RFR: 8308094: Add a compilation timeout flag to catch long running compilations [v11]

[Dean Long]

On Tue, 19 Aug 2025 14:36:05 GMT, Manuel Hässig <mhaessig at openjdk.org> wrote:

>> This PR adds `-XX:CompileTaskTimeout` on Linux to limit the amount of time a compilation task can run. The goal of this is initially to be able to find and investigate long-running compilations.
>> 
>> The timeout is implemented using a POSIX timer that sends a `SIGALRM` to the compiler thread the compile task is running on. Each compiler thread registers a signal handler that triggers an assert upon receiving `SIGALRM`. This is currently only implemented for Linux, because it relies on `SIGEV_THREAD_ID` to get the signal delivered to the same thread that timed out.
>> 
>> Since `SIGALRM` is now used, the test `runtime/signal/TestSigalrm.java` now requires `vm.flagless` so it will not interfere with the compiler thread signal handlers.
>> 
>> Testing:
>>  - [x] Github Actions
>>  - [x] tier1, tier2 on all platforms
>>  - [x] tier3, tier4 and Oracle internal testing on Linux fastdebug
>>  - [x] tier1 through tier4 with `-XX:CompileTaskTimeout=60000` (one minute timeout) to see what fails (`compiler/codegen/TestAntiDependenciesHighMemUsage2.java`, `compiler/loopopts/TestMaxLoopOptsCountReached.java`, and `compiler/c2/TestScalarReplacementMaxLiveNodes.java` fail)
>
> Manuel Hässig has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - Print timeout properly
>  - Use static buffer for method name

src/hotspot/os/linux/compilerThreadTimeout_linux.cpp line 47:

> 45:       char method_name_buf[SIZE];
> 46:       task->method()->name_and_sig_as_C_string(method_name_buf, SIZE);
> 47:       assert(false, "compile task %d (%s) timed out after " INTX_FORMAT " ms",

Can we use %zd here?  INTX_FORMAT was removed in JDK-8346990.

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PR Review Comment: https://git.openjdk.org/jdk/pull/26023#discussion_r2285791418