SOLR-13130: during the ResponseBuilder.STAGE_GET_FIELDS directly copy string bytes and avoid creating String Objects

solr/CHANGES.txt

@@ -183,6 +183,8 @@ Optimizations
   This gives a lower absolute score but doesn't affect ordering, as this is a constant factor which is the same 
   for every document. Use LegacyBM25SimilarityFactory if you need the old 6.x/7.x scoring. See also upgrade notes (janhoy)
 
+* SOLR-13130: during the ResponseBuilder.STAGE_GET_FIELDS directly copy string bytes and avoid creating String Objects (noble)
+
 Other Changes
 ----------------------
 

solr/core/src/java/org/apache/solr/handler/component/HttpShardHandler.java

@@ -36,6 +36,7 @@ import java.util.function.Predicate;
 import org.apache.solr.client.solrj.SolrRequest;
 import org.apache.solr.client.solrj.SolrResponse;
 import org.apache.solr.client.solrj.SolrServerException;
+import org.apache.solr.client.solrj.impl.BinaryResponseParser;
 import org.apache.solr.client.solrj.impl.Http2SolrClient;
 import org.apache.solr.client.solrj.impl.LBSolrClient;
 import org.apache.solr.client.solrj.request.QueryRequest;
@@ -53,6 +54,7 @@ import org.apache.solr.common.params.CommonParams;
 import org.apache.solr.common.params.ModifiableSolrParams;
 import org.apache.solr.common.params.ShardParams;
 import org.apache.solr.common.params.SolrParams;
+import org.apache.solr.common.util.JavaBinCodec;
 import org.apache.solr.common.util.NamedList;
 import org.apache.solr.common.util.StrUtils;
 import org.apache.solr.core.CoreDescriptor;
@@ -62,6 +64,8 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.slf4j.MDC;
 
+import static org.apache.solr.handler.component.ShardRequest.PURPOSE_GET_FIELDS;
+
 public class HttpShardHandler extends ShardHandler {
   
   /**
@@ -132,6 +136,13 @@ public class HttpShardHandler extends ShardHandler {
     return urls;
   }
 
+  private static final BinaryResponseParser READ_STR_AS_CHARSEQ_PARSER = new BinaryResponseParser() {
+    @Override
+    protected JavaBinCodec createCodec() {
+      return new JavaBinCodec(null, stringCache).setReadStringAsCharSeq(true);
+    }
+  };
+
   @Override
   public void submit(final ShardRequest sreq, final String shard, final ModifiableSolrParams params) {
     // do this outside of the callable for thread safety reasons
@@ -158,6 +169,9 @@ public class HttpShardHandler extends ShardHandler {
         SolrRequestInfo requestInfo = SolrRequestInfo.getRequestInfo();
         if (requestInfo != null) req.setUserPrincipal(requestInfo.getReq().getUserPrincipal());
 
+        if (sreq.purpose == PURPOSE_GET_FIELDS) {
+          req.setResponseParser(READ_STR_AS_CHARSEQ_PARSER);
+        }
         // no need to set the response parser as binary is the default
         // req.setResponseParser(new BinaryResponseParser());
 

solr/solrj/src/java/org/apache/solr/client/solrj/impl/BinaryResponseParser.java

@@ -32,7 +32,7 @@ import java.io.Reader;
 public class BinaryResponseParser extends ResponseParser {
   public static final String BINARY_CONTENT_TYPE = "application/octet-stream";
 
-  private JavaBinCodec.StringCache stringCache;
+  protected JavaBinCodec.StringCache stringCache;
 
   public BinaryResponseParser setStringCache(JavaBinCodec.StringCache cache) {
     this.stringCache = cache;
@@ -47,13 +47,17 @@ public class BinaryResponseParser extends ResponseParser {
   @Override
   public NamedList<Object> processResponse(InputStream body, String encoding) {
     try {
-      return (NamedList<Object>) new JavaBinCodec(null,stringCache).unmarshal(body);
+      return (NamedList<Object>) createCodec().unmarshal(body);
     } catch (IOException e) {
       throw new SolrException(SolrException.ErrorCode.SERVER_ERROR, "parsing error", e);
 
     }
   }
 
+  protected JavaBinCodec createCodec() {
+    return new JavaBinCodec(null, stringCache);
+  }
+
   @Override
   public String getContentType() {
     return BINARY_CONTENT_TYPE;