Merge pull request #4656 from karknu/karknu/churn_20_m

Be less aggresive when churning peers
IntersectMBO · Aug 24, 2023 · a9ca17b · a9ca17b
2 parents f54839c + 7b697fd
commit a9ca17b
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diff --git a/ouroboros-network/CHANGELOG.md b/ouroboros-network/CHANGELOG.md
@@ -4,7 +4,15 @@
 
 ### Breaking changes
 
-- Removes `updatePeerSharing` from `KnownPeers` module API
+### Non-breaking changes
+
+* Less aggresive churning of established and known peers.
+
+## 0.9.1.0 -- 2023-08-22
+
+### Breaking changes
+
+* Removes `updatePeerSharing` from `KnownPeers` module API
 
 ### Non-breaking changes
 

diff --git a/ouroboros-network/src/Ouroboros/Network/PeerSelection/Churn.hs b/ouroboros-network/src/Ouroboros/Network/PeerSelection/Churn.hs
@@ -152,15 +152,22 @@ peerChurnGovernor tracer deadlineChurnInterval bulkChurnInterval
       -- Forget the worst performing non-active peers.
       atomically $ modifyTVar peerSelectionVar (\targets -> targets {
           targetNumberOfRootPeers =
-            decrease (targetNumberOfRootPeers base)
+            decrease (targetNumberOfRootPeers base - targetNumberOfEstablishedPeers base)
+            + targetNumberOfEstablishedPeers base
         , targetNumberOfKnownPeers =
-            decrease (targetNumberOfKnownPeers base)
+            decrease (targetNumberOfKnownPeers base - targetNumberOfEstablishedPeers base)
+            + targetNumberOfEstablishedPeers base
         , targetNumberOfEstablishedPeers =
-            decrease (targetNumberOfEstablishedPeers base)
+            decrease (targetNumberOfEstablishedPeers base - targetNumberOfActivePeers base)
+            + targetNumberOfActivePeers base
         , targetNumberOfKnownBigLedgerPeers =
-            decrease (targetNumberOfKnownBigLedgerPeers base)
+            decrease (targetNumberOfKnownBigLedgerPeers base -
+                      targetNumberOfEstablishedBigLedgerPeers base)
+            + targetNumberOfEstablishedBigLedgerPeers base
         , targetNumberOfEstablishedBigLedgerPeers =
-            decrease (targetNumberOfEstablishedBigLedgerPeers base)
+            decrease (targetNumberOfEstablishedBigLedgerPeers base -
+                      targetNumberOfActiveBigLedgerPeers base)
+            + targetNumberOfActiveBigLedgerPeers base
         })
 
       -- Give the governor time to properly demote them.
@@ -202,9 +209,9 @@ peerChurnGovernor tracer deadlineChurnInterval bulkChurnInterval
     shortDelay :: StdGen -> DiffTime -> m StdGen
     shortDelay = fuzzyDelay' bulkChurnInterval 60
 
-    -- Replace 20% or at least on peer every churnInterval.
+    -- Replace 20% or at least one peer every churnInterval.
     decrease :: Int -> Int
-    decrease v = v  - max 1 (v `div` 5)
+    decrease v = max 0 $ v  - max 1 (v `div` 5)