RFR: [XS] 8229284: [TESTBUG] jdk/internal/platform/cgroup/TestCgroupMetrics.java fails for - memory:getMemoryUsage

[Baesken, Matthias]

> Should you continue waiting in the loop until BOTH the new usage and max
> usage exceed their  initial values?


Hi Bob,  the  current coding  does not do it .  It checks  for  "<"  to fail .
Please see the current coding :

 583         long memoryMaxUsage = metrics.getMemoryMaxUsage();
 584         long memoryUsage = metrics.getMemoryUsage();

 586         byte[] bb = new byte[64*1024*1024]; // 64M
 587 
 588         long newMemoryMaxUsage = metrics.getMemoryMaxUsage();
 589         long newMemoryUsage = metrics.getMemoryUsage();

 590 
 591         if(newMemoryMaxUsage < memoryMaxUsage) {
 592             fail(SubSystem.MEMORY, "getMemoryMaxUsage", newMemoryMaxUsage,
 593                     memoryMaxUsage);
 594         }
 595 
 596         if(newMemoryUsage < memoryUsage) {
 597             fail(SubSystem.MEMORY, "getMemoryUsage", newMemoryUsage, memoryUsage);
 598         }
 599     }

My  change does not intend  to change this logic ,  just does more allocations to make sure the  current check works .


Best regards, Matthias



> -----Original Message-----
> From: Bob Vandette <bob.vandette at oracle.com>
> Sent: Mittwoch, 28. August 2019 15:24
> To: Baesken, Matthias <matthias.baesken at sap.com>
> Cc: Severin Gehwolf <sgehwolf at redhat.com>; hotspot-
> dev at openjdk.java.net
> Subject: Re: RFR: [XS] 8229284: [TESTBUG]
> jdk/internal/platform/cgroup/TestCgroupMetrics.java fails for -
> memory:getMemoryUsage
> 
> Should you continue waiting in the loop until BOTH the new usage and max
> usage exceed their
> initial values?
> 
> Bob.
> 
> 
> > On Aug 28, 2019, at 8:39 AM, Baesken, Matthias
> <matthias.baesken at sap.com> wrote:
> >
> > Hi Severin, I changed  the  fail() - calls   and the  newMemoryMaxUsage
> handling.
> > New webrev :
> >
> > http://cr.openjdk.java.net/~mbaesken/webrevs/8229284.5/
> >
> >
> > Best regards, Matthias
> >
> >
> >>
> >> On Thu, 2019-08-15 at 16:08 +0000, Baesken, Matthias wrote:
> >>> https://bugs.openjdk.java.net/browse/JDK-8229284
> >>>
> >>> http://cr.openjdk.java.net/~mbaesken/webrevs/8229284.3/
> >>
> >> Hmm, unrelated to this bug, but still an issue:
> >>
> >> It appears the failure message is bogus when the test fails. It should
> >> be:
> >>
> >> java.lang.RuntimeException: Test failed for - memory:getMemoryUsage,
> >> expected [56200986624], got [56019386368]
> >>
> >> I.e. the old/new values need to be swapped here:
> >>
> >> 597             fail(SubSystem.MEMORY, "getMemoryUsage",
> >> newMemoryUsage, memoryUsage);
> >>
> >> Same for the getMemoryMaxUsage() fail:
> >>
> >> 592             fail(SubSystem.MEMORY, "getMemoryMaxUsage",
> >> newMemoryMaxUsage,
> >> 593                     memoryMaxUsage);
> >>
> >> As to the bug. It suggests the memoryUsage code causes problems, not
> >> memoryMaxUsage.
> >>
> >> 587         // allocate memory in a loop and check more than once for new
> >> values
> >> 588         // otherwise we might see seldom the effect of decreasing new
> >> memory values
> >> 589         // e.g. because the system could free up memory
> >> 590         byte[][] bytes = new byte[32][];
> >> 591         for (int i = 0; i < 32; i++) {
> >> 592             bytes[i] = new byte[8*1024*1024];
> >> 593             newMemoryMaxUsage = metrics.getMemoryMaxUsage();
> >> 594             newMemoryUsage = metrics.getMemoryUsage();
> >> 595             if (newMemoryMaxUsage > memoryMaxUsage &&
> >> newMemoryUsage > memoryUsage) {
> >> 596                 break;
> >> 597             }
> >>
> >> Do we really need to call metrics.getMemoryMaxUsage() in that loop? I'd
> >> expect for the following code to work more reliably as the max usage is
> >> supposed to capture the high water mark. If memoryMaxUsage ever
> >> decreases, it's a bug in the cgroups accounting system right?
> >>
> >> byte[][] bytes = new byte[32][];
> >> for (int i = 0; i < 32; i++) {
> >>    bytes[i] = new byte[8*1024*1024];
> >>    newMemoryUsage = metrics.getMemoryUsage();
> >>    if (newMemoryUsage > memoryUsage) {
> >>        break;
> >>    }
> >> }
> >> newMemoryMaxUsage = metrics.getMemoryMaxUsage();
> >>
> >> // assert things
> >>
> >> Perhaps even assert prior the loop:
> >>
> >> if (memoryMaxUsage < memoryUsage) {
> >>    throw new RuntimeException("cgroup accounting bug?");
> >> }
> >>
> >> Thanks,
> >> Severin
> >