RFR: 8368668: Several vmTestbase/vm/gc/compact tests timed out on large memory machine

[SendaoYan]

On Thu, 25 Sep 2025 15:07:29 GMT, Leonid Mesnik <lmesnik at openjdk.org> wrote:

> We run them concurrently

The file such as test/hotspot/jtreg/vmTestbase/vm/gc/compact/Compact_InternedStrings/TEST.properties which contain config `exclusiveAccess.dirs=.` will make sure these tests run serial, jtreg will ignore the '-conc' parameter when run these tests.

> If you execute test with some specific configuration

My test command is 'jtreg -v:fail,error,time -timeout:10 -nr -w tmp test/hotspot/jtreg/vmTestbase/vm/gc/compact/Compact_InternedStrings_Strings/TestDescription.java', there is no specific configuration. I think the biggest difference maybe my machine has huge physical memory, and many cpu core number.

The test log shows this test will run finish 250 seconds on my machine, seems that the test will detect all the available memory automaticly and the huge memory will consume lots of time to finish. On my machine this test use 448 threads and 30GB max memory to test. So I want to limit the memory usage in test by jvm option `-Xmx2G`.

The partial log snippet from vmTestbase/vm/gc/compact/Compact_InternedStrings_Strings/TestDescription.jtr
Max memory: 32178700288
Sleep time: 500
Iterations: 0
Number of threads: 448

[TestDescription.jtr.log](https://github.com/user-attachments/files/22551569/TestDescription.jtr.log)

After add the `-Xmx2G`, the test will detect use 64 threads and 2GB max memory to test. Another solution maybe use test parameter -t 16 to limit the test thread.


The test environmental info:
$ lscpu | head -n 8
Architecture:                    x86_64
CPU op-mode(s):                  32-bit, 64-bit
Address sizes:                   52 bits physical, 57 bits virtual
Byte Order:                      Little Endian
CPU(s):                          224
On-line CPU(s) list:             0-223
Vendor ID:                       GenuineIntel
Model name:                      Intel(R) Xeon(R) Platinum 8480+
$ free -h
               total        used        free      shared  buff/cache   available
Mem:           755Gi       8.6Gi       720Gi       4.0Mi        26Gi       742Gi
Swap:          8.0Gi        18Mi       8.0Gi

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PR Review Comment: https://git.openjdk.org/jdk/pull/27488#discussion_r2380733991