Make ActiveSupport::Logger Fiber-safe

Use Fiber.current.__id__ in ActiveSupport::Logger#local_level= in order
to make log level local to Ruby Fibers in addition to Threads.

1 files changed, 32 insertions, 0 deletions

diff --git a/activesupport/CHANGELOG.md b/activesupport/CHANGELOG.md
index d56d4c22de..5d6bb7a0b3 100644
--- a/activesupport/CHANGELOG.md
+++ b/activesupport/CHANGELOG.md
@@ -1,3 +1,35 @@
+*   Make ActiveSupport::Logger Fiber-safe. Fixes #36752.
+
+    Use `Fiber.current.__id__` in `ActiveSupport::Logger#local_level=` in order
+    to make log level local to Ruby Fibers in addition to Threads.
+
+    Example:
+
+        logger = ActiveSupport::Logger.new(STDOUT)
+        logger.level = 1
+        p "Main is debug? #{logger.debug?}"
+
+        Fiber.new {
+          logger.local_level = 0
+          p "Thread is debug? #{logger.debug?}"
+        }.resume
+
+        p "Main is debug? #{logger.debug?}"
+
+    Before:
+
+        Main is debug? false
+        Thread is debug? true
+        Main is debug? true
+
+    After:
+
+        Main is debug? false
+        Thread is debug? true
+        Main is debug? false
+
+    *Alexander Varnin*
+
 *   Allow the `on_rotation` proc used when decrypting/verifying a message to be
     passed at the constructor level.