDiv() family
d39aad9: 8273924: ArrayIndexOutOfBoundsException thrown in java.util.JapaneseImperialCalendar.add()
c9de806: 8274039: codestrings gtest fails when hsdis is present
... and 55 more: https://git.openjdk.java.net/jdk/compare/d2388b7a0f4bfb55ea0d5648175e3253f30a4302...master

Your commit was automatically rebased without conflicts.

openjdk · 2021-09-23T05:34:39Z

@MBaesken Pushed as commit 1c6fa11.

💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.

rvansa · 2024-08-28T15:26:24Z

/backport jdk17u-dev

openjdk · 2024-08-28T15:27:01Z

@rvansa the backport was successfully created on the branch backport-rvansa-1c6fa113-master in my personal fork of openjdk/jdk17u-dev. To create a pull request with this backport targeting openjdk/jdk17u-dev:master, just click the following link:

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Hi all,

This pull request contains a backport of commit 1c6fa113 from the openjdk/jdk repository.

The commit being backported was authored by Matthias Baesken on 23 Sep 2021 and was reviewed by David Holmes and Lutz Schmidt.

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JDK-8273979

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openjdk bot added the rfr Pull request is ready for review label Sep 20, 2021

openjdk bot added the hotspot-runtime hotspot-runtime-dev@openjdk.org label Sep 20, 2021

dholmes-ora suggested changes Sep 21, 2021

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Restored javaTimeNanos_info in os-files, adjusted clock_tics_per_sec …

91bd15a

…init

dholmes-ora approved these changes Sep 21, 2021

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JDK-8273979: move some os time related functions to os_posix for POSIX platforms #5582

JDK-8273979: move some os time related functions to os_posix for POSIX platforms #5582

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JDK-8273979: move some os time related functions to os_posix for POSIX platforms #5582

JDK-8273979: move some os time related functions to os_posix for POSIX platforms #5582

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