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PORuby, Mongodb, Anemone: web crawler with possible memory leak?
 

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    <p>I began to learn about web crawlers recently and I built a sample crawler with Ruby, <a href="http://anemone.rubyforge.org/" rel="noreferrer">Anemone</a>, and <a href="http://www.mongodb.org/" rel="noreferrer">Mongodb</a> for storage. I'm testing the crawler on a massive public website with possibly billions of links.</p> <p>The crawler.rb is indexing the correct information, although when I check the memory use in activity monitor it shows the memory constantly growing. I have only run the crawler for about 6-7 hours and the memory is showing 1.38GB for mongod and 1.37GB for the Ruby process. It seems to be growing about 100MB every hour or so. </p> <p>It seems that I might have a memory leak? Is their a more optimal way I can achieve the same crawl without the memory escalating out of control so that it can run longer?</p> <pre class="lang-rb prettyprint-override"><code># Sample web_crawler.rb with Anemone, Mongodb and Ruby. require 'anemone' # do not store the page's body. module Anemone class Page def to_hash {'url' =&gt; @url.to_s, 'links' =&gt; links.map(&amp;:to_s), 'code' =&gt; @code, 'visited' =&gt; @visited, 'depth' =&gt; @depth, 'referer' =&gt; @referer.to_s, 'fetched' =&gt; @fetched} end def self.from_hash(hash) page = self.new(URI(hash['url'])) {'@links' =&gt; hash['links'].map { |link| URI(link) }, '@code' =&gt; hash['code'].to_i, '@visited' =&gt; hash['visited'], '@depth' =&gt; hash['depth'].to_i, '@referer' =&gt; hash['referer'], '@fetched' =&gt; hash['fetched'] }.each do |var, value| page.instance_variable_set(var, value) end page end end end Anemone.crawl("http://www.example.com/", :discard_page_bodies =&gt; true, :threads =&gt; 1, :obey_robots_txt =&gt; true, :user_agent =&gt; "Example - Web Crawler", :large_scale_crawl =&gt; true) do | anemone | anemone.storage = Anemone::Storage.MongoDB #only crawl pages that contain /example in url anemone.focus_crawl do |page| links = page.links.delete_if do |link| (link.to_s =~ /example/).nil? end end # only process pages in the /example directory anemone.on_pages_like(/example/) do | page | regex = /some type of regex/ example = page.doc.css('#example_div').inner_html.gsub(regex,'') rescue next # Save to text file if !example.nil? and example != "" open('example.txt', 'a') { |f| f.puts "#{example}"} end page.discard_doc! end end </code></pre>
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    1. CODid you figure out the cause of the leak? If you think it was bug in Anemone, did you report it over on their [issue tracker](https://github.com/chriskite/anemone/issues)?
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    2. CORelated issues mentioned on the Anemone issue tracker include: [memory leak?](https://github.com/chriskite/anemone/issues/49), [memory leak or inefficient memory handling](https://github.com/chriskite/anemone/issues/29), and [Fixes OutOfMemory error for large sites](https://github.com/chriskite/anemone/pull/30)
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    3. COI reported it around the same time as posting here on SO. I was able to crawl what my task required by adding the suggested fixes and it made my crawl last a lot longer, although tbh the ram usage was steadily growing, just not as fast as it was previously. I'm still not sure what causes the memory leak.
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