7264: Improve the performance of the JFR parser

[jpbempel]

When parsing a JFR file, StackFrames are the objects that are the most
deserialized using Readers.
By default, JMC core parser used a generic ReflectiveReaders
which use reflection to parser the structure. However, we have known
objects like stack frames where we could directly map to the typed
object instead on relying on reflection, which speed up significantly
the parsing.

Here the results for c5.2xlarge instance single threaded parsing with 24MB jfr recording with 100 iterations:

runs	baseline	specific readers optim	improvement
run 1	54,317ms	39,623ms	-27%
run 2	54,988ms	39,520ms	-28%
run 3	54,209ms	39,904ms	-26%

---

Progress

• Commit message must refer to an issue
• Change must be properly reviewed

Issue

• JMC-7264: Improve the performance of the JFR parser

Reviewers

• Erik Gahlin (@egahlin - Reviewer)

Reviewing

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[mlbridge]

Webrevs

• 01: Full - Incremental (1f82885f)
• 00: Full (e8b0048c)

[egahlin]

I never thought reflection was a good idea, and It makes sense to have specialised logic for known types, but I don't think the code should rely on the field order.

In earlier release of JMC (4.1), there was similar specialiced logic as yours, but it broke once the "truncated" field was added to the stack trace struct in JDK 7. The same thing can happen again.

Back then, there was a field accessor class where the index was looked up when the parser was created. When the value was read the accessor could use the pre-calculated index to get the correct value. It might even have been bytecode generated for optimal performance.

[jpbempel]

Agreed that this code is fragile.
I can precompute the index and make sure readers are meant for the field at construction time.
I will try that.

[egahlin]

Looks reasonable, even though the code will not handle removal of a field, but it's perhaps not as likely, and may fail anyway in the UI layer.

[openjdk]

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

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

7264: Improve the performance of the JFR parser

Reviewed-by: egahlin

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At the time when this comment was updated there had been 1 new commit pushed to the master branch:

• 8e2988e: 7268: Show icons for modifiers in the method profiling page

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[jpbempel]

/integrate

[openjdk]

Going to push as commit a2995a1.
Since your change was applied there has been 1 commit pushed to the master branch:

• 8e2988e: 7268: Show icons for modifiers in the method profiling page

Your commit was automatically rebased without conflicts.

[openjdk]

@jpbempel Pushed as commit a2995a1.

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