Removing latency spikes. Garbage collector related?

Gregory Collins greg at
Mon Sep 28 18:02:35 UTC 2015

On Mon, Sep 28, 2015 at 9:08 AM, Will Sewell <me at> wrote:

> If it is the GC, then is there anything that can be done about it?

   - Increase value of -A (the default is too small) -- best value for this
   is L3 cache size of the chip
   - Increase value of -H (total heap size) -- this will use more ram but
   you'll run GC less often
   - This will sound flip, but: generate less garbage. Frequency of GC runs
   is proportional to the amount of garbage being produced, so if you can
   lower mutator allocation rate then you will also increase net productivity.
   Built-up thunks can transparently hide a lot of allocation so fire up the
   profiler and tighten those up (there's an 80-20 rule here). Reuse output
   buffers if you aren't already, etc.


Gregory Collins <greg at>
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