Add backpressure to InMemoryExchange
Run all tests in parallel by default

Annotate all tests that use @BeforeMethod with singleThreaded=true
Fix planning issue when using DISTICT aggregations in HAVING clause

Planning fails with a "Multiple entries with same key" error
Add test for HAVING with DISTINCT aggregations
Fix division by zero in some aggregations

Fix both VarianceAggregation and ApproximateAverageAggregation
Remove potential deadlock with broken connectors

Replace synchronized lock with a custom lock with timeout support

For close and updateSource stage change and then attempt to acquire
lock.  If lock is acquired, process change; otherwise lock holder
will process change before releasing lock.

For close, if lock can not be acquired, interrupt lock holder.
Remove obsolete test logging configuration
Fix logging for S3 tests
Support write and retry in PrestoS3FileSystem
Add tests for S3 table creation
Allow using IterableTransformer on arrays
Add error codes to categorize failures
Add error codes for Hive
Remove unused property
Global split assignment
Fix null values for DatabaseMetaData.getColumns
Remove SetThreadName as it consumes a significant amount of cpu time
Fix bug in NodeScheduler

HashMap was being recreated on every iteration of loop
Add release notes for 0.61
Revert "Fix bug in NodeScheduler"

This reverts commit 25f921fb81be4d23a68e52634ed763568188df05.

The scheduler changes can result in smaller queries being starved
by bigger queries due to the introduction of global per-node queues.
Reverting for now so we can release. We'll revisit later.