RFR: 8356277: containers/docker/TestPids.java: Limit value 19128 is not accepted as unlimited

[Severin Gehwolf]

On Tue, 6 May 2025 14:06:54 GMT, Jan Kratochvil <jkratochvil at openjdk.org> wrote:

> When running the testcase in a VM with 16GB RAM it fails as systemd limits DefaultTasksMax based on available RAM.
> 
> 
> test/hotspot/jtreg/containers/docker/TestPids.java
> TEST RESULT: Failed. Execution failed: `main' threw exception: java.lang.RuntimeException: Limit value 19128 is not accepted as unlimited, log line was [0.083s][trace][os,container] Maximum number of tasks is: 19128
> 
> 
> DefaultTasksMax=28776 for RAM 24576MB
> DefaultTasksMax=19128 for RAM 16384MB
> DefaultTasksMax=1088 for RAM 1024MB
> 
> The testcase expects DefaultTasksMax>=20000.

> > $ grep DefaultTasksMax /etc/systemd/system.conf
> > DefaultTasksMax = 31000
> 
> That does not work for me.
> 
> ```
> /usr/lib/systemd/system.conf:DefaultTasksMax=31000
> systemd-255.18-1.fc40.x86_64
> java.lang.RuntimeException: Limit value 19128 is not accepted as unlimited, log line was [0.096s][trace][os,container] Maximum number of tasks is: 19128
> ```

I think you need to do `sudo systemctl daemon-reload` for it to take effect (or reboot).
 
> Plus it is questionable why to require system reconfiguration when it can be fixed in the testsuite.

While that's true, AFAIK, it's only fixing the problem for `docker` and relies on `systemctl show` being present on the system, so it's not necessarily more universal.

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PR Comment: https://git.openjdk.org/jdk/pull/25067#issuecomment-2866665165