From 89a21c6a4667f02542e7889c23fef24461cdf236 Mon Sep 17 00:00:00 2001
From: Lari Hotari <lari@hotari.net>
Date: Tue, 21 Apr 2015 14:04:00 -0400
Subject: [PATCH] disable dynamic mmap threshold that leads to fragmentation -
 see M_MMAP_THRESHOLD in "man mallopt" -
 https://sourceware.org/bugzilla/show_bug.cgi?id=11044 - allow disabling
 tuning by setting JBP_NO_MALLOC_TUNING env

---
 .../component/base_component.rb               |  6 ++++
 spec/bin/release_spec.rb                      | 30 +++++++++++++++++++
 spec/integration_helper.rb                    |  1 +
 3 files changed, 37 insertions(+)

diff --git a/lib/java_buildpack/component/base_component.rb b/lib/java_buildpack/component/base_component.rb
index 8ae0963307..02b480459a 100644
--- a/lib/java_buildpack/component/base_component.rb
+++ b/lib/java_buildpack/component/base_component.rb
@@ -93,8 +93,14 @@ def command_environment
 
       # Resolve the environment that's passed on the command line
       def resolve_command_environment
+        return if ENV['JBP_NO_MALLOC_TUNING'] && ENV['JBP_NO_MALLOC_TUNING'] != '0'
         # set MALLOC_ARENA_MAX by default
         @default_command_environment['MALLOC_ARENA_MAX'] = 2 unless ENV.key? 'MALLOC_ARENA_MAX'
+        # disable dynamic mmap threshold, see M_MMAP_THRESHOLD in "man mallopt"
+        @default_command_environment['MALLOC_MMAP_THRESHOLD_'] = 131_072 unless ENV.key? 'MALLOC_MMAP_THRESHOLD_'
+        @default_command_environment['MALLOC_TRIM_THRESHOLD_'] = 131_072 unless ENV.key? 'MALLOC_TRIM_THRESHOLD_'
+        @default_command_environment['MALLOC_TOP_PAD_'] = 131_072 unless ENV.key? 'MALLOC_TOP_PAD_'
+        @default_command_environment['MALLOC_MMAP_MAX_'] = 65_536 unless ENV.key? 'MALLOC_MMAP_MAX_'
       end
 
       # Downloads an item with the given name and version from the given URI, then yields the resultant file to the
diff --git a/spec/bin/release_spec.rb b/spec/bin/release_spec.rb
index 23e9f8af91..dcfa6411cc 100644
--- a/spec/bin/release_spec.rb
+++ b/spec/bin/release_spec.rb
@@ -41,4 +41,34 @@
       expect(YAML.load(stdout.string)['default_process_types']['web']).to match(/^MALLOC_ARENA_MAX=2 .*/)
     end
   end
+
+  it 'allow disabling malloc tuning',
+     app_fixture: 'integration_valid' do
+
+    ENV['JBP_NO_MALLOC_TUNING'] = '1'
+    run("bin/release #{app_dir}") do |status|
+      expect(status).to be_success
+      expect(YAML.load(stdout.string)['default_process_types']['web']).not_to match(/^MALLOC_ARENA_MAX.*/)
+    end
+  end
+
+  it 'do malloc tuning when JBP_NO_MALLOC_TUNING=0',
+     app_fixture: 'integration_valid' do
+
+    ENV['JBP_NO_MALLOC_TUNING'] = '0'
+    run("bin/release #{app_dir}") do |status|
+      expect(status).to be_success
+      expect(YAML.load(stdout.string)['default_process_types']['web']).to match(/^MALLOC_ARENA_MAX=2 .*/)
+    end
+  end
+
+  it 'when env contains value, don\'t include it to the command line',
+     app_fixture: 'integration_valid' do
+
+    ENV['MALLOC_ARENA_MAX'] = '4'
+    run("bin/release #{app_dir}") do |status|
+      expect(status).to be_success
+      expect(YAML.load(stdout.string)['default_process_types']['web']).not_to match(/^MALLOC_ARENA_MAX.*/)
+    end
+  end
 end
diff --git a/spec/integration_helper.rb b/spec/integration_helper.rb
index e768cf46b5..90e5bdf372 100644
--- a/spec/integration_helper.rb
+++ b/spec/integration_helper.rb
@@ -40,6 +40,7 @@
 
   after do
     FileUtils.rm_rf buildpack_dir
+    ENV.delete('JBP_NO_MALLOC_TUNING')
   end
 
   def run(command)