[erlang-questions] Backpressure

Ulf Wiger ulf.wiger@REDACTED
Thu Jul 28 22:10:59 CEST 2011

On 28 Jul 2011, at 20:16, Jay Nelson wrote:

>> Ulf Wiger wrote:
>> The problems with Distributed Erlang are related to a heavy-handed backpressure solution, where processes trying to send to the dist_port are simply suspended if the output queue exceeds a given threshold.
> Does this only apply to distributed erlang? What about punishment of processes communicating within a node? I've seen senders using more time in local comms*.

Only Distributed Erlang. Local message passing does come with a form of backpressure too, as senders are punished with extra reductions if the receiver's message queue is big. I think this feature should go away, as it makes the message send more complex from a scalability point of view, but I know others like it… One can probably reduce locking by allowing the queue length value to be somewhat old, for example.

Ulf W

Ulf Wiger, CTO, Erlang Solutions, Ltd.

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