[jdk21u-dev] RFR: 8337994: [REDO] Native memory leak when not recording any events

[Goetz Lindenmaier]

On Mon, 4 Nov 2024 17:28:07 GMT, Boris Ulasevich <bulasevich at openjdk.org> wrote:

>> (not a clean backport)
>> Reworked to avoid https://github.com/openjdk/jdk/pull/17328/files  backport
>> 
>> Functional jtreg1-3 tests are Ok.
>> Manual testing: the reproducer shows the problem is fixed with the change (see comments below)
>
> Reproducer:
> 
> import jdk.jfr.consumer.RecordingStream;
> 
> /**
>   * Stress test to provoke the memory leak:
>   * starts 1M empty threads in VM with jfr recording
>   */
> public class PinnedThreadTracker implements AutoCloseable
> {
>     private final RecordingStream recordingStream;
> 
>     public PinnedThreadTracker() {
>         recordingStream = new RecordingStream();
>         recordingStream.startAsync();
>         System.out.println("start recording..");
>     }
> 
>     @Override
>     public void close() {
>         recordingStream.close();
>     }
> 
>     class MyThread extends Thread {
>         public void run() {
>         }
>     }
>     public void runThreads() {
>         for (int i = 0; i < 100; i++) {
>             for (int j = 0; j < 100; j++) {
>                 for (int k = 0; k < 100; k++) {
>                     new MyThread().start();
>                 }
>                 MyThread thr = new MyThread(); thr.start();
>                 try {
>                     thr.join();
>                 } catch (Exception ex) {}
>             }
>             System.out.print(".");
>         }
>     }
> 
>     public static void main(String a[]) {
>         PinnedThreadTracker ptt = new PinnedThreadTracker();
>         ptt.runThreads();
>         ptt.close();
>     }
> }	
> 
> 
> Manual testing results on jdk21u:
> 
> $ for i in {0..60}; do
>     export PID=`ps -ax | grep java | grep PinnedThreadTracker | sed "s/^ *// ; s/ .*//"`
>     jcmd $PID VM.native_memory | grep Tracing.*reserved
>     sleep 1s
>   done
> 
> Before the change (jcmd VM.native_memory output once a second):
> -                   Tracing (reserved=17355KB, committed=17355KB)
> -                   Tracing (reserved=21646KB, committed=21646KB)
> -                   Tracing (reserved=25870KB, committed=25870KB)
> -                   Tracing (reserved=30065KB, committed=30065KB)
> ...
> -                   Tracing (reserved=240567KB, committed=240567KB)
> -                   Tracing (reserved=244519KB, committed=244519KB)
> -                   Tracing (reserved=248525KB, committed=248525KB)
> -                   Tracing (reserved=252527KB, committed=252527KB)
> 
> With the fix:
> -                   Tracing (reserved=17655KB, committed=17655KB)
> -                   Tracing (reserved=18125KB, committed=18125KB)
> -                   Tracing (reserved=18449KB, committed=18449KB)
> -                   Tracing (reserved=18961KB, committed=18961KB)
> ...
> -                   Tracing (reserved=17443KB, committed=17443KB)
> -                   Tracing (reserved=17958KB, committed=17958KB)
> -                   Tracing (reserved=...

Hi @bulasevich, can this wait for the April update? It would get some more test coverage.

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

PR Comment: https://git.openjdk.org/jdk21u-dev/pull/1095#issuecomment-2462229914