IMPALA-13727: Fix wrong regex for hostname in test_multiple_blocks_mt…

…_dop

The test uses r'host=(\S+:[0-9]*)' to match the hosts of all the
fragment instances in query profile, i.e.
  host_list = re.findall(r'host=(\S+:[0-9]*)', result.runtime_profile)
This is able to find the instance name in lines like
  Instance d843c27e276bfa7a:a86450f600000006 (host=name:27002):
and get "name:27002" from it.

However, the runtime profile we get right after fetching the query
result and before closing the query might have a section of total time
after the fragment instance host, e.g.
  Instance d843c27e276bfa7a:a86450f600000006 (host=name:27002):(Total: 19.999ms, non-child: 0.000ns, % non-child: 0.00%)

The regex pattern will match "name:27002):Total:" in the string. If not
all the instances have this "Total" section, the instance names mismatch
and the test will fail. See the query profile attached in the JIRA as an
example. Not sure how this happens. Maybe it's not guaranteed that the
profile is ready immediately when the last result row is fetched. There
might be a delay for the coordinator to process the final update of the
profile from executors. I think it's ok to fix the test first.

This fixes the regex pattern to be r'\(host=([^:]+:[0-9]*)\)' so it can
exactly match the instance name.

Tests
 - Verified the fix locally

Change-Id: If70daa344403f2ae8617bf86e7896c2bbfd9e736
Reviewed-on: http://gerrit.cloudera.org:8080/22457
Reviewed-by: Impala Public Jenkins <[email protected]>
Tested-by: Impala Public Jenkins <[email protected]>

tests/query_test/test_scanners.py

@@ -877,19 +877,20 @@ def test_multiple_blocks_mt_dop(self, vector):
       num_rows_read_list = re.findall(r'RowsRead: [0-9.K]* \(([0-9]*)\)',
         result.runtime_profile)
       # The extra fragment is the "Averaged Fragment"
-      assert len(num_rows_read_list) == 7
-      assert len(ranges_complete_list) == 7
+      assert len(num_rows_read_list) == 7, result.runtime_profile
+      assert len(ranges_complete_list) == 7, result.runtime_profile
 
       # Extract the host for each fragment instance. The first is the coordinator
       # fragment instance.
-      host_list = re.findall(r'host=(\S+:[0-9]*)', result.runtime_profile)
-      assert len(host_list) == 7
+      host_list = re.findall(r'\(host=([^:]+:[0-9]*)\)', result.runtime_profile)
+      assert len(host_list) == 7, result.runtime_profile
+      assert len(set(host_list)) == 3, result.runtime_profile
 
       total_rows_read = 0
       # Skip the Averaged Fragment; it comes first in the runtime profile.
       for num_row_read in num_rows_read_list[1:]:
         total_rows_read += int(num_row_read)
-      assert total_rows_read == TOTAL_ROWS
+      assert total_rows_read == TOTAL_ROWS, result.runtime_profile
 
       # Again skip the Averaged Fragment; it comes first in the runtime profile.
       # With mt_dop 2, every backend will have 2 instances.
@@ -900,7 +901,8 @@ def test_multiple_blocks_mt_dop(self, vector):
           ranges_per_host[host] = 0
         ranges_per_host[host] += int(ranges_complete_list[i])
       for host in ranges_per_host:
-        assert ranges_per_host[host] == 2
+        assert ranges_per_host[host] == 2, ("ScanRangesComplete for " + host
+             + " should be 2 in profile:\n" + result.runtime_profile)
     finally:
       self.client.clear_configuration()