012fd41fc0
Unlike cache, dirty memory cannot be evicted at will, so we must limit it. This patch establishes a hard limit of 50% of all memory. Above that, new requests are not allowed to start. This allows the system some time to clean up memory. Note that we will need more fine-grained bandwidth control than this; the hard limit is the last line of defense against running our of reclaimable memory. Tested with a mixed read/write load; after reads start to dominate writes (due to the proliferation of small sstables, and the inability of compaction to keep up, dirty memory usage starts to climb until the hard stop prevents it from climbing further and ooming the server).
#Urchin
##Building Urchin
In addition to required packages by Seastar, the following packages are required by Urchin.
Submodules
Urchin uses submodules, so make sure you pull the submodules first by doing:
git submodule init
git submodule update --recursive
Building urchin on Fedora
Installing required packages:
sudo yum install yaml-cpp-devel lz4-devel zlib-devel snappy-devel jsoncpp-devel thrift-devel antlr3-tool antlr3-C++-devel libasan libubsan
Building urchin on Ubuntu 14.04
Installing required packages:
sudo apt-get install libyaml-cpp-dev liblz4-dev zlib1g-dev libsnappy-dev libjsoncpp-dev