Fix memory leak during parallel writing with multiplied warnings.

2 files changed, 9 insertions, 3 deletions

diff --git a/sphinx/builders/__init__.py b/sphinx/builders/__init__.py
index 5370dd70..bbb9b311 100644
--- a/sphinx/builders/__init__.py
+++ b/sphinx/builders/__init__.py
@@ -357,9 +357,11 @@ class Builder(object):
 
     def _write_parallel(self, docnames, warnings, nproc):
         def write_process(docs):
+            local_warnings = []
+            self.env.set_warnfunc(lambda *args: local_warnings.append(args))
             for docname, doctree in docs:
                 self.write_doc(docname, doctree)
-            return warnings
+            return local_warnings
 
         def add_warnings(docs, wlist):
             warnings.extend(wlist)
diff --git a/sphinx/util/parallel.py b/sphinx/util/parallel.py
index 5f9e8eff..7e238ab1 100644
--- a/sphinx/util/parallel.py
+++ b/sphinx/util/parallel.py
@@ -101,7 +101,9 @@ class ParallelTasks(object):
             del self._threads[tid]
             if exc:
                 raise SphinxParallelError(*result)
-            self._result_funcs.pop(tid)(arg, result)
+            result_func = self._result_funcs.pop(tid)(arg, result)
+            if result_func:
+                result_func(result)
             self._nprocessed += 1
 
     def join(self):
@@ -110,7 +112,9 @@ class ParallelTasks(object):
             del self._threads[tid]
             if exc:
                 raise SphinxParallelError(*result)
-            self._result_funcs.pop(tid)(arg, result)
+            result_func = self._result_funcs.pop(tid)(arg, result)
+            if result_func:
+                result_func(result)
             self._nprocessed += 1
 
         # there shouldn't be any threads left...