test/hotspot/jtreg/gc/z/TestHighUsage.java

*** 72,81 ****
--- 72,89 ----
                  if (free > spikeAt) {
                      // Low allocation rate
                      dummy = new byte[128 * K];
                  } else {
                      // High allocation rate
+ 
+                     // Before inducing an allocation spike, give the GC time to
+                     // complete a cycle. This is needed in case the test system
+                     // is starved on CPU, in which case the GC might not otherwise
+                     // be able to complete a cycle before the allocation spike
+                     // happens, resulting in an allocation stall.
+                     Thread.sleep(50000);
+ 
                      dummy = new byte[8 * M];
                  }
  
                  Thread.sleep(250);
              }
*** 91,101 ****
                                                    "-XX:-ZProactive",
                                                    "-Xms128M",
                                                    "-Xmx128M",
                                                    "-XX:ParallelGCThreads=1",
                                                    "-XX:ConcGCThreads=1",
!                                                   "-Xlog:gc",
                                                    Test.class.getName() })
                      .shouldNotContain("Allocation Stall")
                      .shouldContain("High Usage")
                      .shouldHaveExitValue(0);
      }
--- 99,109 ----
                                                    "-XX:-ZProactive",
                                                    "-Xms128M",
                                                    "-Xmx128M",
                                                    "-XX:ParallelGCThreads=1",
                                                    "-XX:ConcGCThreads=1",
!                                                   "-Xlog:gc,gc+start",
                                                    Test.class.getName() })
                      .shouldNotContain("Allocation Stall")
                      .shouldContain("High Usage")
                      .shouldHaveExitValue(0);
      }