# A copy of XX has been removed from the module tree but is still active! **URL:** \ **Category:** Rails\ **Created:** [May 15, 2008, 1:45am UTC](https://www.ruby-forum.com/t/a-copy-of-xx-has-been-removed-from-the-module-tree-but-is-still-active/137658 "2008-05-15T01:45:28Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![histrionics](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/h/dec6dc/32.png) [@histrionics](https://www.ruby-forum.com/u/histrionics)\ **Post date:** [May 15, 2008, 1:45am UTC](https://www.ruby-forum.com/t/a-copy-of-xx-has-been-removed-from-the-module-tree-but-is-still-active/137658/1 "2008-05-15T01:45:28Z")
I have a class in my /lib/ directory called tracker.rb It’s function is to receive an array of URLs and then perform 4 separate tasks on each URL Each of the 4 tasks gets it’s own thread. the class is called from my controller like: output = Tracker.go([array\_of\_urls]) Sometimes, when it hits an exception, instead of just dieing gracefully, my logs repeatedly display: A copy of Tracker has been removed from the module tree but is still active! After this happens, I have to reboot my development server before it will respond again. Any ideas how or why this is happening? Many thanks in advance for your insight. ---
**Author:** ![histrionics](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/h/dec6dc/32.png) [@histrionics](https://www.ruby-forum.com/u/histrionics)\ **Post date:** [May 15, 2008, 1:57am UTC](https://www.ruby-forum.com/t/a-copy-of-xx-has-been-removed-from-the-module-tree-but-is-still-active/137658/2 "2008-05-15T01:57:09Z")
Some more information: Usually, when I get this “A copy of Tracker has been removed from the module tree but is still active!” error, the exception raised is: wrong status line: “A\353\307\351\245}\243Z\213\364\232\3117\203w? \axcnv\313\356\230v\350\345\f\346\032e\262\2148\002$hZ\3163\362’\373N+e \3306\005’\3555\241\016\340\364\351\022+\333\340F\b \372\274\244\357\004\212\241\026\325)6v\0056\t\374\017\023N% \352\214\207\267R\_,\017e^\3321\327Gq\031! gG5\020\241\3565\356\200\3053\233\e\237\201\313\367\351/\327\206u.S \331z.\023\326’\2277\303\v\361\366a\270\304yf\376\315h \257\345A{\226\264\2352?\365\335\001\_Hl:F\2429\322\250\320k\250\002k \315\332\200\226\027P\374\335\363&\344\201#t\<\355\360.\331\365?(X=:5Y \240w6\365x\310\367\346\3368\315\350\>W\370\034\377\351Uk\001iOW.=\300k \036\351\307\323\303N\315\243\240\326eu\375AP, \326\243\036\263\306\250\313\335\254hm/H\254L\251\212= \334\022\363\366\251W\251UK\227W\373\215E\346\223\3316\343\375 \a \336\347\224\355\224u\017\tq\006\364\v\334\346O\355\205s \317\031\202\260\322’v?\2303\022\210\0062\002\300j\212mo^\254R\334=? \275\331cu’\320G\216\021\353Sb\223\234\037\262\200s\367\a” ---
**Author:** ![histrionics](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/h/dec6dc/32.png) [@histrionics](https://www.ruby-forum.com/u/histrionics)\ **Post date:** [May 15, 2008, 11:24am UTC](https://www.ruby-forum.com/t/a-copy-of-xx-has-been-removed-from-the-module-tree-but-is-still-active/137658/3 "2008-05-15T11:24:38Z")
On 15 May 2008, at 00:44, histrionics wrote: > output = Tracker.go([array\_of\_urls]) > > Sometimes, when it hits an exception, instead of just dieing > gracefully, my logs repeatedly display: I bet if you switched to production mode it would work. What I think is happening is: - request calls Tracker.go - Rails unloads loaded classes (since we’re in dev mode) - You threads continue to run trying to use classes that rails has unloaded. Chaos ensues. Fred ---
**Author:** ![histrionics](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/h/dec6dc/32.png) [@histrionics](https://www.ruby-forum.com/u/histrionics)\ **Post date:** [October 1, 2008, 9:56pm UTC](https://www.ruby-forum.com/t/a-copy-of-xx-has-been-removed-from-the-module-tree-but-is-still-active/137658/4 "2008-10-01T21:56:21Z")
Frederick C. wrote: > I bet if you switched to production mode it would work. What I think > is happening is: > > - request calls Tracker.go > - Rails unloads loaded classes (since we’re in dev mode) > - You threads continue to run trying to use classes that rails has > unloaded. Chaos ensues. > > Fred Bingo! Putting my application in production mode allowed me to make continual requests. It, however, doesn’t solve the problem though. Problem: I’ve got a module (AccessControl) in RAILS\_ROOT/lib that extends my controllers (which inherit from ResourceController) and adds functionality to AuthenticatedSystem. In development mode, this works fine via requests through the browser. However, once I try to consume the resources with ActiveResource, the first request succeeds and the next request fails with the following error: ArgumentError (A