Add content for JEP 331

OpenJ9 now provides an implementation of JEP 331, which enables heap profiling with minimal resources. There are a couple of restrictions, which are documented. Closes: #284 Signed-off-by: Sue Chaplain <[email protected]>
eclipse-openj9 · Jul 3, 2019 · cc077e0 · cc077e0
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commit cc077e0
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diff --git a/docs/version0.15.md b/docs/version0.15.md
@@ -33,6 +33,7 @@
 - ![Start of content that applies only to Java 11 (LTS)](cr/java11.png) [ChaCha20 algorithm support for OpenSSL](#chacha20-algorithm-support-for-openssl)![End of content that applies only to Java 11 (LTS)](cr/java_close_lts.png)
 - [Support for OpenJDK HotSpot options](#support-for-openjdk-hotspot-options)
 - [Support for Transparent HugePage](#support-for-transparent-hugepage)
+-  ![Start of content that applies to Java 11 (LTS) and later](cr/java11plus.png) [Support for low-overhead heap profiling (JEP 331)](#support-for-low-overhead-heap-profiling)![End of content that applies only to Java 11 (LTS)](cr/java_close_lts.png)
 - [Removal of -Xdiagnosticscollector option](#removal-of-xdiagnosticscollector-option)
 
 
@@ -69,6 +70,16 @@ For compatibility, the [`-XX:OnOutOfMemoryError`](xxonoutofmemoryerror.md) OpenJ
 
 The VM now supports the allocation of huge pages on Linux when you use the `madvise` (`/sys/kernel/mm/transparent_hugepage/enabled`) setting. To enable this feature, set [`-XX:+TransparentHugePage`](xxtransparenthugepage.md) on the command line when you start your application. This option is currently not enabled by default.
 
+###  ![Start of content that applies to Java 11 (LTS) and later](cr/java11plus.png) Support for low-overhead heap profiling
+
+[JEP 331](http://openjdk.java.net/jeps/331) provides a mechanism for sampling Java heap allocations with a low overhead via
+the JVM Tool Interface (JVMTI).
+
+<i class="fa fa-exclamation-triangle" aria-hidden="true"></i> **Restrictions:** JEP 331 is implemented for OpenJ9 with the following limitations:
+
+- The `balanced` and `metronome` garbage collection policies are not supported.
+- The changes might not be compatible with the Health Center agent, which uses the same sampling interval.
+
 ### Removal of -Xdiagnosticscollector option
 This option was redundant and has now been removed. If you try to use this option on the command line, the VM outputs this error message: