Add CHANGES note for [GL #3977]

diff --git a/CHANGES b/CHANGES
index 9fc27d98b2e17c03f0377cf971f895e6e8eb39ed..c612496020dc067531c653569c5ef2aaf00c41dd 100644 (file)
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,13 @@
+6154.  [func]          Add spinlock implementation.  The spinlock is much
+                       smaller (8 bytes) than pthread_mutex (40 bytes), so
+                       it can be easily embedded into objects for more
+                       fine-grained locking (per-object vs per-bucket).
+
+                       On the other hand, the spinlock is unsuitable for
+                       situations where the lock might be held for a long
+                       time as it keeps the waiting threads in a spinning
+                       busy loop. [GL #3977]
+
 6153.  [bug]           Fix the streaming protocols (TCP, TLS) shutdown
                        sequence. [GL #4011]