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8253030: ZGC: Change ZMarkCompleteTimeout unit to microseconds #120

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@pliden pliden commented Sep 10, 2020

The ZMarkCompleteTimeout is currently specified in milliseconds, and its value is 1 (i.e. as low as it can be). In preparation for using a lower time out value than 1ms we should change the ZMarkCompleteTimeout unit to be microseconds, instead of milliseconds.


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  • JDK-8253030: ZGC: Change ZMarkCompleteTimeout unit to microseconds

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$ git fetch https://git.openjdk.java.net/jdk pull/120/head:pull/120
$ git checkout pull/120

@pliden pliden changed the title 8253030: Mark timeout 8253030: ZGC: Change ZMarkCompleteTimeout unit to microseconds Sep 10, 2020
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👋 Welcome back pliden! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

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@openjdk openjdk bot commented Sep 10, 2020

@pliden The following label will be automatically applied to this pull request: hotspot.

When this pull request is ready to be reviewed, an RFR email will be sent to the corresponding mailing list. If you would like to change these labels, use the /label (add|remove) "label" command.

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@openjdk openjdk bot added the hotspot label Sep 10, 2020
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@pliden pliden commented Sep 10, 2020

/cc hotspot-gc

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@openjdk openjdk bot added the hotspot-gc label Sep 10, 2020
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@pliden pliden commented Sep 10, 2020

/cc remove hotspot

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@pliden pliden marked this pull request as ready for review Sep 10, 2020
@openjdk openjdk bot added the rfr label Sep 10, 2020
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@mlbridge mlbridge bot commented Sep 10, 2020

Webrevs

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@kimbarrett kimbarrett left a comment

Change looks good. But I wonder, why choose microseconds as the units? That seems to be almost never used in HotSpot.

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@openjdk openjdk bot commented Sep 11, 2020

@pliden This change now passes all automated pre-integration checks. In addition to the automated checks, the change must also fulfill all project specific requirements

After integration, the commit message will be:

8253030: ZGC: Change ZMarkCompleteTimeout unit to microseconds

Reviewed-by: kbarrett, stefank, eosterlund
  • If you would like to add a summary, use the /summary command.
  • To credit additional contributors, use the /contributor command.
  • To add additional solved issues, use the /issue command.

Since the source branch of this PR was last updated there have been 19 commits pushed to the master branch:

  • f978f6f: 8252689: Classes are loaded from jrt:/java.base even when CDS is used
  • c5e63b6: 8248186: Move CDS C++ vtable code to cppVtables.cpp
  • 03a4df0: 8244778: Archive full module graph in CDS
  • 998ce78: 8252543: [JVMCI] Libgraal can deadlock in blocking compilation mode
  • b1b0f0b: 8253066: typo in Stream.mapMulti
  • 306b166: 8253033: CheckUnhandledOops check fails in ThreadSnapshot::initialize…
  • 5c0d985: 8253060: remove test/hotspot/jtreg/test_env.sh
  • 9525186: 8253031: git jcheck complains about invalid tags in jdk repo after fix for JDK-8252844
  • 7f27d0b: 8236142: DocTrees should provide getCharacters(EntityTree)
  • e7a1b9b: 8252981: ObjectMonitor::object() cleanup changes extracted from JDK-8247281
  • ... and 9 more: https://git.openjdk.java.net/jdk/compare/44a74dac957ca7cc10eaddafb6bd32b74a8d84c8...master

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid automatic rebasing, please merge master into your branch, and then specify the current head hash when integrating, like this: /integrate f978f6fe8ab57ab815f61dc0571df955db2663d5.

➡️ To integrate this PR with the above commit message to the master branch, type /integrate in a new comment.

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@openjdk openjdk bot added the ready label Sep 11, 2020
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@pliden pliden commented Sep 11, 2020

@kimbarrett Thanks for reviewing. I used micros because it seems like the natural unit to use here. Using nanos seems a bit overkill, as we will never need that precision and it would just add a bunch of zeros to the constant, which I'm not sure would help readability. What unit did you have in mind?

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@fisk fisk left a comment

Looks good.

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@mlbridge mlbridge bot commented Sep 11, 2020

Mailing list message from Kim Barrett on hotspot-gc-dev:

On Sep 11, 2020, at 5:52 AM, Per Lid?n <pliden at openjdk.java.net> wrote:

On Fri, 11 Sep 2020 01:16:34 GMT, Kim Barrett <kbarrett at openjdk.org> wrote:

The ZMarkCompleteTimeout is currently specified in milliseconds, and its value is 1 (i.e. as low as it can be). In
preparation for using a lower time out value than 1ms we should change the ZMarkCompleteTimeout unit to be
microseconds, instead of milliseconds.

Change looks good. But I wonder, why choose microseconds as the units? That seems to be almost never used in HotSpot.

@kimbarrett Thanks for reviewing. I used micros because it seems like the natural unit to use here. Using nanos seems a
bit overkill, as we will never need that precision and it would just add a bunch of zeros to the constant, which I'm
not sure would help readability. What unit did you have in mind?

Nanos would have been my choice, since that's widely used. The configuration
isn't user-facing, so some extra zeros doesn't seem important to me. But I
don't feel strongly about it; it just seemed an odd choice to me, since micros are
so rarely used elsewhere in our code.

I?ll go click the reviewed button now.

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@pliden pliden commented Sep 14, 2020

/integrate

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@openjdk openjdk bot closed this Sep 14, 2020
@openjdk openjdk bot added integrated and removed ready rfr labels Sep 14, 2020
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@openjdk openjdk bot commented Sep 14, 2020

@pliden Since your change was applied there have been 19 commits pushed to the master branch:

  • f978f6f: 8252689: Classes are loaded from jrt:/java.base even when CDS is used
  • c5e63b6: 8248186: Move CDS C++ vtable code to cppVtables.cpp
  • 03a4df0: 8244778: Archive full module graph in CDS
  • 998ce78: 8252543: [JVMCI] Libgraal can deadlock in blocking compilation mode
  • b1b0f0b: 8253066: typo in Stream.mapMulti
  • 306b166: 8253033: CheckUnhandledOops check fails in ThreadSnapshot::initialize…
  • 5c0d985: 8253060: remove test/hotspot/jtreg/test_env.sh
  • 9525186: 8253031: git jcheck complains about invalid tags in jdk repo after fix for JDK-8252844
  • 7f27d0b: 8236142: DocTrees should provide getCharacters(EntityTree)
  • e7a1b9b: 8252981: ObjectMonitor::object() cleanup changes extracted from JDK-8247281
  • ... and 9 more: https://git.openjdk.java.net/jdk/compare/44a74dac957ca7cc10eaddafb6bd32b74a8d84c8...master

Your commit was automatically rebased without conflicts.

Pushed as commit 07da3a1.

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

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@pliden pliden deleted the 8253030_mark_timeout branch Sep 14, 2020
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