On Thu, 9 Jul 2026 12:30:43 GMT, Coleen Phillimore <[email protected]> wrote:

>> Please review this change to allow XX configuration for specifying a 
>> different /tmp directory for the JVM to use.  In some container 
>> environments, /tmp and /proc/pid/root/tmp might not be usable and an 
>> alternate would be used.  This requires a release note and CSR.   Usage is:
>> 
>> java -XX:AltTempDir=/diags <app>
>> jps -J-XX:AltTempDir=/diags
>> jcmd -J-XX:AltTempDir=/diags <pid> <cmds>
>> 
>> Tested with a couple of tests and locally, and ran tier1-4.
>> 
>> ---------
>> - [x] I confirm that I make this contribution in accordance with the 
>> [OpenJDK Interim AI Policy](https://openjdk.org/legal/ai).
>
> Coleen Phillimore has updated the pull request incrementally with one 
> additional commit since the last revision:
> 
>   Moved down AltTempDir in jinfo.md

src/hotspot/os/linux/os_linux.cpp line 1562:

> 1560: // Since the attach mechanism uses the socket name length, this 
> severely limits the length of the
> 1561: // alternate temporary directory name.  We don't check that here since 
> the temporary directory is
> 1562: // used for many things. The perfData and attach code will check it.

Nit: I can't fully understand the comment at lines 1557-1562.
Are we trying to say this:
 - absolute paths are enforced
 - existence and writeability is warned but not rejected ?
Is it possible to simplify the wording a little bit to make it more clear?

src/jdk.attach/linux/native/libattach/VirtualMachineImpl.c line 80:

> 78:         addr.sun_family = AF_UNIX;
> 79:         if (strlen(p) >= sizeof(addr.sun_path)) {
> 80:             JNU_ThrowIOException(env, "Socket file path too long");

Nit:
The exception is thrown without releasing the string `p`.
This does not match the comment at lines 95-97.

src/jdk.internal.jvmstat/linux/classes/sun/jvmstat/PlatformSupportImpl.java 
line 175:

> 173:     /*
> 174:      * Extract the VM ID (PID) from a file path.
> 175:      * Specifically the host pid for a container process.

Nit: Inconsistency with use of `PID` and `pid`. Better to have the same naming 
style to avoid confusions.

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/31407#discussion_r3557042477
PR Review Comment: https://git.openjdk.org/jdk/pull/31407#discussion_r3556973760
PR Review Comment: https://git.openjdk.org/jdk/pull/31407#discussion_r3556988351

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