From: Miss Islington (bot) <31488909+miss-islington@users.noreply.github.com>
Date: Fri, 29 May 2020 12:17:42 +0000 (-0700)
Subject: [3.8] bpo-25872: Fix KeyError in linecache when multithreaded (GH-18007) (GH-20092)
X-Git-Tag: v3.7.8rc1~33
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=852e8a7ed4d3d48e5c1c8120cfc932eb6a84bb8e;p=thirdparty%2FPython%2Fcpython.git

[3.8] bpo-25872: Fix KeyError in linecache when multithreaded (GH-18007) (GH-20092)


Backporting to 3.8 and adding a NEWS item (I should have added one to the master branch -- oh well).
(cherry picked from commit b86636bff4b29ce23c886df079715dd951f13a07)

Co-authored-by: Andrew Kuchling <amk@amk.ca>
---

diff --git a/Lib/linecache.py b/Lib/linecache.py
index 3afcce1f0a14..c87e1807bfaf 100644
--- a/Lib/linecache.py
+++ b/Lib/linecache.py
@@ -73,10 +73,10 @@ def checkcache(filename=None):
         try:
             stat = os.stat(fullname)
         except OSError:
-            del cache[filename]
+            cache.pop(filename, None)
             continue
         if size != stat.st_size or mtime != stat.st_mtime:
-            del cache[filename]
+            cache.pop(filename, None)
 
 
 def updatecache(filename, module_globals=None):
@@ -86,7 +86,7 @@ def updatecache(filename, module_globals=None):
 
     if filename in cache:
         if len(cache[filename]) != 1:
-            del cache[filename]
+            cache.pop(filename, None)
     if not filename or (filename.startswith('<') and filename.endswith('>')):
         return []
 
diff --git a/Misc/NEWS.d/next/Library/2020-05-14-13-25-36.bpo-25872.5D5538.rst b/Misc/NEWS.d/next/Library/2020-05-14-13-25-36.bpo-25872.5D5538.rst
new file mode 100644
index 000000000000..3fd8bac73edb
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2020-05-14-13-25-36.bpo-25872.5D5538.rst
@@ -0,0 +1,2 @@
+:mod:`linecache` could crash with a :exc:`KeyError` when accessed from multiple threads.
+Fix by Michael Graczyk.