8260337: Optimize ImageReader lookup, used by Class.getResource #2212

cl4es · 2021-01-25T00:05:52Z

This patch optimizes the code paths exercised by String.class.getResource("String.class") by:

Adding an ASCII fast-path to methods verifying strings in the jimage, which can then be done allocation-free
Avoiding the allocation of the long[8] attributes when verifying only for the purpose of verifying a path exists
Using the JNUA.create fast-path in SystemModuleReader (which should be OK since we just verified the given name is a JRT path)
Remove a redundant check in Class::resolveName and fitting the StringBuilder to size

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Issue

JDK-8260337: Optimize ImageReader lookup, used by Class.getResource

Reviewers

Jim Laskey (@JimLaskey - Reviewer)
Athijegannathan Sundararajan (@sundararajana - Reviewer)

Download

$ git fetch https://git.openjdk.java.net/jdk pull/2212/head:pull/2212
$ git checkout pull/2212

…SystemModuleReader, improve Class.resolveName

bridgekeeper · 2021-01-25T00:06:48Z

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openjdk · 2021-01-25T00:07:58Z

@cl4es The following label will be automatically applied to this pull request:

core-libs

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 pull request command.

cl4es · 2021-01-25T00:08:25Z

On the provided benchmark we can observe a 2x speed-up and a 70% reduction in allocation.

Baseline:

Benchmark                                                      Mode  Cnt     Score     Error   Units
ClassGetResource.stringClass                                   avgt    5  2885.403 ± 309.787   ns/op
ClassGetResource.stringClass:·gc.alloc.rate.norm               avgt    5  1368.124 ±   0.056    B/op

Patch:

Benchmark                                                      Mode  Cnt     Score     Error   Units
ClassGetResource.stringClass                                   avgt    5  1411.980 ± 155.877   ns/op
ClassGetResource.stringClass:·gc.alloc.rate.norm               avgt    5   408.038 ±   0.043    B/op

…st etc)

mlbridge · 2021-01-25T15:30:50Z

Webrevs

01: Full - Incremental (096e64b)
00: Full (ad95b49)

src/java.base/share/classes/jdk/internal/module/SystemModuleFinders.java

JimLaskey

Nice clean up. LGTM

openjdk · 2021-01-27T18:23:24Z

@cl4es 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:

8260337: Optimize ImageReader lookup, used by Class.getResource

Reviewed-by: jlaskey, sundar

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 236 new commits pushed to the master branch:

906faca: 8260372: [PPC64] Add support for JDK-8210498 and JDK-8222841
b38d5be: 8261340: Fix 'deprecated' warnings in the vmTestbase/nsk tests
b0e7e5a: 8261263: Simplify javadoc link code
8ebed28: 8261237: remove isClassPathAttributePresent method
5183d8a: 8260355: AArch64: deoptimization stub should save vector registers
5d8204b: 8261368: The new TestNullSetColor test is placed in the wrong group
f03e839: 8261127: Cleanup THREAD/TRAPS/CHECK usage in CDS code
7451962: 8129776: The optimized Stream returned from Files.lines should unmap the mapped byte buffer (if created) when closed
ad525bc: 8261281: Linking jdk.jpackage fails for linux aarch32 builds after 8254702
2fd8ed0: 8240632: Note differences between IEEE 754-2019 math lib special cases and java.lang.Math
... and 226 more: https://git.openjdk.java.net/jdk/compare/535c2927b6e0004ffa1ab5af3e19a622ab14d9f1...master

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this 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.

AlanBateman · 2021-01-31T15:04:33Z

@JimLaskey Do you have anything that documents the jimage format that could be checked into the repo to help with future changes in this change? Clearly any such document would need a warning in 96pt font that the format is JDK internal, submit to change from build to build, etc. but it could be helpful when working on this code.

mlbridge · 2021-01-31T15:42:43Z

Mailing list message from Jim Laskey on core-libs-dev:

I?ve been handing out the original jimage docs on request. Surprisingly, it?s still accurate. Will dig up on Monday to post.

