From a0e012b6e0ae59476d51dd959f0768ecf110ffea Mon Sep 17 00:00:00 2001
From: Jarek Gawor <jgawor@gmail.com>
Date: Sat, 17 Oct 2015 00:22:34 -0400
Subject: [PATCH] configure heap size ratio

---
 config/ibmjdk.yml                         |  2 ++
 docs/ibm-jdk.md                           | 17 +++++++++++++++++
 lib/liberty_buildpack/jre/ibmjdk.rb       | 16 ++++++++--------
 spec/liberty_buildpack/jre/ibmjdk_spec.rb | 23 +++++++++++++++++++++--
 4 files changed, 48 insertions(+), 10 deletions(-)

diff --git a/config/ibmjdk.yml b/config/ibmjdk.yml
index 7399d46c8..ddad9fc30 100644
--- a/config/ibmjdk.yml
+++ b/config/ibmjdk.yml
@@ -17,3 +17,5 @@
 ---
 repository_root: "https://public.dhe.ibm.com/ibmdl/export/pub/software/websphere/wasdev/downloads/jre"
 version: 1.8.+
+
+heap_size_ratio: 0.75
diff --git a/docs/ibm-jdk.md b/docs/ibm-jdk.md
index 6caa79efc..5f408b24c 100644
--- a/docs/ibm-jdk.md
+++ b/docs/ibm-jdk.md
@@ -17,6 +17,23 @@ The JRE can be configured by modifying the [`config/ibmjdk.yml`][] file in the b
 | ---- | -----------
 | `repository_root` | The URL of the IBM JRE repository index ([details][repositories]).
 | `version` | The version of Java runtime to use.  Candidate versions can be found [here][index.yml].
+| `heap_size_ratio` | The ratio that is used to calculate the maximum heap size. The default heap size ratio is `0.75` (75% of the total available memory).
+
+## Common Configuration Overrides
+
+The IBM JRE [configuration can be overridden](configuration.md) with the `JBP_CONFIG_IBMJDK` environment variable. The value of the variable should be valid inline YAML. For example:
+
+1. Adjust heap size ratio:
+
+   ```bash
+   $ cf set-env myApplication JBP_CONFIG_IBMJDK 'heap_size_ratio: 0.90'
+   ```
+
+1. Use IBM JRE version 7:
+
+   ```bash
+   $ cf set-env myApplication JBP_CONFIG_IBMJDK 'version: 1.7.+'
+   ```
 
 [`config/ibmjdk.yml`]: ../config/ibmjdk.yml
 [index.yml]: http://public.dhe.ibm.com/ibmdl/export/pub/software/websphere/wasdev/downloads/jre/index.yml
diff --git a/lib/liberty_buildpack/jre/ibmjdk.rb b/lib/liberty_buildpack/jre/ibmjdk.rb
index acde1c44c..987cb2da5 100644
--- a/lib/liberty_buildpack/jre/ibmjdk.rb
+++ b/lib/liberty_buildpack/jre/ibmjdk.rb
@@ -165,25 +165,25 @@ def java_home
     end
 
     def memory(configuration)
+      java_memory_opts = []
+      java_memory_opts.push '-Xtune:virtualized'
+
       mem = MemoryLimit.memory_limit
       if mem.nil?
         ## if no memory option has been set by cloudfoundry, we just assume defaults
-        java_memory_opts = []
-        java_memory_opts.push '-Xtune:virtualized'
-
         java_memory_opts
       else
-        java_memory_opts = []
-
-        new_heap_size = mem * HEAP_SIZE_RATIO
-
-        java_memory_opts.push '-Xtune:virtualized'
+        new_heap_size = mem * heap_size_ratio
         java_memory_opts.push "-Xmx#{new_heap_size}"
 
         java_memory_opts
       end
     end
 
+    def heap_size_ratio
+      @configuration['heap_size_ratio'] || HEAP_SIZE_RATIO
+    end
+
     # default options for -Xdump to disable dumps while routing to the default dumps location when it is enabled by the
     # user
     def default_dump_opts
diff --git a/spec/liberty_buildpack/jre/ibmjdk_spec.rb b/spec/liberty_buildpack/jre/ibmjdk_spec.rb
index 2ef0e388d..f640202a3 100644
--- a/spec/liberty_buildpack/jre/ibmjdk_spec.rb
+++ b/spec/liberty_buildpack/jre/ibmjdk_spec.rb
@@ -164,16 +164,35 @@ module LibertyBuildpack::Jre
                                       '-Xdump:heap+java+snap:events=user')
         end
 
-        it 'should add extra memory options when a memory limit is set' do
+        it 'should add extra memory options when 512m memory limit is set' do
           ENV['MEMORY_LIMIT'] = '512m'
 
           expect(released).to include('-Xtune:virtualized')
           expect(released).to include('-Xmx384M')
         end
 
-        it 'should provide troubleshooting info for JVM shutdowns' do
+        it 'should add extra memory options when 512m memory limit is set with 50% ratio', configuration: { 'heap_size_ratio' => 0.50 } do
           ENV['MEMORY_LIMIT'] = '512m'
 
+          expect(released).to include('-Xtune:virtualized')
+          expect(released).to include('-Xmx256M')
+        end
+
+        it 'should add extra memory options when 1024m memory limit is set' do
+          ENV['MEMORY_LIMIT'] = '1024m'
+
+          expect(released).to include('-Xtune:virtualized')
+          expect(released).to include('-Xmx768M')
+        end
+
+        it 'should add extra memory options when 1024m memory limit is set with 12.% ratio', configuration: { 'heap_size_ratio' => 0.125 }  do
+          ENV['MEMORY_LIMIT'] = '1024m'
+
+          expect(released).to include('-Xtune:virtualized')
+          expect(released).to include('-Xmx128M')
+        end
+
+        it 'should provide troubleshooting info for JVM shutdowns' do
           expect(released).to include("-Xdump:tool:events=systhrow,filter=java/lang/OutOfMemoryError,request=serial+exclusive,exec=./#{LibertyBuildpack::Diagnostics::DIAGNOSTICS_DIRECTORY}/#{IBMJdk::KILLJAVA_FILE_NAME}")
         end
       end # end of release shared tests