save dmesg -T on the tear_down of blockstore loadtest

cloud/blockstore/tests/python/lib/loadtest_env.py

@@ -15,6 +15,7 @@
 
 import logging
 import os
+import subprocess
 
 
 logger = logging.getLogger(__name__)
@@ -136,6 +137,19 @@ def tear_down(self):
             d.handle.close()
             os.unlink(d.path)
 
+        # It may be beneficial to save dmesg output for debugging purposes.
+        try:
+            dmesg_output = open("dmesg.txt", "w")
+            subprocess.run(
+                ["sudo", "dmesg", "-T"],
+                stdout=dmesg_output,
+                stderr=dmesg_output,
+                timeout=10
+            )
+        except Exception as e:
+            logger.info(f"Failed to save dmesg output: {e}")
+            pass
+
     @property
     def endpoint(self):
         return 'localhost:' + str(self.nbs.nbs_port)