fix: Deadlock under load

Author: timfish

module.cc

@@ -369,8 +369,8 @@ void CaptureStackTraces(const FunctionCallbackInfo<Value> &args) {
 
   std::vector<ThreadResult> results;
 
+  std::vector<std::future<ThreadResult>> futures;
   {
-    std::vector<std::future<ThreadResult>> futures;
     std::lock_guard<std::mutex> lock(threads_mutex);
     for (auto &thread : threads) {
       auto thread_isolate = thread.first;
@@ -393,10 +393,13 @@ void CaptureStackTraces(const FunctionCallbackInfo<Value> &args) {
           },
           std::cref(thread_info.async_store)));
     }
+  }
 
-    for (auto &fut : futures) {
-      results.emplace_back(fut.get());
-    }
+  // Wait for all futures to complete AFTER releasing the lock
+  // to avoid deadlock with ThreadPoll trying to acquire the same mutex
+  // https://github.com/getsentry/sentry-javascript-node-native-stacktrace/issues/35
+  for (auto &fut : futures) {
+    results.emplace_back(fut.get());
   }
 
   auto current_context = capture_from_isolate->GetCurrentContext();