fix: add extensive logging and fix subprocess PIPE blocking

1. CI Logging Enhancements:
   - Added comprehensive diagnostics with process tree, network listeners, file descriptors
   - Added timestamps at every stage (before/during/after pytest)
   - Added trap EXIT to always show diagnostics
   - Added immediate process checks after pytest finishes
   - Added sub-shell execution with immediate cleanup

2. Fixed Subprocess PIPE Blocking:
   - Changed Colab mode from PIPE to DEVNULL to prevent blocking
   - PIPE without reading can cause parent process to wait indefinitely

3. Pytest Session Hooks:
   - Added pytest_sessionstart to log initial state
   - Added pytest_sessionfinish for aggressive cleanup before exit
   - Shows all child processes and their status

This should reveal exactly where the hang is happening.

.github/workflows/build-reusable.yml

@@ -263,42 +263,113 @@ jobs:
           # Activate virtual environment
           source .venv/bin/activate || source .venv/Scripts/activate
 
-          # Define diagnostic function for debugging hangs
+          # Define comprehensive diagnostic function
           diag() {
-            echo "===== DIAG BEGIN ====="
+            echo "===== COMPREHENSIVE DIAGNOSTICS BEGIN ====="
             date
-            echo "# pstree (current shell group)"
+            echo ""
-            pstree -ap $$ 2>/dev/null || true
+            echo "### Current Shell Info ###"
-            echo "# python/pytest processes"
+            echo "Shell PID: $$"
-            ps -ef | grep -E 'python|pytest|embedding|zmq|diskann' | grep -v grep || true
+            echo "Shell PPID: $PPID"
-            echo "# network listeners"
+            echo "Current directory: $(pwd)"
+            echo ""
+
+            echo "### Process Tree (full) ###"
+            pstree -ap 2>/dev/null || ps auxf || true
+            echo ""
+
+            echo "### All Python/Pytest Processes ###"
+            ps -ef | grep -E 'python|pytest' | grep -v grep || true
+            echo ""
+
+            echo "### Embedding Server Processes ###"
+            ps -ef | grep -E 'embedding|zmq|diskann' | grep -v grep || true
+            echo ""
+
+            echo "### Network Listeners ###"
             ss -ltnp 2>/dev/null || netstat -ltn 2>/dev/null || true
-            echo "# pytest PIDs"
+            echo ""
-            pgrep -fa pytest || true
+
-            echo "===== DIAG END ====="
+            echo "### Open File Descriptors (lsof) ###"
+            lsof -p $$ 2>/dev/null | head -20 || true
+            echo ""
+
+            echo "### Zombie Processes ###"
+            ps aux | grep '<defunct>' || echo "No zombie processes"
+            echo ""
+
+            echo "### Current Jobs ###"
+            jobs -l || true
+            echo ""
+
+            echo "### /proc/PID/fd for current shell ###"
+            ls -la /proc/$$/fd 2>/dev/null || true
+            echo ""
+
+            echo "===== COMPREHENSIVE DIAGNOSTICS END ====="
           }
 
-          # Run all tests with timeout on Linux to prevent hanging
+          # Run all tests with extensive logging
           if [[ "$RUNNER_OS" == "Linux" ]]; then
-            echo "Running tests with timeout (Linux)..."
+            echo "🚀 Starting Linux test execution with timeout..."
-            # Set trap for diagnostics
+            echo "Current time: $(date)"
-            trap diag INT TERM
+            echo "Shell PID: $$"
 
