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authorRickard Green <[email protected]>2016-08-02 15:58:06 +0200
committerRickard Green <[email protected]>2016-08-29 16:26:24 +0200
commit9d0638216d35ca0f21c1eea20f8daa3992ac4f71 (patch)
treeb270d8f0226e88c376826584c4ea88ae377dff6f /lib/kernel
parent2fe03e832adb11c50bcfc62679cf17779b284124 (diff)
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Fix purge of code
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.
Diffstat (limited to 'lib/kernel')
-rw-r--r--lib/kernel/doc/src/code.xml10
1 files changed, 10 insertions, 0 deletions
diff --git a/lib/kernel/doc/src/code.xml b/lib/kernel/doc/src/code.xml
index d3611d6a03..21f8a2d54a 100644
--- a/lib/kernel/doc/src/code.xml
+++ b/lib/kernel/doc/src/code.xml
@@ -651,6 +651,11 @@ ok = code:finish_loading(Prepared),
<p>Purges the code for <c><anno>Module</anno></c>, that is, removes code
marked as old. If some processes still linger in the old code,
these processes are killed before the code is removed.</p>
+ <note><p>As of ERTS version 9.0, a process is only considered
+ to be lingering in the code if it has direct references to the code.
+ For more information see documentation of
+ <seealso marker="erts:erlang#check_process_code/3"><c>erlang:check_process_code/3</c></seealso>,
+ which is used in order to determine this.</p></note>
<p>Returns <c>true</c> if successful and any process is needed to
be killed, otherwise <c>false</c>.</p>
</desc>
@@ -661,6 +666,11 @@ ok = code:finish_loading(Prepared),
<desc>
<p>Purges the code for <c><anno>Module</anno></c>, that is, removes code
marked as old, but only if no processes linger in it.</p>
+ <note><p>As of ERTS version 9.0, a process is only considered
+ to be lingering in the code if it has direct references to the code.
+ For more information see documentation of
+ <seealso marker="erts:erlang#check_process_code/3"><c>erlang:check_process_code/3</c></seealso>,
+ which is used in order to determine this.</p></note>
<p>Returns <c>false</c> if the module cannot be purged because
of processes lingering in old code, otherwise <c>true</c>.</p>
</desc>