[FTS] crash with lot of core.cbft files,fills up disk

Version: 4.5.0-1999 Enterprise Edition (build-1999)

Test run from testrunner:
./testrunner -i INI_FILE.ini get-cbcollect-info=True,get-logs=False,stop-on-failure=False,cluster=D:F:F,GROUP=P1 -t fts.stable_topology_fts.StableTopFTS.index_wiki,items=10000,analyzer=keyword,GROUP=P1

Crash logs:

https://s3.amazonaws.com/cb-customers/cbcrash/99/collectinfo-2016-04-04T223350-ns_1%40172.23.107.145.zip
https://s3.amazonaws.com/cb-customers/cbcrash/99/collectinfo-2016-04-04T223350-ns_1%40172.23.107.187.zip
https://s3.amazonaws.com/cb-customers/cbcrash/99/collectinfo-2016-04-04T223350-ns_1%40172.23.107.234.zip

Effect:

Once this crash happens , lot of core.cbft logs . fills up the disk and rest of test fails .