minor tweaks: unshard test_tools, shard on -j 2

Lib/test/libregrtest/main.py

@@ -73,7 +73,7 @@ def __init__(self):
         self.tests_to_shard.add('test_concurrent_futures')
         self.tests_to_shard.add('test_multiprocessing_spawn')
         self.tests_to_shard.add('test_asyncio')
-        self.tests_to_shard.add('test_tools')
+        # Only 1 long test case #self.tests_to_shard.add('test_tools')
         self.tests_to_shard.add('test_multiprocessing_forkserver')
         self.tests_to_shard.add('test_multiprocessing_fork')
         self.tests_to_shard.add('test_signal')

Lib/test/libregrtest/runtest_mp.py

@@ -235,7 +235,7 @@ def _run_process(self, test_name: str, tmp_dir: str, stdout_fh: TextIO,
         self.start_time = time.monotonic()
 
         if shard:
-            self.current_test_name = f'{test_name}-shard-{shard.number:02}/{shard.total_shards-1:02}'
+            self.current_test_name = f'{test_name}-subset:{shard.number}/{shard.total_shards}'
         else:
             self.current_test_name = test_name
         try:
@@ -437,10 +437,10 @@ def __init__(self, regrtest: Regrtest) -> None:
         self.output: queue.Queue[QueueOutput] = queue.Queue()
         tests_and_shards = []
         for test in self.regrtest.tests:
-            if self.num_procs > 2 and test in self.regrtest.tests_to_shard:
+            if self.num_procs > 1 and test in self.regrtest.tests_to_shard:
                 # Split shardable tests across multiple processes to run
                 # distinct subsets of tests within a given test module.
-                shards = min(self.num_procs//2+1, 8)  # avoid diminishing returns
+                shards = min(self.num_procs*2//3+1, 10)  # diminishing returns
                 for shard_no in range(shards):
                     tests_and_shards.append((test, ShardInfo(shard_no, shards)))
             else: