Class MemoryAssert


public class MemoryAssert extends Object
Static utility methods for verifying heap memory usage. Uses the INSANE library to traverse the heap from within your test.

Object sizes are in an idealized JVM in which pointers are 4 bytes (realistic even for modern 64-bit JVMs in which -XX:+UseCompressedOops is the default) but objects are aligned on 8-byte boundaries (so dropping an int field does not always save memory).

import static org.jvnet.hudson.test.MemoryAssert.*; to use.

  • Method Details

    • assertHeapUsage

      public static void assertHeapUsage(Object o, int max) throws Exception
      Verifies that an object and its transitive reference graph occupy at most a predetermined amount of memory. The referents of WeakReference and the like are ignored.

      To use, run your test for the first time with max of 0; when it fails, use the reported actual size as your assertion maximum. When improving memory usage, run again with 0 and tighten the test to both demonstrate your improvement quantitatively and prevent regressions.

      o - the object to measure
      max - the maximum desired memory usage (in bytes)
    • increasedMemory

      public static List<MemoryAssert.HistogramElement> increasedMemory(Callable<Void> callable, org.netbeans.insane.scanner.Filter... filters) throws Exception
      Counts how much more memory is held in Jenkins by doing some operation.
      callable - an action
      filters - things to exclude
      a histogram of the heap delta after running the operation
    • assertGC

      @Deprecated public static void assertGC(WeakReference<?> reference)
    • assertGC

      public static void assertGC(WeakReference<?> reference, boolean allowSoft)
      Forces GC by causing an OOM and then verifies the given WeakReference has been garbage collected.
      reference - object used to verify garbage collection.
      allowSoft - if true, pass even if SoftReferences apparently needed to be cleared by forcing an OutOfMemoryError; if false, fail in such a case (though the failure will be slow)