RFR: JDK-8318016: Per-compilation memory ceiling [v3]
Tobias Hartmann
thartmann at openjdk.org
Wed Nov 1 06:22:01 UTC 2023
On Fri, 27 Oct 2023 12:57:07 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:
>> 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` fo...
>
> Thomas Stuefe has updated the pull request incrementally with one additional commit since the last revision:
>
> fix typo
All tests passed.
-------------
PR Comment: https://git.openjdk.org/jdk/pull/16220#issuecomment-1788472025
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