RFR: JDK-8318016: Per-compilation memory ceiling [v3]
Thomas Stuefe
stuefe at openjdk.org
Fri Oct 27 12:57:07 UTC 2023
> This RFE introduces a new compile command to limit memory usage per compilation. It complements and is based upon the JIT memory statistic introduced with https://bugs.openjdk.org/browse/JDK-8317683.
>
> This new memory limit is applied during compilation for either C1 or C2. It has one of two modes:
> - *crash* mode (mainly for compiler devs), which aborts with hs-err file when the ceiling is reached, right in the compiler thread at the allocation point that triggered the ceiling
> - *stop* mode, which stops the compilation similarly to how hitting the node limit in C2 would stop the compilation.
>
> #### Usage
>
> The compile command takes the form `-XX:CompileCommand:MemLimit,<method>,<memory size>[~<option>]`
>
> The memory size that can be specified as usual. The command also takes an optional trailing option, separated from the memory size by a tilde (odd choice but needed because of https://bugs.openjdk.org/browse/JDK-8318214).
>
> The `<suboption>` can be either `crash` or `stop` and distinguishes between the aforementioned modes. If omitted, the default is "stop".
>
> Since `MemLimit` is based on the JIT statistic, it is implicitly enabled, so there is no need to explicitly enable it with `MemStat`.
>
>
> Usage examples:
>
>
> - crash when reaching 100m for a single compilation:
>
>
> -XX:CompileCommand='MemLimit,*.*,100m~crash'
>
>
> - limit all methods to a 2m footprint and print a trailing record at VM shutdown
>
>
> -XX:CompileCommand='MemLimit,*.*,2m' -XX:CompileCommand='MemStat,*.*,print'
>
>
> The JIT statistic table (printed either at VM shutdown or via `jcmd <pid> Compiler.memory`) now has a new column "result" that shows if the compilation was completed successfully or had an error or an oom:
>
>
> vvvvv
> total NA RA result #nodes time type #rc thread method
> 3036016 687328 1757456 oom 2607 0,320 c2 1 0x00007fcf1c181550 java/lang/invoke/StringConcatFactory::<clinit>(()V)
>
>
>
> #### Implementation notes
>
> The crash variant works immediately.
>
> The stop variant works delayed: If arena memory reaches the limit in the scope of a compilation, we signal the Compile object (`Compile` for c2, `Compilation` for c1) that an oom has occurred.
>
> For C1, we set the bailout string rig...
Thomas Stuefe has updated the pull request incrementally with one additional commit since the last revision:
fix typo
-------------
Changes:
- all: https://git.openjdk.org/jdk/pull/16220/files
- new: https://git.openjdk.org/jdk/pull/16220/files/8e0ab821..55e12f68
Webrevs:
- full: https://webrevs.openjdk.org/?repo=jdk&pr=16220&range=02
- incr: https://webrevs.openjdk.org/?repo=jdk&pr=16220&range=01-02
Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
Patch: https://git.openjdk.org/jdk/pull/16220.diff
Fetch: git fetch https://git.openjdk.org/jdk.git pull/16220/head:pull/16220
PR: https://git.openjdk.org/jdk/pull/16220
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