Erlang 2017/01/06

Ping-Pong

Ping-Pong

ping_pong.ex

Context Switch1.x us on my machine(2.5 GHz Intel Core i7).

https://gist.github.com/killme2008/1f8a58ebd198ffbb04d4af25f9eb9135

Process Structure C Struct : erl_process.h

PCB: process control block

process id

stack/heap position

argument registers

program counter

stack

private heap : compound data structures, such as tuples, lists etc.

heap fragments: used when there is not enough free space in the heap and garbage collection cannot be performed to get more free memory.

https://github.com/erlang/otp/blob/9cb4770469218f65dbaec6c71d12b4aa722ac791/erts/emulator/beam/erl_process.h#L935

Erlang Process

Stack and Heap

Process

http://www.cnblogs.com/me-sa/archive/2011/11/13/erlang0014.html

http://www.cnblogs.com/me-sa/archive/2011/11/13/erlang0014.htmlhttp://www.cnblogs.com/me-sa/archive/2011/11/13/erlang0014.html

Message Passing send / receive

Coping message

Sends a message to it self, doesnt copy.

binary

< 64 : private heap

>= 64 :

Scheduler Reductions: 2000

erl_vm.h :

#define CONTEXT_REDS 2000 /* Swap process out after this number */

erts_schedule in erl_process.c

consumes all its reductions

or pauses to wait for a message

Four priorities: low | normal | high | max

Four queues: ports, maximum, high, normal/low.

ports > max > high > normal/low

normal/low: skip a low priority process for a number of times

Round-Robin in queue.

https://github.com/erlang/otp/blob/86d1fb0865193cce4e308baa6472885a81033f10/erts/emulator/beam/erl_vm.h#L39https://github.com/erlang/otp/blob/9cb4770469218f65dbaec6c71d12b4aa722ac791/erts/emulator/beam/erl_process.c#L9484

A Scheduler

Google images

SMP

Multiple processors => Multiple scheduler

erl +S Schedulers:SchedulerOnline

defaults to logical processors configured

Balancing workload on multiple processors

SMP Schedulers

http://ithelp.ithome.com.tw/articles/10161709

Workload Balancing Check workload periodically by one scheduler

Default period: 2000*2000 reductions.

erl_process.c:

#define ERTS_RUNQ_CHECK_BALANCE_REDS_PER_SCHED (2000*CONTEXT_REDS)

check_balance in erl_process.c

During a period:

work sharing/stealing

determines the number of active schedulers for the next period based on the load of the current period

https://github.com/erlang/otp/blob/9cb4770469218f65dbaec6c71d12b4aa722ac791/erts/emulator/beam/erl_process.c#L56https://github.com/erlang/otp/blob/9cb4770469218f65dbaec6c71d12b4aa722ac791/erts/emulator/beam/erl_process.c#L4621

Number of schedulers

Next active schedulers

Work migration

Memory Management

http://erlang.org/doc/man/erts_alloc.html

http://erlang.org/doc/man/erts_alloc.html

Garbage Collection

Process heap: copying generational garbage collector.

Binary:

https://www.erlang-solutions.com/blog/erlang-19-0-garbage-collector.html

https://www.erlang-solutions.com/blog/erlang-19-0-garbage-collector.htmlhttps://www.erlang-solutions.com/blog/erlang-19-0-garbage-collector.html

GC

Control GC erl +h min_heap_size

spawn min_heap_size/min_bin_vheap_size

:erlang.garbage_collect()

Statistics:

:erlang.process_info(pid, :garbage_collection)

:erlang.system_info(:garbage_collection)

http://www.diva-portal.org/smash/get/diva2:392243/FULLTEXT01.pdf

https://www.erlang-solutions.com/blog/erlang-19-0-garbage-collector.html

https://hamidreza-s.github.io/erlang/scheduling/real-time/preemptive/migration/2016/02/09/erlang-scheduler-details.html

http://www.cnblogs.com/me-sa/archive/2011/11/13/erlang0014.html

https://www.zhihu.com/question/24732869

https://www.erlang-solutions.com/blog/erlang-19-0-garbage-collector.htmlhttps://www.erlang-solutions.com/blog/erlang-19-0-garbage-collector.htmlhttps://hamidreza-s.github.io/erlang/scheduling/real-time/preemptive/migration/2016/02/09/erlang-scheduler-details.htmlhttps://hamidreza-s.github.io/erlang/scheduling/real-time/preemptive/migration/2016/02/09/erlang-scheduler-details.htmlhttps://www.zhihu.com/question/24732869