slfritchie

Riak Source Code Reading #27: Riak KV backend API and storage

The Riak KV backend store API

behaviour_info(callbacks) ->
    [
     {api_version,0},

slfritchie

Erlang Tracing: more than you wanted to know

Rough Outline

• What can be traced?
• How can trace events be specified?
• "match specifications": twisty passages, all alike
• WTF, can I just use DTrace and drink my coffee/beer/whisky in peace?
• Trace delivery mechanisms: pick one of two

slfritchie

Purpose: To prevent scheduler collapse by disabling scheduler sleep periods.
This patch is relative to R16B01 pre-release but may be applied (with "fuzz")
on R15B01 and R15B03-1 without difficulty.

The new flag, "+zdss", must be used with "+scl false" flag to be successful.
See the erl.xml document for a description.  Example use:

  erl +scl false +zdss 500:500

Note that this flag used to be called "+zdnfgtse"

slfritchie

Grimsby
(n.) --- A lump of something gristly and foul-tasting concealed in a
mouthful of stew or pie.  Grimsbies are sometimes merely the result of
careless cookery, but more often they are placed there deliberately by
Freemasons.  Grimsbies can be purchased in bulk from any respectable
Masonic butcher on giving him the secret Masonic handbag.  One is then
placed in a guest's food to see if he knows the correct Masonic method of
dealing with it.  If the guest is not a Mason, the host may find it
entertaining to watch how he handles the obnoxious object.  It may be:
a). manfully swollowed, invariably bringing tears to the eyes, b). chewed

slfritchie

Threads (all the same conversation, really) on the erlang-questions mailing list about R15B scheduler woes: schedulers appear to go to sleep/offline if NIFs do not return control back to the VM's scheduler code quickly enough, e.g., executing for longer than 1 millisecond.

• http://erlang.org/pipermail/erlang-questions/2012-October/069507.html
• http://erlang.org/pipermail/erlang-questions/2012-October/069589.html
• http://erlang.org/pipermail/erlang-questions/2012-November/070411.html

slfritchie

ref2_test() ->
    Ref = make_ref(),
    ref_fixed(Ref),
    receive Ref -> Ref after 500 -> bummer end.