[Lldb-commits] [lldb] [lldb] Create dependent modules in parallel (PR #114507)

[Jonas Devlieghere via lldb-commits]

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@@ -1608,9 +1612,48 @@ void Target::SetExecutableModule(ModuleSP &executable_sp,
         if (image_module_sp) {
           added_modules.AppendIfNeeded(image_module_sp, false);
           ObjectFile *objfile = image_module_sp->GetObjectFile();
-          if (objfile)
-            objfile->GetDependentModules(dependent_files);
+          if (objfile) {
+            // Create a local copy of the dependent file list so we don't have
+            // to lock for the whole duration of GetDependentModules.
+            FileSpecList dependent_files_copy;
+            {
+              std::lock_guard<std::mutex> guard(dependent_files_mutex);
+              dependent_files_copy = dependent_files;
+            }
+
+            // Remember the size of the local copy so we can append only the
+            // modules that have been added by GetDependentModules.
+            const size_t previous_dependent_files =
+                dependent_files_copy.GetSize();
+
+            objfile->GetDependentModules(dependent_files_copy);
+
+            {
+              std::lock_guard<std::mutex> guard(dependent_files_mutex);
+              for (size_t i = previous_dependent_files;
+                   i < dependent_files_copy.GetSize(); ++i)
+                dependent_files.AppendIfUnique(
+                    dependent_files_copy.GetFileSpecAtIndex(i));
+            }
+          }
+        }
+      };
+
+      executable_objfile->GetDependentModules(dependent_files);
+
+      llvm::ThreadPoolTaskGroup task_group(Debugger::GetThreadPool());
+      for (uint32_t i = 0; i < dependent_files.GetSize(); i++) {
+        // Process all currently known dependencies in parallel in the innermost
+        // loop. This may create newly discovered dependencies to be appended to
+        // dependent_files. We'll deal with these files during the next
+        // iteration of the outermost loop.
+        {
+          std::lock_guard<std::mutex> guard(dependent_files_mutex);
+          for (; i < dependent_files.GetSize(); i++)
+            task_group.async(GetDependentModules,
----------------
JDevlieghere wrote:

It doesn't, but if that becomes a problem we can do the same trick that Jason suggested and iterate over a copy of the list here. For now that seems unnecessary but hopefully someone will see this comment if that ever changes :-) 

https://github.com/llvm/llvm-project/pull/114507