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| -rw-r--r-- | system/doc/reference_manual/code_loading.xml | 21 |
1 files changed, 17 insertions, 4 deletions
diff --git a/system/doc/reference_manual/code_loading.xml b/system/doc/reference_manual/code_loading.xml index 23871dfa83..b5b5704df5 100644 --- a/system/doc/reference_manual/code_loading.xml +++ b/system/doc/reference_manual/code_loading.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>2003</year><year>2013</year> + <year>2003</year><year>2014</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> @@ -121,9 +121,22 @@ loop() -> <title>Running a function when a module is loaded</title> <warning> - <p>We recommend that the feature described in this section is to - be used only for loading NIF libraries. For other usages this - feature should be considered experimental.</p> + <p>The <c>on_load</c> feature should be considered experimental + as there are a number of known weak points in current semantics + which therefore might also change in future releases:</p> + <list> + <item><p>Doing external call in on_load to the module itself + leads to deadlock.</p></item> + <item><p>At module upgrade, other processes calling the module + get suspended waiting for on_load to finish. This can be very bad + for applications with demands on realtime characteristics.</p></item> + <item><p>At module upgrade, no rollback is done if the on_load function fails. + The system will be left in a bad limbo state without any working + and reachable instance of the module.</p></item> + </list> + <p>The problems with module upgrade described above could be fixed in future + releases by changing the behaviour to not make the module reachable until + after the on_load function has successfully returned.</p> </warning> <p>The <c>-on_load()</c> directive names a function that should |