??

mlbridge · 2021-02-02T15:19:46Z

Mailing list message from Jim Laskey on core-libs-dev:

Here is the original document (it's available in the jigsaw wiki)

How would you like it flushed out?

Cheers,

-- Jim

On Jan 31, 2021, at 11:40 AM, Jim Laskey <james.laskey at oracle.com> wrote:

I?ve been handing out the original jimage docs on request. Surprisingly, it?s still accurate. Will dig up on Monday to post.

??

cl4es · 2021-02-07T19:36:09Z

@sundararajana @AlanBateman - can I solicit a second review on this? Or an OK from Alan to go ahead and push with the one review.

sundararajana

LGTM

cl4es · 2021-02-09T15:31:57Z

@JimLaskey @sundararajana - thanks for reviewing!

/integrate

openjdk · 2021-02-09T15:32:59Z

@cl4es Since your change was applied there have been 237 commits pushed to the master branch:

f0bd9db: 8257569: Failure observed with JfrVirtualMemory::initialize
906faca: 8260372: [PPC64] Add support for JDK-8210498 and JDK-8222841
b38d5be: 8261340: Fix 'deprecated' warnings in the vmTestbase/nsk tests
b0e7e5a: 8261263: Simplify javadoc link code
8ebed28: 8261237: remove isClassPathAttributePresent method
5183d8a: 8260355: AArch64: deoptimization stub should save vector registers
5d8204b: 8261368: The new TestNullSetColor test is placed in the wrong group
f03e839: 8261127: Cleanup THREAD/TRAPS/CHECK usage in CDS code
7451962: 8129776: The optimized Stream returned from Files.lines should unmap the mapped byte buffer (if created) when closed
ad525bc: 8261281: Linking jdk.jpackage fails for linux aarch32 builds after 8254702
... and 227 more: https://git.openjdk.java.net/jdk/compare/535c2927b6e0004ffa1ab5af3e19a622ab14d9f1...master

Your commit was automatically rebased without conflicts.

Pushed as commit 2f893c2.

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

cl4es added 5 commits January 22, 2021 16:04

Improve jimage string reading

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ce1b1f0

Add working micro, cleanup and fix code

ed66159

Invert length for non-ASCII case

159631f

Make ImageLocation lookup mostly allocation-free, use JNUA.create in …

2f28f03

…SystemModuleReader, improve Class.resolveName

Merge branch 'master' into jrt_getString

0e3df57

openjdk bot added the core-libs label Jan 25, 2021

cl4es changed the title ~~8260337: Optimize Class.getResource lookups of system module resources~~ 8260337: Optimize ImageReader lookup, used by Class.getResource Jan 25, 2021

cl4es added 4 commits January 25, 2021 12:13

Fix offsets to properly find extension-less resources (ModuleReaderTe…

4648651

…st etc)

Minor cleanup, remove some code duplication

09ce8c1

More cleanups, remove redundant null checks, synchronization

7d4ca62

Remove more redundant checks

ad95b49

cl4es marked this pull request as ready for review January 25, 2021 15:26

openjdk bot added the rfr label Jan 25, 2021

AlanBateman reviewed Jan 25, 2021

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src/java.base/share/classes/jdk/internal/module/SystemModuleFinders.java Outdated Show resolved Hide resolved

Copyrights and rename containsLocation

096e64b

JimLaskey approved these changes Jan 27, 2021

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openjdk bot added the ready label Jan 27, 2021

sundararajana approved these changes Feb 9, 2021

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openjdk bot closed this Feb 9, 2021

openjdk bot added the integrated label Feb 9, 2021

openjdk bot removed ready rfr labels Feb 9, 2021

stsypanov mentioned this pull request May 6, 2021

8266622: Optimize Class.descriptorString() and Class.getCanonicalName0() #3903

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8260337: Optimize ImageReader lookup, used by Class.getResource #2212

8260337: Optimize ImageReader lookup, used by Class.getResource #2212

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8260337: Optimize ImageReader lookup, used by Class.getResource #2212

8260337: Optimize ImageReader lookup, used by Class.getResource #2212

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