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This document attempts to give some hints for people that are wanting to work
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You can run the loggerhead test suite as a bzr plugin. To run just the
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bzr selftest -s bp.loggerhead
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As a web service, Loggerhead will often be hit by multiple requests. We want
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to make sure that loggerhead can scale with many requests, without performing
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poorly or crashing under the load.
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There is a command ``bzr load-test-loggerhead`` that can be run to stress
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loggerhead. A script is given, describing what requests to make, against what
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URLs, and for what level of parallel activity.
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Load Testing Multiple Instances
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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One way that Launchpad provides both high availability and performance scaling
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is by running multiple instances of loggerhead, serving the same content. A
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proxy is then used to load balance the requests. This also allows us to shut
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down one instance for upgrading, without interupting service (requests are
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just routed to the other instance).
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However, multiple processes poses an even greater risk that caches will
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conflict. As such, it is useful to test that changes don't introduce coherency
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issues at load. ``bzr load-test-loggerhead`` can be configured with a script
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that will make requests against multiple loggerhead instances concurrently.
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To run multiple instances, it is often sufficient to just spawn multiple
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servers on different ports. For example::
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$ bzr serve --http --port=8080 &
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$ bzr serve --http --port=8081 &
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There is a simple example script already in the source tree::
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$ bzr load-test-loggerhead load_test_scripts/multiple_instances.script
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HACKING
