* Call malloc_trim(0) after System.gc() on Linux to make sure me…

…mory gets released (issue bytedeco/javacpp-presets#423)
bytedeco · Jul 9, 2017 · 86e4d57 · 86e4d57
1 parent c4fa2c1
commit 86e4d57
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Showing 3 changed files with 17 additions and 3 deletions.
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -1,4 +1,5 @@
 
+ * Call `malloc_trim(0)` after `System.gc()` on Linux to make sure memory gets released ([issue bytedeco/javacpp-presets#423](https://github.com/bytedeco/javacpp-presets/issues/423))
  * Make public the `Pointer.formatBytes()` and `Pointer.parseBytes()` static methods
  * Use `Integer.decode()` instead of `parseInt()` on integer literals to support hexadecimal and octal numbers
  * Add `Builder.encoding` option to let users specify I/O character set name ([issue bytedeco/javacpp-presets#195](https://github.com/bytedeco/javacpp-presets/issues/195))

diff --git a/src/main/java/org/bytedeco/javacpp/Pointer.java b/src/main/java/org/bytedeco/javacpp/Pointer.java
@@ -325,7 +325,7 @@ static class DeallocatorThread extends Thread {
 
     /** Maximum number of times to call {@link System#gc()} before giving up with {@link OutOfMemoryError}.
      * Set via "org.bytedeco.javacpp.maxretries" system property, defaults to 10, where each retry is followed
-     * by a call to {@code Thread.sleep(100)}. */
+     * by a call to {@code Thread.sleep(100)} and {@code Pointer.trimMemory()}. */
     static final int maxRetries;
 
     public static String formatBytes(long bytes) {
@@ -430,6 +430,9 @@ public static long maxPhysicalBytes() {
         return maxPhysicalBytes;
     }
 
+    /** Makes sure to return freed memory to the system, as required by Linux, at least. */
+    @Name("JavaCPP_trimMemory") private static native boolean trimMemory();
+
     /** Returns the amount of physical memory currently used by the whole process, or 0 if unknown.
      * Also known as "resident set size" (Linux, Mac OS X, etc) or "working set size" (Windows). */
     @Name("JavaCPP_physicalBytes") public static synchronized native long physicalBytes();
@@ -547,17 +550,18 @@ protected <P extends Pointer> P deallocator(Deallocator deallocator) {
                     while (count++ < maxRetries && ((maxBytes > 0 && DeallocatorReference.totalBytes + r.bytes > maxBytes)
                                          || (maxPhysicalBytes > 0 && (lastPhysicalBytes = physicalBytes()) > maxPhysicalBytes))) {
                         if (logger.isDebugEnabled()) {
-                            logger.debug("Calling System.gc() in " + this);
+                            logger.debug("Calling System.gc() and Pointer.trimMemory() in " + this);
                         }
                         // try to get some more memory back
                         System.gc();
                         Thread.sleep(100);
+                        trimMemory();
                     }
                 } catch (InterruptedException ex) {
                     // reset interrupt to be nice
                     Thread.currentThread().interrupt();
                 } catch (UnsatisfiedLinkError e) {
-                    // old binaries with physicalBytes() missing -> ignore for backward compatibility
+                    // old binaries with physicalBytes() or trimMemory() missing -> ignore for backward compatibility
                     if (logger.isDebugEnabled()) {
                         logger.debug(e.getMessage());
                     }

diff --git a/src/main/java/org/bytedeco/javacpp/tools/Generator.java b/src/main/java/org/bytedeco/javacpp/tools/Generator.java
@@ -278,6 +278,7 @@ boolean classes(boolean handleExceptions, boolean defineAdapters, boolean conver
         out.println("#endif");
         out.println();
         out.println("#ifdef __linux__");
+        out.println("    #include <malloc.h>");
         out.println("    #include <sys/types.h>");
         out.println("    #include <sys/stat.h>");
         out.println("    #include <sys/sysinfo.h>");
@@ -430,6 +431,14 @@ boolean classes(boolean handleExceptions, boolean defineAdapters, boolean conver
         out.println("    va_end(ap);");
         out.println("}");
         out.println();
+        out.println("static inline jboolean JavaCPP_trimMemory() {");
+        out.println("#if defined(__linux__) && !defined(__ANDROID__)");
+        out.println("    return (jboolean)malloc_trim(0);");
+        out.println("#else");
+        out.println("    return 0;");
+        out.println("#endif");
+        out.println("}");
+        out.println();
         out.println("static inline jlong JavaCPP_physicalBytes() {");
         out.println("    jlong size = 0;");
         out.println("#ifdef __linux__");