Remove bug.py. This is something I sent to Guido via email in or before
'94, demonstrating a thread bug that was later repaired via Python growing
an internal import lock. It's of no current interest, and the now-std
test_threaded_import.py is pretty much the same test.
diff --git a/Demo/threads/README b/Demo/threads/README
index fe27818..fee6aad 100644
--- a/Demo/threads/README
+++ b/Demo/threads/README
@@ -3,7 +3,6 @@
These are mostly "proof of concept" type applications:
Generator.py Generator class implemented with threads.
-bug.py Demonstrate a bug with importing modules in threads.
find.py Parallelized "find(1)" (looks for directories).
sync.py Condition variables primitives by Tim Peters.
telnet.py Version of ../sockets/telnet.py using threads.
diff --git a/Demo/threads/bug.py b/Demo/threads/bug.py
deleted file mode 100644
index 6c5edac..0000000
--- a/Demo/threads/bug.py
+++ /dev/null
@@ -1,69 +0,0 @@
-# The following self-contained little program usually freezes with most
-# threads reporting
-#
-# Unhandled exception in thread:
-# Traceback (innermost last):
-# File "importbug.py", line 6
-# x = whrandom.randint(1,3)
-# AttributeError: randint
-#
-# Here's the program; it doesn't use anything from the attached module:
-
-import thread
-
-def task():
- global N
- import whrandom
- x = whrandom.randint(1,3)
- a.acquire()
- N = N - 1
- if N == 0: done.release()
- a.release()
-
-a = thread.allocate_lock()
-done = thread.allocate_lock()
-N = 10
-
-done.acquire()
-for i in range(N):
- thread.start_new_thread(task, ())
-done.acquire()
-print 'done'
-
-
-# Sticking an acquire/release pair around the 'import' statement makes the
-# problem go away.
-#
-# I believe that what happens is:
-#
-# 1) The first thread to hit the import atomically reaches, and executes
-# most of, get_module. In particular, it finds Lib/whrandom.pyc,
-# installs its name in sys.modules, and executes
-#
-# v = eval_code(co, d, d, d, (object *)NULL);
-#
-# to initialize the module.
-#
-# 2) eval_code "ticker"-slices the 1st thread out, and gives another thread
-# a chance. When this 2nd thread hits the same 'import', import_module
-# finds 'whrandom' in sys.modules, so just proceeds.
-#
-# 3) But the 1st thread is still "in the middle" of executing whrandom.pyc.
-# So the 2nd thread has a good chance of trying to look up 'randint'
-# before the 1st thread has placed it in whrandom's dict.
-#
-# 4) The more threads there are, the more likely that at least one of them
-# will do this before the 1st thread finishes the import work.
-#
-# If that's right, a perhaps not-too-bad workaround would be to introduce a
-# static "you can't interrupt this thread" flag in ceval.c, check it before
-# giving up interpreter_lock, and have IMPORT_NAME set it & restore (plain
-# clearing would not work) it around its call to import_module. To its
-# credit, there's something wonderfully perverse about fixing a race via an
-# unprotected static <grin>.
-#
-# as-with-most-other-things-(pseudo-)parallel-programming's-more-fun-
-# in-python-too!-ly y'rs - tim
-#
-# Tim Peters tim@ksr.com
-# not speaking for Kendall Square Research Corp