Merge pull request #289 from qdrant/docs-stacktrace

Document stack trace in troubleshooting

qdrant-landing/content/documentation/guides/common-errors.md

@@ -30,3 +30,59 @@ ulimit -n 10000
 ```
 
 Please note, the command should be executed before you run Qdrant server.
+
+## Qdrant stuck/frozen, extract stack trace
+
+*Available as of v1.5.0*
+
+It might happen that Qdrant is completely stuck. Operations may hang
+indefinitely or an optimization may be stuck forever. Waiting some time does not
+improve the situation.
+
+If you encounter this situation, always check the Qdrant logs first. It may give some
+valuable information on what is happening.
+
+When logs don't show any pointers to the problem, you may extract a stack trace
+from the Qdrant server to report the current state of what it is doing. This can
+be done by visiting [`/stacktrace`](http://localhost:6333/stacktrace) in your
+browser. You can attach this stack trace to an issue report to help Qdrant
+developers debug the issue.
+
+```http
+GET /stacktrace
+
+{
+  "result": {
+    "threads": [
+      {
+        "id": 7,
+        "name": "qdrant",
+        "frames": [
+          "",
+          "",
+          ":0 - qdrant::main::h6b7c98553f8d540b ",
+          ":0 - std::sys_common::backtrace::__rust_begin_short_backtrace::ha4aa73ba5e009f1f "
+        ]
+      },
+      {
+        "id": 8,
+        "name": "search-0",
+        "frames": [
+          ":0 - epoll_wait ",
+          ":0 - mio::poll::Poll::poll::h91178360524c8cd2 "
+        ]
+      },
+      {
+        "id": 9,
+        "name": "search-1",
+        "frames": [
+          ":0 - syscall ",
+          ":0 - parking_lot::condvar::Condvar::wait_until_internal::h26d4f821b8427131 "
+        ]
+      }
+    ]
+  },
+  "status": "ok",
+  "time": 0.03003201
+}
+```