[erlang-questions] what does suspend do ?
Dmitry Kolesnikov
dmkolesnikov@REDACTED
Mon Feb 3 09:45:26 CET 2014
Hello,
This is suspension for garbage collection.
- Dmitry
On 02 Feb 2014, at 23:38, Philip Clarke <send2philip@REDACTED> wrote:
> Hi,
>
> I have been doing some profiling using fprof on my system.
> Using fprof I see that ets:select is calling suspend.
>
> I suspect that I have found a bottleneck where I have an ets table with write_concurrency defined and there are lots of processes doing reads thousands of times per second. But my question is more general to profiling.
>
> What exactly does suspend do ? I suspect it may be an indication that my process has run out of reductions and is preempted by the scheduler ?
> Could anyone confirm please ?
>
> Just in case it is useful, here is the relevant part of my fprof analysis file.
>
> {[{{mymodule,get_values,1}, 6, 2992.735, 31.313}],
> { {ets,select,2}, 6, 2992.735, 31.313}, %
> [{suspend, 92, 1707.908, 0.000},
> {{lists,sum,1}, 6, 1251.655, 0.709},
> {garbage_collect, 7, 1.859, 1.859}]}.
>
> {[{{ets,select,2}, 6, 1251.655, 0.709}],
> { {lists,sum,1}, 6, 1251.655, 0.709}, %
> [{{lists,sum,2}, 6, 1250.946, 0.047}]}.
>
> {[{{lists,sum,1}, 6, 1250.946, 0.047},
> {{lists,sum,2}, 20647, 0.000, 1241.206}],
> { {lists,sum,2}, 20653, 1250.946, 1241.253}, %
> [{suspend, 10, 9.693, 0.000},
> {{lists,sum,2}, 20647, 0.000, 1241.206}]}.
>
> Thanks
> Philip
>
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