http://dev.clojure.org/jira This file is an XML representation of an issue en-us 4.4 649 25-07-2011 http://dev.clojure.org/jira/browse/CLJ-1104 Clojure <p>On 1.4 and latest master:</p> <p>user&gt; (defn ten [] 10)<br/> #'user/ten<br/> user&gt; (doall (pmap #(with-redefs [ten (fn [] %)] (ten)) (range 20 100)))<br/> (20 21 22 23 24 25 34 27 28 29 30 31 32 33 34 35 36 37 38 39 39 35 42 43 44 45 48 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 79 87 88 89 90 91 92 93 94 95 97 92 98 99)<br/> user&gt; (ten)<br/> 79</p> <p>Not sure if this is a bug per se, but the doc doesn't mention lack of concurrency safety and my expectation was that the original value would always be restored after any (arbitrarily interleaved) sequence of with-redefs calls. </p> Mac OS, Java 6 CLJ-1104

Concurrent with-redefs do not unwind properly, leaving a var permanently changed

Enhancement Minor Open Unresolved Unassigned Jason Wolfe Wed, 7 Nov 2012 17:46:19 -0600 Fri, 21 Dec 2012 23:05:10 -0600 Release 1.4 Release 1.5 Approved Backlog 0 0 <p>The with-redefs doc (v1.4.0) says "These temporary changes will be visible in all threads." That sounds non-thread-safe to me.</p> <p>In general, changes to var root bindings are not thread safe.</p> <p>As I understand it, with-redefs is mainly used in test suites to mock out vars. It was introduced when vars became static by default and a lot of testsuites had been using binding for mocking. Maybe the docstring should be amended with something along the lines of: When using this you have to ensure that only a single thread is interacting with redef'd vars.</p> <p>Behavior find as is, doc string change would be fine.</p> <p>Patch clj-1104-doc-unsafety-of-concurrent-with-redefs-v1.txt dated Nov 25 2012 updates doc string of with-redefs to make it clear that concurrent use is unsafe.</p> Approval Vetted Global Rank Patch Code