title: nodejs v8 memory gc allocation failure
body: <p>I am trying to profile nodejs v8 memory with a do nothing server.
    I used node-memwatch to get heap diff. I collect heap info before connecting and after connection tore down. I used node-memwatch. I tried 200 concurrent connections from client side.</p>
  
  <p>Here is the gc trace after connection tore down.</p>
  
  <p>can anyone help me to understand:</p>
  
  <p>1.why are memory increasing ? after connections tore down, the server is absolutely doing nothing. shouldn't it suppose to always drop as garbages being collected ?<br>
  2. what is are those allocation failure ? How do I really interpret the trace here ?</p>
  
  <pre><code> 15802 ms: Mark-sweep 8.9 (45.0) -&gt; 8.1 (45.0) MB, 58 ms [allocation failure] [GC in old space forced by flags].
   16144 ms: Mark-sweep 9.2 (45.0) -&gt; 8.4 (45.0) MB, 53 ms [allocation failure] [GC in old space forced by flags].
   16495 ms: Mark-sweep 9.5 (45.0) -&gt; 8.7 (46.0) MB, 60 ms [allocation failure] [GC in old space forced by flags].
   16837 ms: Mark-sweep 9.8 (46.0) -&gt; 9.0 (46.0) MB, 56 ms [allocation failure] [GC in old space forced by flags].
   17197 ms: Mark-sweep 10.1 (46.0) -&gt; 9.4 (46.0) MB, 62 ms [allocation failure] [GC in old space forced by flags].
   17905 ms: Mark-sweep 11.5 (46.0) -&gt; 10.0 (47.0) MB, 74 ms [Runtime::PerformGC] [GC in old space forced by flags].                                                               
   18596 ms: Mark-sweep 12.2 (47.0) -&gt; 10.7 (47.0) MB, 75 ms [Runtime::PerformGC] [GC in old space forced by flags].
   19315 ms: Mark-sweep 12.8 (47.0) -&gt; 11.3 (48.0) MB, 83 ms [allocation failure] [GC in old space forced by flags].
   20035 ms: Mark-sweep 13.4 (48.0) -&gt; 12.0 (49.0) MB, 90 ms [Runtime::PerformGC] [GC in old space forced by flags].
   21487 ms: Mark-sweep 16.0 (49.0) -&gt; 13.2 (50.0) MB, 96 ms [Runtime::PerformGC] [GC in old space forced by flags].
   22950 ms: Mark-sweep 17.3 (50.0) -&gt; 14.5 (52.0) MB, 116 ms [Runtime::PerformGC] [GC in old space forced by flags].
   24376 ms: Mark-sweep 18.8 (52.0) -&gt; 15.9 (53.0) MB, 114 ms [allocation failure] [GC in old space forced by flags].
   25849 ms: Mark-sweep 19.9 (53.0) -&gt; 17.2 (54.0) MB, 129 ms [Runtime::PerformGC] [GC in old space forced by flags].
   28773 ms: Mark-sweep 25.2 (54.0) -&gt; 19.7 (57.0) MB, 149 ms [allocation failure] [GC in old space forced by flags].
   31725 ms: Mark-sweep 27.7 (57.0) -&gt; 22.2 (59.0) MB, 172 ms [Runtime::PerformGC] [GC in old space forced by flags].
   34678 ms: Mark-sweep 30.2 (59.0) -&gt; 24.7 (61.0) MB, 190 ms [Runtime::PerformGC] [GC in old space forced by flags].
   44045 ms: Mark-sweep 28.4 (61.0) -&gt; 25.8 (63.0) MB, 180 ms [idle notification] [GC in old space forced by flags].
   44216 ms: Mark-sweep 25.8 (63.0) -&gt; 25.8 (63.0) MB, 170 ms [idle notification] [GC in old space requested].
   57471 ms: Mark-sweep 26.9 (63.0) -&gt; 25.8 (62.0) MB, 167 ms [Runtime::PerformGC] [GC in old space forced by flags].
   57651 ms: Mark-sweep 26.8 (62.0) -&gt; 25.5 (62.0) MB, 160 ms [Runtime::PerformGC] [GC in old space forced by flags].
   57828 ms: Mark-sweep 26.5 (62.0) -&gt; 25.5 (62.0) MB, 159 ms [Runtime::PerformGC] [GC in old space forced by flags].
  </code></pre>
  
  <p>Thanks,</p>