test: add functional test for deadlock situation

test/functional/p2p_net_deadlock.py

@@ -0,0 +1,37 @@
+#!/usr/bin/env python3
+# Copyright (c) 2023-present The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+import threading
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.util import random_bytes
+
+
+class NetDeadlockTest(BitcoinTestFramework):
+    def set_test_params(self):
+        self.setup_clean_chain = True
+        self.num_nodes = 2
+
+    def run_test(self):
+        node0 = self.nodes[0]
+        node1 = self.nodes[1]
+
+        self.log.info("Simultaneously send a large message on both sides")
+        rand_msg = random_bytes(4000000).hex()
+
+        thread0 = threading.Thread(target=node0.sendmsgtopeer, args=(0, "unknown", rand_msg))
+        thread1 = threading.Thread(target=node1.sendmsgtopeer, args=(0, "unknown", rand_msg))
+
+        thread0.start()
+        thread1.start()
+        thread0.join()
+        thread1.join()
+
+        self.log.info("Check whether a deadlock happened")
+        self.generate(node0, 1)
+        self.sync_blocks()
+
+
+if __name__ == '__main__':
+    NetDeadlockTest().main()

test/functional/test_runner.py

@@ -267,6 +267,7 @@ BASE_SCRIPTS = [
     'p2p_leak_tx.py',
     'p2p_eviction.py',
     'p2p_ibd_stalling.py',
+    'p2p_net_deadlock.py',
     'wallet_signmessagewithaddress.py',
     'rpc_signmessagewithprivkey.py',
     'rpc_generate.py',