On Wed, 8 Jul 2026 11:27:50 GMT, Kevin Walls <[email protected]> wrote:
>> src/jdk.internal.jvmstat/linux/classes/sun/jvmstat/PlatformSupportImpl.java
>> line 207:
>>
>>> 205: seenProc = true;
>>> 206: continue;
>>> 207: }
>>
>> Q1: How would the above work if the TMP directory was set/customized with
>> the option:
>> `-XX:AltTempDir=/work/proc/tmp` ? What happens if there are multiple `proc`
>> path folders?
>
> I thought I had suggested a fairly naive getLocalVmId(File) in
> PlatformSupportImpl.java, but it does handle extra "proc" elements.
> It needs to parse directories like:
> /proc/{pid}/root/tmp/hsperfdata_{user}/{nspid}
>
> -XX:AltTempDir=/tmp/proc/scratch does not fool it, as it will be parsing
> /proc/PID/tmp/proc/scratch/...
>
> ..and only looks at PID after the first "proc". Subsequent "proc" elements
> mean nothing.
>
> What does fool it, is AltTempDir=/tmp/x/hsperfdata_kwalls/foo
> ..where it assumes hsperfdata_ in a path element is followed by a pid/nspid.
>
> We can handle the Integer parsing, and continue to the next path element.
>
> But that means it's a problem if using
> AltTempDir=/tmp/x/hsperfdata_kwalls/foo/123
> So, remove the "break" and always count the last pid/nspid we see.
>
> @coleenp This update works with these crazier AltTempDir settings:
>
> "src/jdk.internal.jvmstat/linux/classes/sun/jvmstat/PlatformSupportImpl.java"
> line 217
> if (seenPerf) {
> // Parse pid or nspid after seeing "hsperfdata_"
> try {
> if (hostpid == -1) {
> hostpid = Integer.parseInt(s);
> } else {
> nspid = Integer.parseInt(s);
> }
> } catch (NumberFormatException _) {
> // e.g. Extra "hsperfdata_" found in path from AltTempDir.
> }
> }
I added this change but not sure how this parsing should work. If the first
thing is /proc, we throw NumberFormatException if the second thing isn't a
number. What about AltTempDir=/proc/proc/proc ? In a container is this
/proc/<pid>/root/proc/proc/proc/hsperfdata_user/pid ?
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/31407#discussion_r3543936652
