indexwriter shuts down

["j.s." <js...@brandeis.edu>]

hi

i am running a stand alone solr instance 7.3.1 that has been giving me 
errors recently. these are from an application log (not solr), but they 
appear to show that somehow the indexwriter gets shut down and show's over!

i am sure there are more clues in the logs, but i'm not sure where to 
find them. is this osme kinda known issue ... ?

any suggestions on ways forward? thx.


Error while indexing file with document id 
mod_assign-activity-88477-solrfile25611739: Exception writing document 
id mod_assign-activity-88477-solrfile25611739 to the index; possible 
analysis error$
Error while indexing file with document id 
mod_assign-activity-88477-solrfile25611741: Exception writing document 
id mod_assign-activity-88477-solrfile25611741 to the index; possible 
analysis error.
   Processed 4515 records containing 4376 documents, in 377.9 seconds.
... used 195019 dbqueries
... used 405.2789349556 seconds
Scheduled task failed: Global search indexing 
(core\task\search_index_task),org.apache.lucene.store
.AlreadyClosedException: this IndexWriter is closed
         at 
org.apache.lucene.index.IndexWriter.ensureOpen(IndexWriter.java:897)
         at 
org.apache.lucene.index.IndexWriter.ensureOpen(IndexWriter.java:911)
         at 
org.apache.lucene.index.IndexWriter.commit(IndexWriter.java:3422)
         at 
org.apache.solr.update.DirectUpdateHandler2.commit(DirectUpdateHandler2.java:684)

(and on and on ...)