diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 7ac23cab0f..406d1bf2e8 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -210,7 +210,7 @@ jobs:
           path: |
             ./target
           key: |
-            dummy # Cache never be created for this key.
+            s0mth1ng_rand0m # Cache never be created for this key.
           restore-keys: |
             a-cargo-target-${{ matrix.os }}-${{ matrix.profile }}-${{ hashFiles('Cargo.lock') }}-
 
diff --git a/cli/tests/integration_tests_lsp.rs b/cli/tests/integration_tests_lsp.rs
index a6d4f2d297..76041c502d 100644
--- a/cli/tests/integration_tests_lsp.rs
+++ b/cli/tests/integration_tests_lsp.rs
@@ -737,7 +737,7 @@ fn lsp_large_doc_changes() {
     .unwrap();
   client
     .write_notification(
-      "textDocument/didChagne",
+      "textDocument/didChange",
       json!({
         "textDocument": {
           "uri": "file:///a/file.ts",
@@ -1420,6 +1420,152 @@ fn lsp_code_actions_deno_cache() {
   shutdown(&mut client);
 }
 
+#[test]
+fn lsp_code_actions_deadlock() {
+  let mut client = init("initialize_params.json");
+  client
+    .write_notification(
+      "textDocument/didOpen",
+      load_fixture("did_open_params_large.json"),
+    )
+    .unwrap();
+  let (id, method, _) = client.read_request::<Value>().unwrap();
+  assert_eq!(method, "workspace/configuration");
+  client
+    .write_response(id, json!({ "enable": true }))
+    .unwrap();
+  let (maybe_res, maybe_err) = client
+    .write_request::<_, _, Value>(
+      "textDocument/semanticTokens/full",
+      json!({
+        "textDocument": {
+          "uri": "file:///a/file.ts"
+        }
+      }),
+    )
+    .unwrap();
+  assert!(maybe_err.is_none());
+  assert!(maybe_res.is_some());
+  for _ in 0..3 {
+    let (method, _) = client.read_notification::<Value>().unwrap();
+    assert_eq!(method, "textDocument/publishDiagnostics");
+  }
+  client
+    .write_notification(
+      "textDocument/didChange",
+      json!({
+        "textDocument": {
+          "uri": "file:///a/file.ts",
+          "version": 2
+        },
+        "contentChanges": [
+          {
+            "range": {
+              "start": {
+                "line": 444,
+                "character": 11
+              },
+              "end": {
+                "line": 444,
+                "character": 14
+              }
+            },
+            "text": "+++"
+          }
+        ]
+      }),
+    )
+    .unwrap();
+  client
+    .write_notification(
+      "textDocument/didChange",
+      json!({
+        "textDocument": {
+          "uri": "file:///a/file.ts",
+          "version": 2
+        },
+        "contentChanges": [
+          {
+            "range": {
+              "start": {
+                "line": 445,
+                "character": 4
+              },
+              "end": {
+                "line": 445,
+                "character": 4
+              }
+            },
+            "text": "// "
+          }
+        ]
+      }),
+    )
+    .unwrap();
+  client
+    .write_notification(
+      "textDocument/didChange",
+      json!({
+        "textDocument": {
+          "uri": "file:///a/file.ts",
+          "version": 2
+        },
+        "contentChanges": [
+          {
+            "range": {
+              "start": {
+                "line": 477,
+                "character": 4
+              },
+              "end": {
+                "line": 477,
+                "character": 9
+              }
+            },
+            "text": "error"
+          }
+        ]
+      }),
+    )
+    .unwrap();
+  // diagnostics only trigger after changes have elapsed in a separate thread,
+  // so we need to delay the next messages a little bit to attempt to create a
+  // potential for a deadlock with the codeAction
+  std::thread::sleep(std::time::Duration::from_millis(50));
+  let (maybe_res, maybe_err) = client
+    .write_request::<_, _, Value>(
+      "textDocument/hover",
+      json!({
+        "textDocument": {
+          "uri": "file:///a/file.ts",
+        },
+        "position": {
+          "line": 609,
+          "character": 33,
+        }
+      }),
+    )
+    .unwrap();
+  assert!(maybe_err.is_none());
+  assert!(maybe_res.is_some());
+  let (maybe_res, maybe_err) = client
+    .write_request::<_, _, Value>(
+      "textDocument/codeAction",
+      load_fixture("code_action_params_deadlock.json"),
+    )
+    .unwrap();
+  assert!(maybe_err.is_none());
+  assert!(maybe_res.is_some());
+
+  for _ in 0..3 {
+    let (method, _) = client.read_notification::<Value>().unwrap();
+    assert_eq!(method, "textDocument/publishDiagnostics");
+  }
+
+  assert!(client.queue_is_empty());
+  shutdown(&mut client);
+}
+
 #[test]
 fn lsp_completions() {
   let mut client = init("initialize_params.json");
diff --git a/cli/tests/lsp/code_action_params_deadlock.json b/cli/tests/lsp/code_action_params_deadlock.json
new file mode 100644
index 0000000000..be0e317e1d
--- /dev/null
+++ b/cli/tests/lsp/code_action_params_deadlock.json
@@ -0,0 +1,38 @@
+{
+  "textDocument": {
+    "uri": "file:///a/file.ts"
+  },
+  "range": {
+    "start": {
+      "line": 441,
+      "character": 33
+    },
+    "end": {
+      "line": 441,
+      "character": 42
+    }
+  },
+  "context": {
+    "diagnostics": [
+      {
+        "range": {
+          "start": {
+            "line": 441,
+            "character": 33
+          },
+          "end": {
+            "line": 441,
+            "character": 42
+          }
+        },
+        "severity": 1,
+        "code": 7031,
+        "source": "deno-ts",
+        "message": "Binding element 'debugFlag' implicitly has an 'any' type."
+      }
+    ],
+    "only": [
+      "quickfix"
+    ]
+  }
+}
diff --git a/test_util/src/lsp.rs b/test_util/src/lsp.rs
index 52099ebe3f..7b9fc59650 100644
--- a/test_util/src/lsp.rs
+++ b/test_util/src/lsp.rs
@@ -2,6 +2,7 @@
 
