Garbage collection of unused chunks should now be faster.

h2/src/docsrc/html/changelog.html

@@ -21,6 +21,8 @@ Change Log
 
 <h2>Next Version (unreleased)</h2>
 <ul>
+<li>Garbage collection of unused chunks should now be faster.
+</li>
 <li>Prevent people using unsupported combination of auto-increment columns and clustering mode.
 </li>
 <li>Support for DB2 time format, patch by Niklas Mehner

h2/src/main/org/h2/mvstore/MVStore.java

@@ -279,6 +279,8 @@ public class MVStore {
 
     private long lastTimeAbsolute;
 
+    private long lastFreeUnusedChunks;
+
     /**
      * Create and open the store.
      *
@@ -1051,13 +1053,16 @@ public class MVStore {
     }
 
     private long storeNowTry() {
-        freeUnusedChunks();
-
+        long time = getTimeSinceCreation();
+        int freeDelay = retentionTime / 10;
+        if (time >= lastFreeUnusedChunks + freeDelay) {
+            lastFreeUnusedChunks = time;
+            freeUnusedChunks();
+        }
         int currentUnsavedPageCount = unsavedMemory;
         long storeVersion = currentStoreVersion;
         long version = ++currentVersion;
         setWriteVersion(version);
-        long time = getTimeSinceCreation();
         lastCommitTime = time;
         retainChunk = null;