random tech stuffs
One of the arguments I frequently hear against threads is that the synchronization problems are a pain in the ass to deal with. They are hard to reproduce, hard to debug, blah blah, etc etc. Well it turns out, I am kinda tired of dealing with broken threads in Ruby and also threadsaftey issues in gems which I don’t have control over. So I’ve been playing around with...
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Threading in Ruby as been busted for a long time. Back in 1.8.7, I actually got segfaults in threaded code. Thankfully, those went away in 1.9, but now I’ve come across a new problem which is almost as bad, save for that I can actually do something about it. The problem happens when a thread locks a Mutex (or Monitor) inside a timeout block and the timeout expires before the thread can...
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Either Rails.cache or memcache-client (or the combination of the two) is not thread safe. I was seeing symptoms like the wrong data being fetched for a given key (getting hash when expecting an array and vice versa). What’s worse is that some data even got written to the wrong keys. At first I was going to make a SynchronizedMemCacheStore in the same spirit as SynchronizedMemoryStore in...
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This is a guide on how to mimic an OS X file server using Linux and the open source implementation of AFP, Netatalk. These instructions are for Ubuntu Server 10.04, but should translate pretty easily to other distros. I have a Linux NAS, but all my other computers are Macs. NFS is simple, but buggy. There are all sorts of problems if you disconnect from the network without unmounting first. ...
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We switched back to Monit after experimenting some with God (oh, what a nightmare). This post is just meant to be a collection of tips for working with Monit. I’ll update it as I discover/remember more. 1. Monit does not honor limits.conf We have a Solr process with 3 cores. The number of open file descriptors can get pretty big between optimizes, exceeding the default limit of 1024 in...
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