fix: regtest failures (#5013)

1. Fix a crash bug in RESETSTAT when number of shards is less than number of threads.
2. Tune regtests parameters for pipelining tests to pass.

Signed-off-by: Roman Gershman <roman@dragonflydb.io>

Author: romange

.github/workflows/regression-tests.yml

@@ -55,9 +55,6 @@ jobs:
           aws-access-key-id: ${{ secrets.AWS_S3_ACCESS_KEY }}
           aws-secret-access-key: ${{ secrets.AWS_S3_ACCESS_SECRET }}
           s3-bucket: ${{ secrets.S3_REGTEST_BUCKET }}
-          # Chain ternary oprator of the form (which can be nested)
-          # (expression == condition && <true expression> || <false expression>)
-          epoll: ${{ matrix.proactor == 'Epoll' && 'epoll' || 'iouring' }}
 
       - name: Upload logs on failure
         if: failure()

src/server/server_family.cc

@@ -2224,7 +2224,10 @@ void ServerFamily::ResetStat(Namespace* ns) {
   shard_set->pool()->AwaitBrief(
       [registry = service_.mutable_registry(), ns](unsigned index, auto*) {
         registry->ResetCallStats(index);
-        ns->GetCurrentDbSlice().ResetEvents();
+        EngineShard* shard = EngineShard::tlocal();
+        if (shard) {
+          ns->GetDbSlice(shard->shard_id()).ResetEvents();
+        }
         facade::ResetStats();
         ServerState::tlocal()->exec_freq_count.clear();
       });

tests/dragonfly/connection_test.py

@@ -525,7 +525,7 @@ async def test_keyspace_events_config_set(async_client: aioredis.Redis):
             await collect_expiring_events(pclient, keys)
 
 
-@pytest.mark.exclude_epoll
+@dfly_args({"max_busy_read_usec": 10000})
 async def test_reply_count(async_client: aioredis.Redis):
     """Make sure reply aggregations reduce reply counts for common cases"""
 
@@ -537,6 +537,7 @@ async def measure(aw):
         await aw
         return await get_reply_count() - before - 1
 
+    await async_client.config_resetstat()
     base = await get_reply_count()
     info_diff = await get_reply_count() - base
     assert info_diff == 1
@@ -1121,12 +1122,13 @@ async def wait_for_stuck_on_send():
 
 
 # Test that the cache pipeline does not grow or shrink under constant pipeline load.
-@dfly_args({"proactor_threads": 1, "pipeline_squash": 9, "max_busy_read_usec": 1000})
+@dfly_args({"proactor_threads": 1, "pipeline_squash": 9, "max_busy_read_usec": 10000})
 async def test_pipeline_cache_only_async_squashed_dispatches(df_factory):
     server = df_factory.create()
     server.start()
 
     client = server.client()
+    await client.ping()  # Make sure the connection and the protocol were established
 
     async def push_pipeline(size):
         p = client.pipeline(transaction=True)