On Tue, 23 Dec 2025 20:07:36 GMT, Kieran Farrell <[email protected]> wrote:
>> Currently, it is only possible to read the number of open file descriptors >> of a Java process via the `UnixOperatingSystemMXBean` which is only >> accessible via JMX enabled tools. To improve servicability, it would be >> benifical to be able to view this information from jcmd VM.info output or >> hs_err_pid crash logs. This could help diagnose resource exhaustion and >> troubleshoot "too many open files" errors in Java processes on Unix >> platforms. >> >> This PR adds reporting the current open file descriptor count to both jcmd >> VM.info output or hs_err_pid crash logs by refactoring the native JNI logic >> from >> `Java_com_sun_management_internal_OperatingSystemImpl_getOpenFileDescriptorCount0` >> of the `UnixOperatingSystemMXBean` into hotspot. Apple's API for retrieving >> open file descriptor count provides an array of the actual FDs to determine >> the count. To avoid using `malloc` to store this array in a potential signal >> handling context where stack space may be limited, the apple implementation >> instead allocates a fixed 32KB struct on the stack to store the open FDs and >> only reports the result if the struct is less than the max (1024 FDs). This >> should cover the majoirty of use cases. > > Kieran Farrell has updated the pull request incrementally with one additional > commit since the last revision: > > comment 50ms timed loop added to limit the proc file read for the AIX and linux implementations. ------------- PR Comment: https://git.openjdk.org/jdk/pull/27971#issuecomment-3687847914
