[lldb-dap][test] Avoid a hang on a test failure

[igorkudrin]

Tests in TestDAP_server.py create DebugAdapterServer, passing a connection string. DebugAdapterServer.__init__() creates a socket and passes the associated input and output streams to its parent class, DebugCommunication. DAPTestCaseBase.launch(), which is called from TestDAP_server.run_debug_session(), adds a teardown hook that eventually calls DebugCommunication.terminate(). If the socket is not closed when this hook executes, it waits indefinitely for the receiving thread to join.

In the normal case, when a test passes, the connection is closed by calling self.dap_server.request_disconnect() at the end of TestDAP_server.run_debug_session(). If a test fails, the cleanup hook is called while the connection is still active, which results in a hang. This can be reproduced by removing the call to request_disconnect() or by changing the condition in the assertEqual() on the previous line.

The fix passes the opened socket to 'DebugCommunication' and closes the socket explicitly in 'DebugCommunication.terminate()'.

[llvmorg-github-actions]

@llvm/pr-subscribers-lldb

Author: Igor Kudrin (igorkudrin)

Changes

Tests in TestDAP_server.py create DebugAdapterServer, passing a connection string. DebugAdapterServer.__init__() creates a socket and passes the associated input and output streams to its parent class, DebugCommunication. DAPTestCaseBase.launch(), which is called from TestDAP_server.run_debug_session(), adds a teardown hook that eventually calls DebugCommunication.terminate(). If the socket is not closed when this hook executes, it waits indefinitely for the receiving thread to join.

In the normal case, when a test passes, the connection is closed by calling self.dap_server.request_disconnect() at the end of TestDAP_server.run_debug_session(). If a test fails, the cleanup hook is called while the connection is still active, which results in a hang. This can be reproduced by removing the call to request_disconnect() or by changing the condition in the assertEqual() on the previous line.

The fix passes the opened socket to 'DebugCommunication' and closes the socket explicitly in 'DebugCommunication.terminate()'.

---

Full diff: https://github.com/llvm/llvm-project/pull/209988.diff

1 Files Affected:

• (modified) lldb/packages/Python/lldbsuite/test/tools/lldb-dap/dap_server.py (+5)

diff --git a/lldb/packages/Python/lldbsuite/test/tools/lldb-dap/dap_server.py b/lldb/packages/Python/lldbsuite/test/tools/lldb-dap/dap_server.py
index c8acf67b23b99..8f710154c5da3 100644
--- a/lldb/packages/Python/lldbsuite/test/tools/lldb-dap/dap_server.py
+++ b/lldb/packages/Python/lldbsuite/test/tools/lldb-dap/dap_server.py
@@ -205,11 +205,13 @@ def __init__(
         send: BinaryIO,
         init_commands: Optional[List[str]] = None,
         spawn_helper: Optional[SpawnHelperCallback] = None,
+        socket: Optional[socket.socket] = None,
     ):
         self._log = Log()
         self.send = send
         self.recv = recv
         self.spawn_helper = spawn_helper
+        self.socket = socket
 
         # Packets that have been received and processed but have not yet been
         # requested by a test case.
@@ -1643,6 +1645,8 @@ def request_custom(self, command: str, arguments: Optional[dict[str, Any]] = Non
         return self._send_recv(command_dict)
 
     def terminate(self):
+        if self.socket:
+            self.socket.shutdown(socket.SHUT_RDWR)
         self.send.close()
         if self._recv_thread.is_alive():
             self._recv_thread.join()
@@ -1706,6 +1710,7 @@ def __init__(
                 s.makefile("wb"),
                 init_commands,
                 spawn_helper,
+                socket=s,
             )
             self.connection = connection
         else:

[github-actions]

🐧 Linux x64 Test Results

• 34085 tests passed
• 506 tests skipped

✅ The build succeeded and all tests passed.