A gotcha with javascript objects

Matija

November 23, 2015

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Spent some time today figuring this one. I got too used to perl auto-vivifying objects (or hashes – same thing in Perl5). It seems javascript does the opposite: if a member of of a structure is a string, and then you assign to it as if to an object, it will simply IGNORE your assignment. […]

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Why is my munin slow and how to speed it up

At $work we are monitoring a network of hundreds of servers, and that means that we end up recording hundreds of thousands of variable values every five minutes. After a while, the server started slowing down, taking more than 300 seconds to collect the data. Since it has a whole-system lock, that means the next […]

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A munin plugin to monitor each CPU core separately

Monitoring each core separately may seem like a waste – after all, we have an overall CPU usage already available under “system” in munin, isn’t that enough? It turns out that it isn’t. Sometimes, when using top on a multicore/multicpu machine, you can see a process pegged at 100%, while other processes are comfortably using […]

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Keeping a bunch of processes running

From time to time, I need some processes that keep running. It they were simple daemons, I could use something like monit, but what if I need X instances of worker A and Y instances of worker B? I whipped up a quick script that makes it pretty easy to do that, when needed: #!/usr/bin/perl […]

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Munin-async 2.0.17 on Ubuntu 12.04

Matija

October 26, 2013

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Munin authors have moved on in their development and if you are going to be installing munin-async on any system, I strongly recommend that you use the latest version (2.0.17 at the time of writing), which fixes a number of problems I described in a previous article on Installing munin-async. The only problem I had […]

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Making an IPv6 addressing plan

By now, hopefully, you not only realize that you need IPv6, but that you need to replace any ISP that is not able to give you IPv6 connectivity with one who can. But now, you have a different problem. Your ISP probably gave you more addresses than exist on the whole IPv4 internet, just for […]

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Using rrdcached with munin on Ubuntu

When you have munin following many hosts with many variables tracked on each, you will inevitably find your munin server is overwhelmed with IO (rising iowait values, the server sometimes having excursions where it just gets overwhelmed with IO). The 1.4.7-1 version of rrdcached did NOT install cleanly on my Ubuntu 12.04 server: the package […]

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Massive data loss in MySQL 5.5 with master-master replication.

If you put two mysql servers into a master<->master replication and then change the port of one of the servers, data magically disappears from the first master server. I’ve been able to repeat that (twice) bith with a mixed (mysql 5.1<-> mysql 5.5) setup and with a pure Ubuntu 12.04, mysql 5.5 <-> mysql 5.5 […]

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Installing munin-async

With the latest versions of munin-async, this article is out of date. Instructions for munin 2.0.17 on Ubuntu 12.04 are here When using munin, one often runs into one of two problems: ┬áthere are so many nodes to update, the update takes more than the update interval some servers may be connected over flaky lines, […]

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Protected: IPv6 transition for beginners

Matija

April 21, 2012

ideas

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