 use super::new_deno_dir;
 
+use anyhow::Result;
 use lazy_static::lazy_static;
 use regex::Regex;
 use serde::de;
@@ -9,6 +10,7 @@ use serde::Deserialize;
 use serde::Serialize;
 use serde_json::json;
 use serde_json::Value;
+use std::collections::VecDeque;
 use std::io;
 use std::io::Write;
 use std::path::Path;
@@ -61,7 +63,7 @@ impl<'a> From<&'a [u8]> for LspMessage {
   }
 }
 
-fn read_message<R>(reader: &mut R) -> Result<Vec<u8>, anyhow::Error>
+fn read_message<R>(reader: &mut R) -> Result<Vec<u8>>
 where
   R: io::Read + io::BufRead,
 {
@@ -86,8 +88,12 @@ where
 }
 
 pub struct LspClient {
-  reader: io::BufReader<ChildStdout>,
   child: Child,
+  reader: io::BufReader<ChildStdout>,
+  /// Used to hold pending messages that have come out of the expected sequence
+  /// by the harness user which will be sent first when trying to consume a
+  /// message before attempting to read a new message.
+  msg_queue: VecDeque<LspMessage>,
   request_id: u64,
   start: Instant,
   writer: io::BufWriter<ChildStdin>,
@@ -106,8 +112,51 @@ impl Drop for LspClient {
   }
 }
 
+fn notification_result<R>(
+  method: String,
+  maybe_params: Option<Value>,
+) -> Result<(String, Option<R>)>
+where
+  R: de::DeserializeOwned,
+{
+  let maybe_params = match maybe_params {
+    Some(params) => Some(serde_json::from_value(params)?),
+    None => None,
+  };
+  Ok((method, maybe_params))
+}
+
+fn request_result<R>(
+  id: u64,
+  method: String,
+  maybe_params: Option<Value>,
+) -> Result<(u64, String, Option<R>)>
+where
+  R: de::DeserializeOwned,
+{
+  let maybe_params = match maybe_params {
+    Some(params) => Some(serde_json::from_value(params)?),
+    None => None,
+  };
+  Ok((id, method, maybe_params))
+}
+
+fn response_result<R>(
+  maybe_result: Option<Value>,
+  maybe_error: Option<LspResponseError>,
+) -> Result<(Option<R>, Option<LspResponseError>)>
+where
+  R: de::DeserializeOwned,
+{
+  let maybe_result = match maybe_result {
+    Some(result) => Some(serde_json::from_value(result)?),
+    None => None,
+  };
+  Ok((maybe_result, maybe_error))
+}
+
 impl LspClient {
-  pub fn new(deno_exe: &Path) -> Result<Self, anyhow::Error> {
+  pub fn new(deno_exe: &Path) -> Result<Self> {
     let deno_dir = new_deno_dir();
     let mut child = Command::new(deno_exe)
       .env("DENO_DIR", deno_dir.path())
@@ -125,6 +174,7 @@ impl LspClient {
 
     Ok(Self {
       child,
+      msg_queue: VecDeque::new(),
       reader,
       request_id: 1,
       start: Instant::now(),
@@ -136,49 +186,79 @@ impl LspClient {
     self.start.elapsed()
   }
 
