Default CompactionOptionsUniversal::reduce_file_locking to be true (#14329)

Summary:
**Context/Summary:**

Internal adoption has demonstrated stability and measurable improvements of this feature without much cost so we can turn it on by default. Eventually we'd like to remove this configuration and make this an expected behavior.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/14329

Test Plan: Existing unit test

Reviewed By: mszeszko-meta

Differential Revision: D93210059

Pulled By: hx235

fbshipit-source-id: 04f77954e6624c8e60a2db030eb19eb341dd0fcf

include/rocksdb/universal_compaction.h

@@ -111,8 +111,6 @@ class CompactionOptionsUniversal {
   // Default: false
   bool incremental;
 
-  // EXPERIMENTAL
-  //
   // If true, auto universal compaction picking will adjust to minimize locking
   // of input files when bottom priority compactions are waiting to run. This
   // can increase the likelihood of existing L0s being selected for compaction,
@@ -120,7 +118,7 @@ class CompactionOptionsUniversal {
   // the overrall write amplification and compaction load on low priority
   // threads.
   //
-  // Default: false (disabled)
+  // Default: true (enabled)
   //
   // This options does not apply to manual compactions.
   //
@@ -142,7 +140,7 @@ class CompactionOptionsUniversal {
         stop_style(kCompactionStopStyleTotalSize),
         allow_trivial_move(false),
         incremental(false),
-        reduce_file_locking(false) {}
+        reduce_file_locking(true) {}
 
   bool operator==(const CompactionOptionsUniversal& rhs) const = default;
 };

unreleased_history/behavior_changes/reduce_file_locking_default_true.md

@@ -0,0 +1 @@
+Change the default value of `CompactionOptionsUniversal::reduce_file_locking` from `false` to `true` to improve write stall and reduce read regression