[GitHub] [iceberg] kbendick commented on a change in pull request #3977: [Core][Spark][Flink] Change partitioned fanout/delta writers map to caffine cache

[GitBox <gi...@apache.org>]

kbendick commented on a change in pull request #3977:
URL: https://github.com/apache/iceberg/pull/3977#discussion_r796157999



##########
File path: core/src/main/java/org/apache/iceberg/io/PartitionedFanoutWriter.java
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@@ -19,19 +19,52 @@
 
 package org.apache.iceberg.io;
 
+import com.github.benmanes.caffeine.cache.Cache;
+import com.github.benmanes.caffeine.cache.Caffeine;
 import java.io.IOException;
+import java.io.UncheckedIOException;
 import java.util.Map;
+import java.util.concurrent.ConcurrentMap;
+import java.util.concurrent.TimeUnit;
 import org.apache.iceberg.FileFormat;
 import org.apache.iceberg.PartitionKey;
 import org.apache.iceberg.PartitionSpec;
-import org.apache.iceberg.relocated.com.google.common.collect.Maps;
+import org.apache.iceberg.TableProperties;
+import org.apache.iceberg.util.PropertyUtil;
+import org.apache.iceberg.util.Tasks;
 
 public abstract class PartitionedFanoutWriter<T> extends BaseTaskWriter<T> {
-  private final Map<PartitionKey, RollingFileWriter> writers = Maps.newHashMap();
+  private Cache<PartitionKey, RollingFileWriter> writers;
 
   protected PartitionedFanoutWriter(PartitionSpec spec, FileFormat format, FileAppenderFactory<T> appenderFactory,
-                          OutputFileFactory fileFactory, FileIO io, long targetFileSize) {
+                          OutputFileFactory fileFactory, FileIO io,
+                          long targetFileSize, Map<String, String> properties) {
     super(spec, format, appenderFactory, fileFactory, io, targetFileSize);
+    int writersCacheSize = PropertyUtil.propertyAsInt(
+        properties,
+        TableProperties.PARTITIONED_FANOUT_WRITERS_CACHE_SIZE,
+        TableProperties.PARTITIONED_FANOUT_WRITERS_CACHE_SIZE_DEFAULT);
+    long evictionTimeout = PropertyUtil.propertyAsLong(
+        properties,
+        TableProperties.PARTITIONED_FANOUT_WRITERS_CACHE_EVICT_MS,
+        TableProperties.PARTITIONED_FANOUT_WRITERS_CACHE_EVICT_MS_DEFAULT);
+    initWritersCache(writersCacheSize, evictionTimeout);
+  }
+
+  private synchronized void initWritersCache(int writersCacheSize, long evictionTimeout) {
+    if (writers == null) {
+      writers = Caffeine.newBuilder()
+          .maximumSize(writersCacheSize)
+          .expireAfterAccess(evictionTimeout, TimeUnit.MILLISECONDS)
+          .removalListener((key, value, cause) -> {

Review comment:
       This would instantiate a thread pool and evicted items would enter a queue to go in there.
   
   So I believe the removalListener would be run in a background thread instantiated by Cafffeine.




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