IIRC, it was really just for testing.
+1

Patch to remove nrtMode. This also removes TestNonNRTOpen, TestArbitraryIndexDir and TestReplicationHandler.testNoWriter.

TestNonNRTOpen is not needed anymore. We may need another test to replace TestArbitraryIndexDir. I am not yet sure about TestReplicationHandler.testNoWriter.

===================================================================
--- solr/core/src/java/org/apache/solr/core/SolrConfig.java     (revision 1648550)
+++ solr/core/src/java/org/apache/solr/core/SolrConfig.java     (revision )
@@ -192,7 +192,6 @@
       defaultIndexConfig = mainIndexConfig = null;
       indexConfigPrefix = "indexConfig";
     }
-    nrtMode = getBool(indexConfigPrefix+"/nrtMode", true);
     // Parse indexConfig section, using mainIndex as backup in case old config is used
     indexConfig = new SolrIndexConfig(this, "indexConfig", mainIndexConfig);
 

this change should follow the same pattern we use anytime we stop supporting a config option:

• check config to see if it's specified, and if so log a warning
• commit & backport
• update trunk to change warning log to fatal error & note it in X.0 (6.0 in this case) "upgrading" instructions.

(this is why methods like SolrIndexConfig.assertWarnOrFail exist .. perhaps that method should be promoted to protected in Config.java?)

Thanks Hoss.

I moved the assertWarnOrFail method to Config and I used it for this change. This patch is for branch_5x. On trunk I will change the assert to throw an exception.

This patch restores TestArbitraryIndexDir and modified it to use core reload instead of commit which will make it work fine without the need to turn off NRT mode.

The TestReplicationHandler.testNoWriter is a weird test. An IW is always opened and the assumption in the test is wrong. I think we can safely remove this test.

Commit 1649810 from shalin@apache.org in branch 'dev/trunk'
[ https://svn.apache.org/r1649810 ]

SOLR-6897: Nuke non-NRT mode from code and configuration

Commit 1649812 from shalin@apache.org in branch 'dev/branches/branch_5x'
[ https://svn.apache.org/r1649812 ]

SOLR-6897: Nuke non-NRT mode from code and configuration

Commit 1649814 from shalin@apache.org in branch 'dev/trunk'
[ https://svn.apache.org/r1649814 ]

SOLR-6897: Fix wrong assert

Commit 1649815 from shalin@apache.org in branch 'dev/branches/branch_5x'
[ https://svn.apache.org/r1649815 ]

SOLR-6897: Fix wrong assert

Commit 1649816 from shalin@apache.org in branch 'dev/trunk'
[ https://svn.apache.org/r1649816 ]

SOLR-6897: Throw fatal error if nrtMode is present in solrconfig on 6.0. Added note to upgrade section.

This is fixed.

I added a test on trunk in TestBadConfig.java which asserts that an error is thrown if nrtMode is specified in solrconfig.xml. Added upgrade notes to 5.0 and 6.0 sections.

Bulk close after 5.0 release.