erlang/otp — pull request #161 by paulgray (2013-12-10 00:04:39+00:00)
Title: Add system_monitor of long_message_queue

New system_monitor flag allows the VM to inform monitoring process about
processes whose message queues get too long. In order to avoid overloads
of the monitoring process only one monitor message is sent after passing
the configured mailbox size threshold. Another monitor message can be
generated only once the message queue length drops again below the alarm
level.