SOLR-10857: Solr loads UNLOADed core on request.

solr/CHANGES.txt

@@ -397,6 +397,13 @@ Other Changes
 * SOLR-10761: Switch trie numeric/date fields to points in data-driven-enabled example and test schemas.
   (Steve Rowe)
 
+==================  6.6.1 ==================
+
+Bug Fixes
+----------------------
+
+* SOLR-10857: standalone Solr loads UNLOADed core on request (Erick Erickson, Mikhail Khludnev)
+
 ==================  6.6.0 ==================
 
 Consult the LUCENE_CHANGES.txt file for additional, low level, changes in this release.

solr/core/src/java/org/apache/solr/core/CoreContainer.java

@@ -1285,6 +1285,8 @@ public class CoreContainer {
 
     boolean close = solrCores.isLoadedNotPendingClose(name);
     SolrCore core = solrCores.remove(name);
+
+    solrCores.removeCoreDescriptor(cd);
     coresLocator.delete(this, cd);
     if (core == null) {
       // transient core
@@ -1298,8 +1300,8 @@ public class CoreContainer {
     if (zkSys.getZkController() != null) {
       // cancel recovery in cloud mode
       core.getSolrCoreState().cancelRecovery();
-      if (core.getCoreDescriptor().getCloudDescriptor().getReplicaType() == Replica.Type.PULL
-          || core.getCoreDescriptor().getCloudDescriptor().getReplicaType() == Replica.Type.TLOG) {
+      if (cd.getCloudDescriptor().getReplicaType() == Replica.Type.PULL
+          || cd.getCloudDescriptor().getReplicaType() == Replica.Type.TLOG) {
         // Stop replication if this is part of a pull/tlog replica before closing the core
         zkSys.getZkController().stopReplicationFromLeader(name);
       }
@@ -1319,9 +1321,6 @@ public class CoreContainer {
         throw new SolrException(ErrorCode.SERVER_ERROR, "Error unregistering core [" + name + "] from cloud state", e);
       }
     }
-    if (deleteInstanceDir) { // we aren't going to reload this if we delete the instance dir.
-      solrCores.removeCoreDescriptor(cd);
-    }
   }
 
   public void rename(String name, String toName) {

solr/core/src/test/org/apache/solr/handler/admin/CoreAdminHandlerTest.java

@@ -27,10 +27,12 @@ import com.carrotsearch.randomizedtesting.rules.SystemPropertiesRestoreRule;
 import org.apache.commons.io.FileUtils;
 import org.apache.lucene.util.Constants;
 import org.apache.solr.SolrTestCaseJ4;
+import org.apache.solr.client.solrj.SolrQuery;
 import org.apache.solr.client.solrj.embedded.JettySolrRunner;
 import org.apache.solr.client.solrj.impl.HttpSolrClient;
 import org.apache.solr.client.solrj.request.CoreAdminRequest;
 import org.apache.solr.client.solrj.request.CoreStatus;
+import org.apache.solr.client.solrj.response.QueryResponse;
 import org.apache.solr.common.SolrException;
 import org.apache.solr.common.SolrInputDocument;
 import org.apache.solr.common.params.CoreAdminParams;
@@ -282,6 +284,56 @@ public class CoreAdminHandlerTest extends SolrTestCaseJ4 {
 
   }
 
+  @Test
+  public void testUnloadForever() throws Exception  {
+    File solrHomeDirectory = new File(initCoreDataDir, getClass().getName() + "-corex-"
+        + System.nanoTime());
+    solrHomeDirectory.mkdirs();
+    copySolrHomeToTemp(solrHomeDirectory, "corex");
+    File corex = new File(solrHomeDirectory, "corex");
+    FileUtils.write(new File(corex, "core.properties"), "", StandardCharsets.UTF_8);
+    JettySolrRunner runner = new JettySolrRunner(solrHomeDirectory.getAbsolutePath(), buildJettyConfig("/solr"));
+    runner.start();
+
+    try (HttpSolrClient client = getHttpSolrClient(runner.getBaseUrl() + "/corex")) {
+      client.setConnectionTimeout(SolrTestCaseJ4.DEFAULT_CONNECTION_TIMEOUT);
+      client.setSoTimeout(SolrTestCaseJ4.DEFAULT_CONNECTION_TIMEOUT);
+      SolrInputDocument doc = new SolrInputDocument();
+      doc.addField("id", "123");
+      client.add(doc);
+      client.commit();
+    }
+
+    try (HttpSolrClient client = getHttpSolrClient(runner.getBaseUrl() + "/corex")) {
+      client.setConnectionTimeout(SolrTestCaseJ4.DEFAULT_CONNECTION_TIMEOUT);
+      client.setSoTimeout(SolrTestCaseJ4.DEFAULT_CONNECTION_TIMEOUT);
+      QueryResponse result = client.query(new SolrQuery("id:*"));
+      assertEquals(1,result.getResults().getNumFound());
+    }
+    
+    try (HttpSolrClient client = getHttpSolrClient(runner.getBaseUrl().toString())) {
+      client.setConnectionTimeout(SolrTestCaseJ4.DEFAULT_CONNECTION_TIMEOUT);
+      client.setSoTimeout(SolrTestCaseJ4.DEFAULT_CONNECTION_TIMEOUT);
+      CoreAdminRequest.Unload req = new CoreAdminRequest.Unload(false);
+      req.setDeleteInstanceDir(false);//random().nextBoolean());
+      req.setCoreName("corex");
+      req.process(client);
+    }
+
+    try (HttpSolrClient client = getHttpSolrClient(runner.getBaseUrl() + "/corex")) {
+      client.setConnectionTimeout(SolrTestCaseJ4.DEFAULT_CONNECTION_TIMEOUT);
+      client.setSoTimeout(SolrTestCaseJ4.DEFAULT_CONNECTION_TIMEOUT*1000);
+      QueryResponse result = client.query(new SolrQuery("id:*"));
+      //assertEquals(1,result.getResults().getNumFound());
+      fail("expect 404");
+    }catch(Exception e){
+      e.printStackTrace();
+    }
+    finally{
+      runner.stop();
+    }
+  }
+  
   @Test
   public void testDeleteInstanceDirAfterCreateFailure() throws Exception  {
     assumeFalse("Ignore test on windows because it does not delete data directory immediately after unload", Constants.WINDOWS);