copy of AccessControl has been removed from the module tree but is still active!): /opt/local/lib/ruby/gems/1.8/gems/activesupport-2.1.1/lib/active\_support/dependencies.rb:250:in `load_missing_constant' /opt/local/lib/ruby/gems/1.8/gems/activesupport-2.1.1/lib/active_support/dependencies.rb:468:in`const\_missing’ /lib/access\_control.rb:122:in `controller\_target’ … I can’t figure out why this would work via the browser but not through ActiveResource. The only thing that’s different, if I understand it correctly, are the headers: Accept: application/xml Content-Type: application/xml Why would that make a difference? Not only that, the error is originating in the class it says it can’t find. Does anyone understand why this might be the case? ---
**Author:** ![histrionics](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/h/dec6dc/32.png) [@histrionics](https://www.ruby-forum.com/u/histrionics)\ **Post date:** [July 14, 2009, 10:20am UTC](https://www.ruby-forum.com/t/a-copy-of-xx-has-been-removed-from-the-module-tree-but-is-still-active/137658/5 "2009-07-14T10:20:51Z")
> ArgumentError (A copy of AccessControl has been removed from the module tree but is still active!): Check your environments/development.rb for config.cache\_classes and try setting it to true: config.cache\_classes = true #false It worked for me. It should also help, if you’re using RubyInline and have created some C/C++ methods in a class. In my case, I simply make a system call to run an external binary. You may also want to try and put your code in a gem, as it gets loaded every time you start the server, and doesn’t get unloaded. ---
**Author:** ![histrionics](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/h/dec6dc/32.png) [@histrionics](https://www.ruby-forum.com/u/histrionics)\ **Post date:** [October 1, 2008, 11:27pm UTC](https://www.ruby-forum.com/t/a-copy-of-xx-has-been-removed-from-the-module-tree-but-is-still-active/137658/6 "2008-10-01T23:27:17Z")
On Oct 1, 8:56 pm, Shawn P. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > Bingo! Putting my application in production mode allowed me to make > continual requests. It, however, doesn’t solve the problem though. The depedencies system has been confused: something is referencing an old copy of the module but that old copy should not be used anymore (since rails has reloaded a fresh copy). This can be caused by using require inappropriately ([http://spacevatican.org/2008/9/28/required-or-](http://spacevatican.org/2008/9/28/required-or-) not) or when things that shouldn’t be reloaded are reloaded (this can be changed by adding files to Dependencies.load\_once\_paths (see also [http://groups.google.com/group/rubyonrails-core/browse\_thread/thread/710868b1292c737f/9e39c0716569a355?lnk=gst&q=module+tree#9e39c0716569a355](http://groups.google.com/group/rubyonrails-core/browse_thread/thread/710868b1292c737f/9e39c0716569a355?lnk=gst&q=module+tree#9e39c0716569a355)). In your case I’d guess the latter - you’re extending something like a plugin (which isn’t reloaded between requests) with something that is reloaded between requests = trouble. Fred ---
**Author:** ![histrionics](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/h/dec6dc/32.png) [@histrionics](https://www.ruby-forum.com/u/histrionics)\ **Post date:** [August 10, 2009, 2:24pm UTC](https://www.ruby-forum.com/t/a-copy-of-xx-has-been-removed-from-the-module-tree-but-is-still-active/137658/7 "2009-08-10T14:24:32Z")
> A copy of Tracker has been removed from the module tree but is still > active! > > After this happens, I have to reboot my development server before it > will respond again. > > Any ideas how or why this is happening? Appears that it can occur when a plugin [which isn’t reloaded] keeps a reference to a normal class [which is reloaded]. ex: engines don’t reload, normal app does, if there was any intermingling boom! [http://groups.google.com/group/rubyonrails-core/browse\_thread/thread/9067bce01444fb24#](http://groups.google.com/group/rubyonrails-core/browse_thread/thread/9067bce01444fb24#) “a copy of OrderHelper has been removed from the module tree” I think that’s what happens to me, anyway. So much for the usefulness of dev. mode 🙂 -r ---
**Author:** ![histrionics](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/h/dec6dc/32.png) [@histrionics](https://www.ruby-forum.com/u/histrionics)\ **Post date:** [July 14, 2009, 10:24am UTC](https://www.ruby-forum.com/t/a-copy-of-xx-has-been-removed-from-the-module-tree-but-is-still-active/137658/8 "2009-07-14T10:24:16Z")
Sorry, forgot to mention. You need to restart the server after modifying the config file (and will have to restart it every time you make any changes to your classes, too).