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2016-09-15Merge branch 'maint'Björn Gustavsson
* maint: erts: Add nif_SUITE:t_on_load erts: Improve nif_SUITE:upgrade test Don't leak old code when loading a modules with an on_load function Conflicts: erts/preloaded/ebin/erts_code_purger.beam erts/preloaded/ebin/erts_internal.beam erts/preloaded/src/erts_code_purger.erl
2016-09-14Don't leak old code when loading a modules with an on_load functionBjörn Gustavsson
Normally, calling code:delete/1 before re-loading the code for a module is unnecessary but causes no problem. But there will be be problems if the new code has an on_load function. Code with an on_load function will always be loaded as old code to allowed it to be easily purged if the on_load function would fail. If the on_load function succeeds, the old and current code will be swapped. So in the scenario where code:delete/1 has been called explicitly, there is old code but no current code. Loading code with an on_load function will cause the reference to the old code to be overwritten. That will at best cause a memory leak, and at worst an emulator crash (especially if NIFs are involved). To avoid that situation, we will put the code with the on_load function in a special, third slot in Module. ERL-240
2016-08-31Avoid selective receive in code-purger processRickard Green
The code purger process handles vast amounts of messages when there are lots of processes alive. A single message in the message queue that does not match will in such cases cause lots of extra work. The code purger process now always picks the first message in the message queue, and by this avoid this extra work.
2016-08-31Remove old purge strategyRickard Green
2016-08-29Fix purge of codeRickard Green
Ensure that we cannot get any dangling pointers into code that has been purged. This is done by a two phase purge. At first phase all fun entries pointing into the code to purge are marked for purge. All processes trying to call these funs will be suspended and by this we avoid getting new direct references into the code. When all processes has been checked, these processes are resumed. The new purge strategy now also completely ignore the existence of indirect references to the code (funs). If such exist, they will cause bad fun exceptions to the caller, but will not prevent a soft purge or cause a kill of a process having such live references during a hard purge. This since it is impossible to give any guarantees that no processes in the system have such indirect references. Even when the system is completely clean from such references, new ones can appear via distribution and/or disk.
2016-08-26Reclaim literal area after purge has completedRickard Green
2016-01-25erts: Fix harmless dialyzer warningsSverker Eriksson
2016-01-19erts: Ignore unexpected messages to erts_code_purgerSverker Eriksson
2016-01-13erts: Optimize erlang:check_process_codeSverker Eriksson
by ignoring literals. erts_internal:check_process_code will be called again anyway (with option {copy_literals, true}) before the module is actually purged. No need to check literals twice.
2016-01-13erts: Make copy_literals more fail safeSverker Eriksson
* Same process must do enable-disable. * System process will force it and never get 'aborted'
2016-01-13erts: Move copy_literals/2 from erlang to erts_internalSverker Eriksson
as it's not a public interface.
2016-01-13erts: Make erlang:purge_module/1 safeSverker Eriksson
Problem: erlang:purge_module/1 is not safe in the sense that very bad things may happen if the code to be purged is still referred to by live processes. Introduce erts_internal:purge_module which is the same as the old erlang:purge_module BIF (except it returns false if no such old module). Implement erlang:purge_module in Erlang and let it invoke erts_code_purger for safe purging where all clogging processes first are killed.
2016-01-13erts: Refactor code:purge/1 and code:soft_purge/1Sverker Eriksson
by moving code from code_server to erts_code_purger. This is more or less a copy-paste from code_server.erl to erts_code_purger.erl. All the inner mechanics of code:purge/1 and code:soft_purge/1 are unchanged.
2016-01-13erts: Introduce erts_code_purgerSverker Eriksson
as a system process with preloaded code.