8369346: Remove default value of and deprecate the MaxRAM flag

[jsikstro]

Hello,

Please see the CSR for a more detailed explanation and specific information regarding the deprecation of the flag. To summarize, the JVM is well-equiped to detect system memory and handle potential truncation errors (see JDK-8367413 ), making MaxRAM largely redundant. Removing the default value from MaxRAM mainly impacts systems with more memory than the default (128GB on 64-bit systems and 4GB on 32-bit systems) that are running with -XX:-UseCompressedOops or -XX:+UseZGC, which disable compressed oops. We recommend users to use well-supported flags such as -Xms and -Xmx to influence heap sizing instead.

MaxRAM is used to a very small extent to influence memory allocation in JDK tests, where MaxRAMPercentage is much more common. When MaxRAM is eventually obsoleted, the few affected tests will need to be updated or use alternative flags.

Testing:

• Oracle's tier1-8

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Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
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• Commit message must refer to an issue
• Change requires CSR request JDK-8369347 to be approved

Issues

• JDK-8369346: Remove default value of and deprecate the MaxRAM flag (Enhancement - P4)
• JDK-8369347: Remove default value of and deprecate the MaxRAM flag (CSR)

Reviewers

• Albert Mingkun Yang (@albertnetymk - Reviewer)

Reviewing

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

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8369346: Remove default value of and deprecate the MaxRAM flag

Reviewed-by: ayang

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At the time when this comment was updated there had been 2 new commits pushed to the master branch:

• da968dc: 8370227: Migrate micros-javac benchmarks from jmh-jdk-microbenchmarks
• aec1388: 8313770: jdk/internal/platform/docker/TestSystemMetrics.java fails on Ubuntu

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