RFR: 8374875: Improve perfMemory warning about 'Insufficient space for shared memory file'

[Matthias Baesken]

On Fri, 9 Jan 2026 12:29:14 GMT, Matthias Baesken <mbaesken at openjdk.org> wrote:

> We have a perfMemory warning about 'Insufficient space for shared memory file'; this currently prints misleading info about 'java.io.tmpdir' and misses to print the directory, so we get no clue where exactly insufficient space is.
> 
> 
> Current Example output :
> OpenJDK 64-Bit Server VM warning: Insufficient space for shared memory file:
>    31671
> Try using the -Djava.io.tmpdir= option to select an alternate temp location.
> 
> 
> Just printing '31671' does not really help me much.
> And the suggestion to set  `java.io.tmpdir ` seems to be wrong; it WAS set in the java - execution the output is from, but is not used in the perfMemory coding  (probably intentionally).

Btw. when looking at
https://github.com/openjdk/jdk/blob/c8c6e7007aec9a568c25dcd5d4242b7911a83bfe/src/hotspot/share/cds/filemap.cpp#L1059-L1062
in case of a write failure, we remove the potentially broken/incomplete file.
Should we do this here as well to avoid leftover files ?

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PR Comment: https://git.openjdk.org/jdk/pull/29138#issuecomment-3728735826