title: 100% full Eden space, 0% used Survivor space - Garbage collection not done
body: <p>I have encountered a rather confusing GC case: While the Eden space is 100% full, 0% survivor space is used. When the Eden is full, garbage collection should be triggered, right? </p>
  
  <p>Can there be a case in which the GC daemon is prevented from running? Like a 100% CPU?</p>
  
  <p>We are using <code>jdk-1.7</code>.</p>
  
  <p>What can be the cause? Below is the jmap output. </p>
  
  <p>We also tried to capture a more detailed memory usage using <code>jmap -histo -F</code>, but then the CPU usage dropped to 0% and the java process became unreachable. </p>
  
  <pre><code>using thread-local object allocation.
  Parallel GC with 18 thread(s)
  
  Heap Configuration:
     MinHeapFreeRatio = 40
     MaxHeapFreeRatio = 70
     MaxHeapSize      = 12884901888 (12288.0MB)
     NewSize          = 1310720 (1.25MB)
     MaxNewSize       = 17592186044415 MB
     OldSize          = 5439488 (5.1875MB)
     NewRatio         = 2
     SurvivorRatio    = 8
     PermSize         = 21757952 (20.75MB)
     MaxPermSize      = 85983232 (82.0MB)
     G1HeapRegionSize = 0 (0.0MB)
  
  Heap Usage:
  PS Young Generation
  Eden Space:
     capacity = 4265738240 (4068.125MB)
     used     = 4265738240 (4068.125MB)
     free     = 0 (0.0MB)
     100.0% used
  From Space:
     capacity = 14352384 (13.6875MB)
     used     = 0 (0.0MB)
     free     = 14352384 (13.6875MB)
     0.0% used
  To Space:
     capacity = 14680064 (14.0MB)
     used     = 0 (0.0MB)
     free     = 14680064 (14.0MB)
     0.0% used
  PS Old Generation
     capacity = 8589934592 (8192.0MB)
     used     = 8589931920 (8191.997451782227MB)
     free     = 2672 (0.0025482177734375MB)
     99.99996889382601% used
  PS Perm Generation
     capacity = 41353216 (39.4375MB)
     used     = 41079056 (39.17604064941406MB)
     free     = 274160 (0.2614593505859375MB)
     99.33702858805468% used
  </code></pre>