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8264311: Heap object statistics #1

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@rkennke rkennke commented May 5, 2021

For Lilliput evaluation, it would be useful to be able to get some statistics about heap objects, e.g. how many objects there typically are, what is their (average) size, how big is the live data set, how many objecs have an identity hash code and how many objects are locked. Some of that information may be useful for general purpose too, e.g. the avg live data set and object size/count information might be quite useful to have.

Heap object statistics can be gathered and printed by invoking java with -XX:+UnlockDiagnosticVMOptions -XX:+HeapObjectStats -Xlog:heap+stats. It will impact performance of the workload. The sampling interval can be specificed by -XX:HeapObjectStatsSamplingInterval=X (in ms) and defaults to 500 (ms).

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  • Some manual tests, verifying the plausability of the output by hand
  • tier1
  • tier2

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  • Change must not contain extraneous whitespace
  • Change must be properly reviewed

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Checkout this PR locally:
$ git fetch https://git.openjdk.java.net/lilliput pull/1/head:pull/1
$ git checkout pull/1

Update a local copy of the PR:
$ git checkout pull/1
$ git pull https://git.openjdk.java.net/lilliput pull/1/head

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Checkout this PR locally:
$ git pr checkout 1

View PR using the GUI difftool:
$ git pr show -t 1

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Download this PR as a diff file:
https://git.openjdk.java.net/lilliput/pull/1.diff

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@bridgekeeper bridgekeeper bot commented May 5, 2021

👋 Welcome back rkennke! 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.

@openjdk openjdk bot added the rfr label May 5, 2021

class HeapObjectStatistics : public CHeapObj<mtGC> {
private:
static const int HISTOGRAM_SIZE = 16;

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shipilev May 5, 2021
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This fields looks unused.

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@mlbridge mlbridge bot commented May 5, 2021

Webrevs

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@rkennke rkennke commented May 7, 2021

/integrate

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@openjdk openjdk bot commented May 7, 2021

@rkennke This PR has not yet been marked as ready for integration.

@rkennke rkennke requested a review from shipilev May 7, 2021
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@shipilev shipilev commented May 7, 2021

I think my review does not count here, because I am in "Commiter" role here. You can relax this by doing e.g. https://github.com/openjdk/jcstress/blob/master/.jcheck/conf#L39-L41

@rkennke rkennke force-pushed the rkennke:heap-statistics branch from 379caec to 9a3ea63 May 7, 2021
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@rkennke rkennke commented May 7, 2021

I think my review does not count here, because I am in "Commiter" role here. You can relax this by doing e.g. https://github.com/openjdk/jcstress/blob/master/.jcheck/conf#L39-L41

Right. I fixed it in master branch, and rebased this PR on the master. Let's do a last attempt at getting this 'properly reviewed' and failing that I'll bypass the bot.

@rkennke rkennke requested a review from shipilev May 7, 2021
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@openjdk openjdk bot commented May 7, 2021

@rkennke 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:

8264311: Heap object statistics

Reviewed-by: shade

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 no new commits pushed to the master branch. If another commit should be pushed before you perform the /integrate command, your PR will be automatically rebased. If you prefer to avoid any potential automatic rebasing, please check the documentation for the /integrate command for further details.

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

@openjdk openjdk bot added the ready label May 7, 2021
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@rkennke rkennke commented May 7, 2021

/integrate

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@openjdk openjdk bot commented May 7, 2021

@rkennke An unexpected error occurred during integration. No push attempt will be made. The error has been logged and will be investigated. It is possible that this error is caused by a transient issue; feel free to retry the operation.

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@rkennke rkennke commented May 10, 2021

/integrate

@openjdk openjdk bot closed this May 10, 2021
@openjdk openjdk bot added integrated and removed ready rfr labels May 10, 2021
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@openjdk openjdk bot commented May 10, 2021

@rkennke Pushed as commit dce94d8.

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

@rkennke rkennke mentioned this pull request May 10, 2021
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