RFR: 8339487: ProcessHandleImpl native exceptions - include message text and last error information [v2]

[Alan Bateman]

On Thu, 5 Sep 2024 13:20:11 GMT, Matthias Baesken <mbaesken at openjdk.org> wrote:

>> When running jtreg test java/lang/ProcessHandle/PermissionTest.java on macOS, a few times this error occurs :
>> 
>> java.lang.RuntimeException: Cannot allocate memory
>>        at java.base/java.lang.ProcessHandleImpl.getProcessPids0(Native Method)
>>        at java.base/java.lang.ProcessHandleImpl.children(ProcessHandleImpl.java:456)
>>        at java.base/java.lang.ProcessHandleImpl.children(ProcessHandleImpl.java:434)
>>        at PermissionTest.childrenWithPermission(PermissionTest.java:84)
>>        at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
>>        at java.base/java.lang.reflect.Method.invoke(Method.java:573)
>>        at org.testng.internal.MethodInvocationHelper.invokeMethod(MethodInvocationHelper.java:132)
>>        at org.testng.internal.TestInvoker.invokeMethod(TestInvoker.java:599)
>>        at org.testng.internal.TestInvoker.invokeTestMethod(TestInvoker.java:174)
>>        at org.testng.internal.MethodRunner.runInSequence(MethodRunner.java:46)
>>        at org.testng.internal.TestInvoker$MethodInvocationAgent.invoke(TestInvoker.java:822)
>>        at org.testng.internal.TestInvoker.invokeTestMethods(TestInvoker.java:147)
>>        at org.testng.internal.TestMethodWorker.invokeTestMethods(TestMethodWorker.java:146)
>>        at org.testng.internal.TestMethodWorker.run(TestMethodWorker.java:128)
>>        at java.base/java.util.ArrayList.forEach(ArrayList.java:1597)
>> 
>> 
>> Probably sysctl fails here, but it is not fully clear; it would help to change the exception so that the standard text is shown too in the exception message.
>
> Matthias Baesken has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Repeat sysctl in case of failures;  increase the proc info buffer a bit to hold some more very recent procs

src/java.base/macosx/native/libjava/ProcessHandleImpl_macosx.c line 124:

> 122:         // Read process info for all processes
> 123:         errsysctl = sysctl(mib, 4, buffer, &bufSize, NULL, 0);
> 124:     } while (errsysctl < 0 && maxRetries-- > 0);

Using a loop is good but I assume only when the second sysctl fails with errno=ENOMEM.

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PR Review Comment: https://git.openjdk.org/jdk/pull/20839#discussion_r1746012053