RFR: TestSelectiveBarrierFlags times out due to too aggressive compilation mode

[Aleksey Shipilev]

TestSelectiveBarrierFlags uses "-Xcomp" to make sure we actually reach compiler paths during "Hello
World" invocation. Unfortunately, that takes up to 3s for run. Using a more relaxed "-Xbatch
-XX:CompileThreshold=..." makes the test still reach the compilation path and improves test run time
around 10x. The improvement is because we don't compile overly cold methods, and test still works,
because we compile warmer ones.

Patch:

diff -r 90f120de8a35 -r e6ce6500a167 test/hotspot/jtreg/gc/shenandoah/TestSelectiveBarrierFlags.java
--- a/test/hotspot/jtreg/gc/shenandoah/TestSelectiveBarrierFlags.java	Thu Dec 14 12:02:33 2017 +0100
+++ b/test/hotspot/jtreg/gc/shenandoah/TestSelectiveBarrierFlags.java	Thu Dec 14 13:16:54 2017 +0100
@@ -26,8 +26,8 @@
  *          of barrier flags
  * @library /test/lib
  * @run main/othervm TestSelectiveBarrierFlags -Xint
- * @run main/othervm TestSelectiveBarrierFlags -Xcomp -XX:TieredStopAtLevel=1
- * @run main/othervm TestSelectiveBarrierFlags -Xcomp -XX:-TieredCompilation
-XX:+IgnoreUnrecognizedVMOptions -XX:+ShenandoahVerifyOptoBarriers
+ * @run main/othervm TestSelectiveBarrierFlags -Xbatch -XX:CompileThreshold=100 -XX:TieredStopAtLevel=1
+ * @run main/othervm TestSelectiveBarrierFlags -Xbatch -XX:CompileThreshold=100
-XX:-TieredCompilation -XX:+IgnoreUnrecognizedVMOptions -XX:+ShenandoahVerifyOptoBarriers
  */

 import java.util.*;


Testing: TestSelectiveBarrierFlags (fastdebug|release)

Thanks,
-Aleksey