Disable explicit GC by default

We don't rely upon GC to cleanup mappedbytebuffers, we unmap them
explicitly on close in lucene. But the JDK has crazy loops with
explicit GCs in exceptional cases to try to force unmapping.

In general we don't want any of our code or library code calling
this method: so its banned in forbidden-apis as well.

bin/elasticsearch.bat

@@ -62,6 +62,9 @@ REM The path to the heap dump location, note directory must exists and have enou
 REM space for a full heap dump.
 REM JAVA_OPTS=%JAVA_OPTS% -XX:HeapDumpPath=$ES_HOME/logs/heapdump.hprof
 
+REM Disables explicit GC
+set JAVA_OPTS=%JAVA_OPTS% -XX:+DisableExplicitGC
+
 set ES_CLASSPATH=%ES_CLASSPATH%;%ES_HOME%/lib/${project.build.finalName}.jar;%ES_HOME%/lib/*;%ES_HOME%/lib/sigar/*
 set ES_PARAMS=-Delasticsearch -Des-foreground=yes -Des.path.home="%ES_HOME%"
 

bin/elasticsearch.in.sh

@@ -62,3 +62,6 @@ JAVA_OPTS="$JAVA_OPTS -XX:+HeapDumpOnOutOfMemoryError"
 # The path to the heap dump location, note directory must exists and have enough
 # space for a full heap dump.
 #JAVA_OPTS="$JAVA_OPTS -XX:HeapDumpPath=$ES_HOME/logs/heapdump.hprof"
+
+# Disables explicit GC
+JAVA_OPTS="$JAVA_OPTS -XX:+DisableExplicitGC"

bin/service.bat

@@ -160,6 +160,9 @@ REM The path to the heap dump location, note directory must exists and have enou
 REM space for a full heap dump.
 REM JAVA_OPTS=%JAVA_OPTS% -XX:HeapDumpPath=$ES_HOME/logs/heapdump.hprof
 
+REM Disables explicit GC
+set JAVA_OPTS=%JAVA_OPTS% -XX:+DisableExplicitGC
+
 if "%DATA_DIR%" == "" set DATA_DIR=%ES_HOME%\data
 
 if "%WORK_DIR%" == "" set WORK_DIR=%ES_HOME%

core-signatures.txt

@@ -51,5 +51,8 @@ java.lang.Object#notifyAll()
 java.lang.Math#abs(int)
 java.lang.Math#abs(long)
 
+@defaultMessage Please do not try to stop the world
+java.lang.System#gc()
+
 @defaultMessage Use Long.compare instead we are on Java7
 com.google.common.primitives.Longs#compare(long,long)