Average query throughput of UDF tests dropped by 99% on build 7.6.0-1538

http://172.23.123.237/#/timeline/Linux/n1ql/UDF/MOI 

Avg. Query Throughput (queries/sec), QU2, Singleton Unique Lookup, MOI, not_bounded

Avg. Query Throughput (queries/sec), QU2, Function calling another function, Singleton Unique Lookup, MOI, not_bounded

Avg. Query Throughput (queries/sec), QU3, Range Scan, MOI, not_bounded

Avg. Query Throughput (queries/sec), CU18, Range Scan with Limit and Offset (1K), Covering, MOI, not_bounded

There are 4 query changes related to UDF between 1451 and 1538.

http://changelog.build.couchbase.com/?product=couchbase-server&fromVersion=7.6.0&fromBuild=1451&toVersion=7.6.0&toBuild=1538&f_asterixdb=off&f_backup=off&f_cbas=off&f_cbas-core=off&f_cbas-ui=off&f_cbbs=off&f_cbft=off&f_cbftx=off&f_cbgt=off&f_chronicle=off&f_couchbase-cli=off&f_eventing=off&f_eventing-ee=off&f_forestdb=off&f_godbc=off&f_gomemcached=off&f_goxdcr=off&f_indexing=off&f_kv_engine=off&f_magma=off&f_n1fty=off&f_ns_server=off&f_plasma=off&f_platform=off&f_product-metadata=off&f_query=on&f_query-ee=off&f_query-ui=off&f_sigar=off&f_testrunner=off&f_tlm=off&f_voltron=off

Commit: 76a40fd2cfb70716a7fb1513c505f5f62658445c in build: couchbase-server-7.6.0-1538

Revert "MB-58648: Revise handling of profile info for subqueries in Inline UDFs"

Commit: a60eaa445972087b9c289991adfc822a9690ebdb in build: couchbase-server-7.6.0-1536

MB-58648: Revise handling of profile info for subqueries in Inline UDFs

Commit: 184d81e5504706fe8390fff701690e3543a69a48 in build: couchbase-server-7.6.0-1525

MB-58479 Use the same mutex for fields shared among multiple contexts

Commit: d77825fc60448238bb8f599004926d0009d9d56b in build: couchbase-server-7.6.0-1510

MB-58479: Fix fatal errors on concurrent Inline function execution