RFR: 8354057: Odd debug output in -Xlog:os+container=debug on certain systems

[Ashutosh Mehra]

On Wed, 9 Apr 2025 02:05:15 GMT, Thomas Fitzsimmons <duke at openjdk.org> wrote:

> The issue was a trailing newline in a message argument to:
> 
> 
> log_debug(os, container)(...)
> 
> 
> `log_debug` implicitly appends a newline to the message, so the extra newline resulted in empty lines in the trace output.
> 
> The old vs new output on my `Alpine Linux v3.21` virtual machine is:
> 
> 
> --- tt-old-alpine-legacy.txt	2025-04-08 21:49:31.847415499 -0400
> +++ tt-new-alpine-legacy.txt	2025-04-08 21:48:51.486322068 -0400
> @@ -1,10 +1,8 @@
>  [0.000s][trace][os,container] OSContainer::init: Initializing Container Support
>  [0.000s][debug][os,container] Detected optional pids controller entry in /proc/cgroups
>  [0.000s][debug][os,container] controller cpuset is not enabled
> -[                           ] 
>  [0.000s][debug][os,container] controller memory is not enabled
> -[                           ] 
>  [0.000s][debug][os,container] One or more required controllers disabled at kernel level.
>  openjdk version "25-internal" 2025-09-16
> -OpenJDK Runtime Environment (fastdebug build 25-internal-adhoc.fitzsim.jdk-old)
> -OpenJDK 64-Bit Server VM (fastdebug build 25-internal-adhoc.fitzsim.jdk-old, mixed mode)
> +OpenJDK Runtime Environment (fastdebug build 25-internal-adhoc.fitzsim.jdk)
> +OpenJDK 64-Bit Server VM (fastdebug build 25-internal-adhoc.fitzsim.jdk, mixed mode)
> 
> 
> Regression-tested with:
> 
> 
> make exploded-test TEST="test/hotspot/jtreg/containers test/jdk/jdk/internal/platform/cgroup gtest:cgroupTest*"

looks good!

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

Marked as reviewed by asmehra (Committer).

PR Review: https://git.openjdk.org/jdk/pull/24533#pullrequestreview-2754220837