$ node --expose-gc --trace-gc --log-gc
[40433] 1397730668633 ms: Mark-sweep 0.5 (34.0) -> 0.5 (34.0) MB, 0 ms [Logger::LogCodeObjects] [GC in old space requested].
[40433] 1397730668633 ms: Mark-sweep 0.5 (34.0) -> 0.4 (34.0) MB, 0 ms [Logger::LogCompiledFunctions] [GC in old space requested].
> var a = [];
[40433]     5200 ms: Scavenge 2.6 (37.0) -> 2.4 (37.0) MB, 1 ms [Runtime::PerformGC].
undefined
> for (var i = 0; i < 10000; i++) a.push('' + i);
[40433]    42607 ms: Scavenge 3.6 (38.0) -> 3.2 (39.0) MB, 0 ms [Runtime::PerformGC].
10000
> a.length
10000
> a = null;
null
> global.gc();
[40433]    68105 ms: Mark-sweep 3.6 (39.0) -> 2.8 (39.0) MB, 4 ms [gc extension] [GC in old space requested].
undefined
> 
(^C again to quit)
>