-            timeout --signal=INT 180 pytest tests/ -vv --maxfail=3 || {
+            # Set trap for diagnostics
-              EXIT_CODE=$?
+            trap diag INT TERM EXIT
-              if [ $EXIT_CODE -eq 124 ]; then
+
-                echo "⚠️ Tests timed out after 180 seconds - dumping diagnostics..."
+            echo "📋 Pre-test diagnostics:"
-                diag
+            ps -ef | grep -E 'python|pytest' | grep -v grep || echo "No python/pytest processes before test"
-                # Try to clean up any leftover processes
+
-                pkill -TERM -P $$ || true
+            echo "🏃 Running pytest with 180s timeout..."
-                sleep 1
+            timeout --preserve-status --signal=INT --kill-after=10 180 bash -c '
-                pkill -KILL -P $$ || true
+              echo "⏱️ Pytest starting at: $(date)"
-              fi
+              pytest tests/ -vv --maxfail=3
-              exit $EXIT_CODE
+              PYTEST_EXIT=$?
-            }
+              echo "✅ Pytest finished at: $(date) with exit code: $PYTEST_EXIT"
+
+              # Immediately check for leftover processes
+              echo "🔍 Post-pytest process check:"
+              ps -ef | grep -E "python|pytest|embedding" | grep -v grep || echo "No leftover processes"
+
+              # Clean up any children before exit
+              echo "🧹 Cleaning up child processes..."
+              pkill -TERM -P $$ 2>/dev/null || true
+              sleep 0.5
+              pkill -KILL -P $$ 2>/dev/null || true
+
+              echo "📊 Final check before exit:"
+              ps -ef | grep -E "python|pytest|embedding" | grep -v grep || echo "All clean"
+
+              exit $PYTEST_EXIT
+            '
+
+            EXIT_CODE=$?
+            echo "🔚 Timeout command exited with code: $EXIT_CODE"
+
+            if [ $EXIT_CODE -eq 124 ]; then
+              echo "⚠️ TIMEOUT TRIGGERED - Tests took more than 180 seconds!"
+              echo "📸 Capturing full diagnostics..."
+              diag
+
+              # More aggressive cleanup
+              echo "💀 Killing all Python processes owned by runner..."
+              pkill -9 -u runner python || true
+              pkill -9 -u runner pytest || true
+            elif [ $EXIT_CODE -ne 0 ]; then
+              echo "❌ Tests failed with exit code: $EXIT_CODE"
+            else
+              echo "✅ All tests passed!"
+            fi
+
+            # Always show final state
+            echo "📍 Final state check:"
+            ps -ef | grep -E 'python|pytest|embedding' | grep -v grep || echo "No Python processes remaining"
+
+            exit $EXIT_CODE
           else
             # For macOS/Windows, run without GNU timeout
-            echo "Running tests ($RUNNER_OS)..."
+            echo "🚀 Running tests on $RUNNER_OS..."
             pytest tests/ -vv --maxfail=3
           fi
 

packages/leann-core/src/leann/embedding_server_manager.py

@@ -402,11 +402,12 @@ class EmbeddingServerManager:
         """Launch the server process with Colab-specific settings."""
         logger.info(f"Colab Command: {' '.join(command)}")
 
-        # In Colab, we need to be more careful about process management
+        # In Colab, redirect to DEVNULL to avoid pipe blocking
+        # PIPE without reading can cause hangs
         self.server_process = subprocess.Popen(
             command,
-            stdout=subprocess.PIPE,
+            stdout=subprocess.DEVNULL,
-            stderr=subprocess.PIPE,
+            stderr=subprocess.DEVNULL,
             text=True,
         )
         self.server_port = port

tests/conftest.py

@@ -184,3 +184,69 @@ def pytest_configure(config):
     # Set default timeout method to thread if not specified
     if not config.getoption("--timeout-method", None):
         config.option.timeout_method = "thread"
+
+    # Add more logging
+    print(f"🔧 Pytest configured at {time.strftime('%Y-%m-%d %H:%M:%S')}")
+    print(f"   Python version: {os.sys.version}")
+    print(f"   Platform: {os.sys.platform}")
+
+
+def pytest_sessionstart(session):
+    """Called after the Session object has been created."""
+    print(f"🏁 Pytest session starting at {time.strftime('%Y-%m-%d %H:%M:%S')}")
+    print(f"   Session ID: {id(session)}")
+
+    # Show initial process state
+    try:
+        import psutil
+
+        current = psutil.Process()
+        print(f"   Current PID: {current.pid}")
+        print(f"   Parent PID: {current.ppid()}")
+        children = current.children(recursive=True)
+        if children:
+            print(f"   ⚠️ Already have {len(children)} child processes at start!")
+    except Exception:
+        pass
+
+
+def pytest_sessionfinish(session, exitstatus):
+    """Called after whole test run finished."""
+    print(f"🏁 Pytest session finishing at {time.strftime('%Y-%m-%d %H:%M:%S')}")
+    print(f"   Exit status: {exitstatus}")
+
+    # Aggressive cleanup before pytest exits
+    print("🧹 Starting aggressive cleanup...")
+
+    try:
+        import psutil
+
+        current = psutil.Process()
+        children = current.children(recursive=True)
+
+        if children:
+            print(f"   Found {len(children)} child processes to clean up:")
+            for child in children:
+                try:
+                    print(f"     - PID {child.pid}: {child.name()} (status: {child.status()})")
+                    child.terminate()
+                except Exception as e:
+                    print(f"     - Failed to terminate {child.pid}: {e}")
+
+            # Wait briefly then kill
+            time.sleep(0.5)
+            _, alive = psutil.wait_procs(children, timeout=1)
+
+            for child in alive:
+                try:
+                    print(f"     - Force killing {child.pid}")
+                    child.kill()
+                except Exception:
+                    pass
+        else:
+            print("   No child processes found")
+
+    except Exception as e:
+        print(f"   Cleanup error: {e}")
+
+    print(f"✅ Pytest exiting at {time.strftime('%Y-%m-%d %H:%M:%S')}")