diff --git a/src/calibre/ebooks/oeb/polish/tests/base.py b/src/calibre/ebooks/oeb/polish/tests/base.py
index dd78065d52..fcc21004a4 100644
--- a/src/calibre/ebooks/oeb/polish/tests/base.py
+++ b/src/calibre/ebooks/oeb/polish/tests/base.py
@@ -86,7 +86,8 @@ def get_split_book(fmt='epub'):
     src = os.path.join(os.path.dirname(__file__), 'split.html')
     if needs_recompile(ans, src):
         x = src.replace('split.html', 'index.html')
-        raw = open(src, 'rb').read().decode('utf-8')
+        with open(src, 'rb') as sf:
+            raw = sf.read().decode('utf-8')
         try:
             with open(x, 'wb') as f:
                 f.write(raw.encode('utf-8'))
diff --git a/src/calibre/scraper/simple.py b/src/calibre/scraper/simple.py
index 8dcb423901..fdbf8a5af1 100644
--- a/src/calibre/scraper/simple.py
+++ b/src/calibre/scraper/simple.py
@@ -97,6 +97,8 @@ class Overseer:
             for w in self.workers.values():
                 w.stdin.write(b'EXIT:0\n')
                 w.stdin.flush()
+                w.stdin.close()
+                w.stdout.close()
             for w in self.workers.values():
                 if self.safe_wait(w, 0.2) is None:
                     w.terminate()
diff --git a/src/calibre/utils/lock.py b/src/calibre/utils/lock.py
index c9ee5fb608..ab301018b2 100644
--- a/src/calibre/utils/lock.py
+++ b/src/calibre/utils/lock.py
@@ -87,10 +87,14 @@ def lock_file(path, timeout=15, sleep_time=0.2):
             timeout, sleep_time, windows_open, windows_retry, path
         )
     f = unix_open(path)
-    retry_for_a_time(
-        timeout, sleep_time, fcntl.flock, unix_retry,
-        f.fileno(), fcntl.LOCK_EX | fcntl.LOCK_NB
-    )
+    try:
+        retry_for_a_time(
+            timeout, sleep_time, fcntl.flock, unix_retry,
+            f.fileno(), fcntl.LOCK_EX | fcntl.LOCK_NB
+        )
+    except Exception:
+        f.close()
+        raise
     return f
 
 
diff --git a/src/calibre/utils/test_lock.py b/src/calibre/utils/test_lock.py
index 22968baf2d..411ac63adf 100644
--- a/src/calibre/utils/test_lock.py
+++ b/src/calibre/utils/test_lock.py
@@ -109,6 +109,7 @@ class IPCLockTest(unittest.TestCase):
         finally:
             if child.poll() is None:
                 child.kill()
+                child.wait()
 
     def test_exclusive_file_other_process_clean(self):
         self.run_other_ef_op(True)