[8u] RFR (XS) 8231398: Add time tracing for gc log rotation at safepoint cleanup

[Hohensee, Paul]

Looks good.

Paul

On 9/24/19, 1:17 AM, "hotspot-runtime-dev on behalf of Aleksey Shipilev" <hotspot-runtime-dev-bounces at openjdk.java.net on behalf of shade at redhat.com> wrote:

    RFE:
      https://bugs.openjdk.java.net/browse/JDK-8231398
    
    There is a nice gotcha when dealing with low latency workloads. The safepoint cleanup does lots of
    things, notably rotating the GC logs in 8 (fixed by transition to Unified Logging in 9+, see
    JDK-8145092). Those things are normally caught by -XX:+TraceSafepointCleanupTime, but not gc log
    rotation, since it misses the tracing statement.
    
    We should consider adding the tracing there.
    
    Webrev:
      https://cr.openjdk.java.net/~shade/8231398/webrev.01/
    
    Testing: eyeballing safepoint cleanup tracing, tier1 (running)
    
    -- 
    Thanks,
    -Aleksey