Commits on Feb 5, 2013

1. zlib: reduce memory consumption, release early …

   In zlibBuffer(), don't wait for the garbage collector to reclaim the zlib memory
   but release it manually. Reduces memory consumption by a factor of 10 or more
   with some workloads.
   
   Test case:
   
     function f() {
       require('zlib').deflate('xxx', g);
     }
     function g() {
       setTimeout(f, 5);
     }
     f();
   
   Observe RSS memory usage with and without this commit. After 10,000 iterations,
   RSS stabilizes at ~35 MB with this commit. Without, RSS is over 300 MB and keeps
   growing.
   
   Cause: whenever the JS object heap hits the high-water mark, the V8 GC sweeps
   it clean, then tries to grow it in order to avoid more sweeps in the near
   future. Rule of thumb: the bigger the JS heap, the lazier the GC can be.
   
   A side effect of a bigger heap is that objects now live longer. This is harmless
   in general but it affects zlib context objects because those are tied to large
   buffers that live outside the JS heap, on the order of 16K per context object.
   
   Ergo, don't wait for the GC to reclaim the memory - it may take a long time.
   
   Fixes #4172.

   

   bnoordhuis committed Feb 5, 2013
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2. zlib: pass object size hint to V8 …

   Inform V8 that the zlib context object is tied to a large off-heap buffer.
   
   This makes the GC run more often (in theory) and improves the accuracy of
   --trace_external_memory.

   

   bnoordhuis committed Feb 5, 2013
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   6b99fd2 View commit details

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