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

[Thomas Fitzsimmons]

On Wed, 9 Apr 2025 16:37:24 GMT, Severin Gehwolf <sgehwolf 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*"
>
> Marked as reviewed by sgehwolf (Reviewer).

Thank you for reviewing, @jerboaa, @ashu-mehra and @lmesnik.  Can one of you please sponsor this change?

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PR Comment: https://git.openjdk.org/jdk/pull/24533#issuecomment-2790603361