title: Performance overhead of UseAdaptiveSizePolicy
body: <p>I'm observing very long stop-the-world pauses when my application is changing ratio between Eden and Survivor Spaces. I'm not using any custom JVM flags, so <code>UseAdaptiveSizePolicy</code> is enabled by default. Host has 32 GB of RAM. I have JDK 8.</p>
  
  <pre><code>Eden Space: used = 833208K, max = 1263616K
  Survivor Space: used = 634357K, max = 634368K
  Old Gen: used = 2456700K, max = 5480448K
  (11s stop-the-world)
  Eden Space: used = 24665K, max = 1105920K
  Survivor Space: used = 297749K, max = 842240K
  Old Gen: used = 3094701K, max = 5480448K
  </code></pre>
  
  <p>In my case it took JVM 11 s to decrease Eden by ~100 MB, increase Survivor by ~200 MB and tenure about ~600 MB of objects. Are these really so costly operations? What could have happened?</p>
  
  <p>Here is log from the GC:</p>
  
  <pre><code>2017-10-19T10:24:28.845+0100: 201.951: [Full GC (Ergonomics) [PSYoungGen: 337425K-&gt;60051K(1966080K)] [ParOldGen: 2877063K-&gt;3135388K(4417536K)] 3214488K-&gt;3195440K(6383616K), [Metaspace: 85871K-&gt;85871K(1126400K)], 11.0121325 secs] [Times: user=45.02 sys=2.24, real=10.01 secs] 
  </code></pre>