-  fn read(&mut self) -> Result<LspMessage, anyhow::Error> {
+  pub fn queue_is_empty(&self) -> bool {
+    self.msg_queue.is_empty()
+  }
+
+  pub fn queue_len(&self) -> usize {
+    self.msg_queue.len()
+  }
+
+  fn read(&mut self) -> Result<LspMessage> {
     let msg_buf = read_message(&mut self.reader)?;
     let msg = LspMessage::from(msg_buf.as_slice());
     Ok(msg)
   }
 
-  pub fn read_notification<R>(
-    &mut self,
-  ) -> Result<(String, Option<R>), anyhow::Error>
+  pub fn read_notification<R>(&mut self) -> Result<(String, Option<R>)>
   where
     R: de::DeserializeOwned,
   {
-    loop {
-      if let LspMessage::Notification(method, maybe_params) = self.read()? {
-        if let Some(p) = maybe_params {
-          let params = serde_json::from_value(p)?;
-          return Ok((method, Some(params)));
-        } else {
-          return Ok((method, None));
+    if !self.msg_queue.is_empty() {
+      let mut msg_queue = VecDeque::new();
+      loop {
+        match self.msg_queue.pop_front() {
+          Some(LspMessage::Notification(method, maybe_params)) => {
+            return notification_result(method, maybe_params)
+          }
+          Some(msg) => msg_queue.push_back(msg),
+          _ => break,
         }
       }
+      self.msg_queue = msg_queue;
+    }
+
+    loop {
+      match self.read() {
+        Ok(LspMessage::Notification(method, maybe_params)) => {
+          return notification_result(method, maybe_params)
+        }
+        Ok(msg) => self.msg_queue.push_back(msg),
+        Err(err) => return Err(err),
+      }
     }
   }
 
-  pub fn read_request<R>(
-    &mut self,
-  ) -> Result<(u64, String, Option<R>), anyhow::Error>
+  pub fn read_request<R>(&mut self) -> Result<(u64, String, Option<R>)>
   where
     R: de::DeserializeOwned,
   {
-    loop {
-      if let LspMessage::Request(id, method, maybe_params) = self.read()? {
-        if let Some(p) = maybe_params {
-          let params = serde_json::from_value(p)?;
-          return Ok((id, method, Some(params)));
-        } else {
-          return Ok((id, method, None));
+    if !self.msg_queue.is_empty() {
+      let mut msg_queue = VecDeque::new();
+      loop {
+        match self.msg_queue.pop_front() {
+          Some(LspMessage::Request(id, method, maybe_params)) => {
+            return request_result(id, method, maybe_params)
+          }
+          Some(msg) => msg_queue.push_back(msg),
+          _ => break,
         }
       }
+      self.msg_queue = msg_queue;
+    }
+
+    loop {
+      match self.read() {
+        Ok(LspMessage::Request(id, method, maybe_params)) => {
+          return request_result(id, method, maybe_params)
+        }
+        Ok(msg) => self.msg_queue.push_back(msg),
+        Err(err) => return Err(err),
+      }
     }
   }
 
-  fn write(&mut self, value: Value) -> Result<(), anyhow::Error> {
+  fn write(&mut self, value: Value) -> Result<()> {
     let value_str = value.to_string();
     let msg = format!(
       "Content-Length: {}\r\n\r\n{}",
@@ -194,7 +274,7 @@ impl LspClient {
     &mut self,
     method: S,
     params: V,
-  ) -> Result<(Option<R>, Option<LspResponseError>), anyhow::Error>
+  ) -> Result<(Option<R>, Option<LspResponseError>)>
   where
     S: AsRef<str>,
     V: Serialize,
@@ -209,24 +289,19 @@ impl LspClient {
     self.write(value)?;
 
     loop {
-      if let LspMessage::Response(id, result, error) = self.read()? {
-        assert_eq!(id, self.request_id);
-        self.request_id += 1;
-        if let Some(r) = result {
-          let result = serde_json::from_value(r)?;
-          return Ok((Some(result), error));
-        } else {
-          return Ok((None, error));
+      match self.read() {
+        Ok(LspMessage::Response(id, maybe_result, maybe_error)) => {
+          assert_eq!(id, self.request_id);
+          self.request_id += 1;
+          return response_result(maybe_result, maybe_error);
         }
+        Ok(msg) => self.msg_queue.push_back(msg),
+        Err(err) => return Err(err),
       }
     }
   }
 
-  pub fn write_response<V>(
-    &mut self,
-    id: u64,
-    result: V,
-  ) -> Result<(), anyhow::Error>
+  pub fn write_response<V>(&mut self, id: u64, result: V) -> Result<()>
   where
     V: Serialize,
   {
@@ -238,11 +313,7 @@ impl LspClient {
     self.write(value)
   }
 
-  pub fn write_notification<S, V>(
-    &mut self,
-    method: S,
-    params: V,
-  ) -> Result<(), anyhow::Error>
+  pub fn write_notification<S, V>(&mut self, method: S, params: V) -> Result<()>
   where
     S: AsRef<str>,
     V: Serialize,