djangosampler

Samples a percentage of SQL queries and groups them together for easy viewing
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  • Rating:
  • License:
  • The Apache License 2.0
  • Price:
  • FREE
  • Publisher Name:
  • Colin Howe
  • Publisher web site:
  • https://github.com/colinhowe/

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djangosampler Description

djangosampler is a Django app that allows you to sample a percentage of your queries (SQL, Mongo, etc) and view the ones that are taking up the most time. The queries are grouped together by where they originated from in your code.InstallationInstall:python setup.py installConfigure:- Add djangosampler to your INSTALLED_APPS- Add the tables (manage.py syncdb or manage.py migrate if you use South)- Add the views: urlpatterns += patterns('', (r'^sampler/', include('djangosampler.urls')), )- Set DJANGO_SAMPLER_FREQ to a value other than 0- Set DJANGO_SAMPLER_PLUGINS to a list of plugins. For just sampling SQL a sensible default is: DJANGO_SAMPLER_PLUGINS = ( 'djangosampler.plugins.sql.Sql', # Plugins are applied in the same order as this list )- There are several plugins available and it is worthwhile reading through them to get the most use out of this tool.- If you are using cost based sampling then set DJANGO_SAMPLER_BASE_TIME to the expected duration of a normal query in seconds. By default this is set to 5ms.Viewing ResultsAfter letting the sampler run for a while you will be able to view queries (grouped by their origin) at the URL you configured.ConfigurationDJANGO_SAMPLER_PLUGINSDjango Sampler has a plugin architecture to allow you to control how much data you want to be collected.In your settings.py add the following:DJANGO_SAMPLER_PLUGINS = ( 'djangosampler.plugins.sql.Sql', # Plugins are applied in the same order as this list)The example above will add the SQL plugin.Available plugins and their settings are described in the Plugins section below.DJANGO_SAMPLER_FREQDJANGO_SAMPLER_FREQ configures the percentage of queries that will be recorded. It should be between 0.0 and 1.0.If this is not set then no plugins will be installed and your code will run as normal.DJANGO_SAMPLER_USE_COSTDJANGO_SAMPLER_USE_COST will enable cost-based sampling. This causes queries that run for a long time to be sampled more often than short queries.The chance that a query is sampled is multiplied by the total time the query takes. If a query takes 2 seconds then it will be twice as likely to be sampled as a query that takes 1 second.The cost for a query is adjusted to account for this as follows:cost = max(1.0, time * DJANGO_SAMPLER_FREQ) / DJANGO_SAMPLER_FREQPluginsA list of available plugins follows. You can write your own plugin and this is described in the section 'Writing Your Own Plugins'.Django SQLPlugin class: djangosampler.plugins.sql.SqlThe SQL sampler plugin will sample a percentage of SQL queries that occur in your application. The samples will be grouped by query and stack traces will be recorded to find where the queries are originating.Django RequestsPlugin class: djangosampler.plugins.request.RequestThe request plugin installs a Middleware that will sample the time taken by requests.Sample any codeThis is not strictly a plugin. This is a context manager that will allow you to mark blocks of code and sample how long the blocks take to run. E.g.:from djangosampler.sampler import samplingwith sampling('my_code', 'some_fn'): do_something_slow()CeleryPlugin class: djangosampler.plugins.celery_task.CeleryThe Celery plugin uses Celery's signals to sample the time taken to execute tasks.MongoDBPlugin class: djangosampler.plugins.mongo.MongoThe MongoDB plugin will sample a percentage of Mongo commands (queries, inserts, etc) that occur in your application. The samples will be grouped by command and stack traces will be recorded to find where the queries are originating.Product's homepage


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