Changes between Version 3 and Version 4 of Group_Lock

Timestamp:

Feb 25, 2013 9:54:27 AM (11 years ago)

Author:

bennylp

Comment:

--

Group_Lock

@@ -157 +157 @@
 If you after this find out that the leaking reference is caused by timer, you can enable timer heap debugging by setting {{{PJ_TIMER_DEBUG}}} to non-zero and call {{{pj_timer_heap_dump()}}} to dump the state of the timer heap including information about the source file and line number of code that registered currently active timer entries.
 
+== Notes ==
+
+=== Deadlock When Synchronizing to More Than One External Locks === #deadlock-externals
+
+Adding more than one external locks to a group lock may introduce deadlock potential. Consider the following example.
+
+ 1. External lock EA and EB (read: external A and B) are added to group lock G, resulting in group lock's chain: {{{ {EA --> EB --> G} }}}
+ 2. Thread 1 locks EA then G. The lock order then is: {{{ EA --> { EA --> EB --> G } }}}
+ 3. Thread 2 locks EB then G. The lock order then is: {{{ EB --> { EA --> EB --> G } }}}
+ 4. The lock orders in 2 and 3 are not uniform, potentially causing deadlock.
+
+
+
+
 {{{
 #!html