July 2002
Intermediate to advanced
528 pages
15h 13m
English
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Heartbeat Server
The Heartbeat server (HBS) is used by the system to keep track of which servers are up and which are down. Heartbeating refers to a server transmitting regular pulses to a multicast address as a signal to the other servers that it is up.
Transmit Thread
The Transmit thread is the multicast group. Any type of server that uses an HBS sends heartbeat pulses to the multicast group. If a server wants to determine the status of other servers on the network, it polls the Multicast thread regularly. The polling frequency is configurable and set to a default value of 250 milliseconds.
Receiving Heartbeats
The RX thread specifies which servers a particular server listens to for heartbeats. Some servers receive the TX thread without keeping track of which servers are up; other servers listen for heartbeats from specific servers.
Each server has a data container that it uses to match incoming heartbeats. The matching criteria include server type, IP address, and port. Every server receives every multicast heartbeat but throws away those that do not match the list in its data container. If heartbeats are not received for servers listed in the data container, it is assumed that those servers are down.
Housekeeping
Every 250 milliseconds, a heartbeat is received and marked. Housekeeping checks if any anticipated heartbeats fail to appear. The Housekeeping thread flags the counter for missed heartbeats and increments the counter by 1. If the counter matches the maximum missed heartbeat ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.